Módulo 3 Med. Interna Flashcards
A 60-year-old man comes to his physician with complaints of easy fatigability and palpitations for the past 6 months. Physical examination is remarkable for pallor of skin and mucous membranes. No evidence of cardiac or respiratory disease is found. Hematologic studies show:
- Hemoglobin: 8.4 g/dL
- Mean corpuscular volume (MCV): 75 fl
- Leukocyte count 9000/mm3
- Platelet count 380,000/mm3
Serum chemistry studies show a ferritin of 25 ng/L and serum bilirubin within normal values. Peripheral blood smear shows small erythrocytes with marked variability in size. Which of the following is the most appropriate next step in management?
(A) Bone marrow biopsy
(B) Coombs test for anti-red blood cell antibodies
(C) Hemoglobin electrophoresis
(D) Test for occult blood in the stool
(E) Therapeutic trial with oral ferrous sulfate
(F) Treatment with vitamin B12 and folic acid
Respuesta: B
The correct answer is B. This infant has the classic presentation of pyloric stenosis. It occurs more commonly among first-born males, particularly white males. The cause of pyloric stenosis is unknown. It usually presents with nonbilious vomiting at 3-6 weeks of age. It progresses from intermittent vomiting to increasing numbers of episodes with more and more forceful vomiting. The infant acts hungry afterward, but as the vomiting continues there is loss of fluids and electrolytes resulting in hypochloremic metabolic alkalosis. Abdominal examination usually reveals a pyloric lump that feels like an olive-size mass. Treatment for pyloric stenosis is surgical; therefore, immediate consultation with the surgeon is necessary. The surgeon will preoperatively correct the metabolic alkalosis and surgically perform a pyloromyotomy. Changing the feedings to clear liquids and a solution, such as
Pedialyte (choice A), will not relieve this obstruction and will only delay the needed surgical treatment.
Obtaining abdominal x-ray films (choice C) will not delineate the specific problem. Appropriate x-ray films in this situation include either a barium swallow, which will reveal a large stomach with only thin streaks of barium in the pylorus due to the hypertrophied pylorus, or an ultrasound, which will reveal a doughnut appearance of the pyloric area.
Insertion of a nasogastric tube (choice D) will relieve an overdistended stomach, but will not treat the underlying problem.
Treating the infant with parenteral antibiotics (choice E) is not indicated. This is not an infectious condition, and prophylactic antibiotics are not used in conjunction with the surgery.
A 28-year-old woman presents with painful swelling of her right hand and fingers of 2 days’ duration. She has a low-grade fever and is currently menstruating. She denies a past history of sexually transmitted diseases. On examination, her temperature is 38.6 C
(101.4 F), blood pressure is 130/70 mm Hg, pulse is 110/min, and respirations are 20/min. The digits on her right hand are swollen and held in mild flexion, with papules and vesicles in the web spaces. Her left knee and ankle are swollen and tender to touch. Laboratory evaluation shows:
- Leukocytes 12,000 with 86% neutrophils
- Hemoglobin 14.0 g/dL
- Platelets 220,000/mm3
- Erythrocyte sedimentation rate 43 mm/h
X-ray films of the hand, knee, and ankle show no evidence of fracture. Which of the following tests is most likely to confirm the likely diagnosis?
(A) Cultures of cervix, rectum, throat, and blood
(B) Blood cultures
(C) Arthrocentesis for bacterial cultures
(D) Synovial fluid analysis for cell count
(E) Synovial fluid Gram stain
Respuesta: D
The correct answer is D. The condition is called transient hypogammaglobulinemia of infancy. It is due to exhaustion of maternally supplied IgG (the only antibody to cross the placenta in significant amounts) before the infant has begun to produce significant amounts of his own antibodies. Affected infants typically go through several months to years of being very vulnerable to infection, and then improve as their immune systems mature and they are able to produce more IgG. The condition does not present in the neonatal period because maternal IgG can cross the placenta during the third trimester of intrauterine life. The maternally supplied IgG is usually exhausted by about the 4th to 6th month of life.
IgA (choice A) is found in secretions and in serum but does not cross the placenta.
IgD (choice B) is a transiently produced antibody during B cell development that is present in trace amounts in serum.
IgE (choice C) is the antibody associated with allergic reactions; it does not cross the placenta.
IgM (choice E) is a large antibody found in serum that does not cross the placenta.
A 39-year-old California rancher consults a physician because of
chronic abdominal pain. The man has been a sheepherder for 23 years. Physical examination is notable for a palpable liver mass but is otherwise unremarkable. Ultrasound demonstrates a 15-cm cyst bearing multiple daughter cysts in the liver. CT confirms the presence of the cysts and demonstrates the presence of a finely calcified cyst rim. Which of the following is the most likely diagnosis?
(A) Ascariasis
(B) Echinococcosis
(C) Fascioliasis
(D) Schistosomiasis
(E) Toxocariasis
Respuesta: B
The correct answer is B. This is hydatid disease, due to infection with E. granulosus (rarely Echinococcus multilocularis). The life cycle of this parasitic worm usually alternates between sheep and canine carnivores (including sheep herding dogs). Man is an accidental host. Endemic areas correspond to the major sheepherding areas of the world: the Mediterranean, the Middle East, Australia, New Zealand, South Africa, and South America. Smaller foci of the disease are found in California, Canada, and Alaska. The ingested egg hatches in the intestine, and the larva migrates to the human liver, lungs, or, less commonly, other body sites. Over years, the larva forms the hydatid cyst, which is a large, fluid-filled bladder that develops multiple brood capsules in its periphery, each of which contains numerous small infective scolices. So long as the cyst does not rupture, the patient may be asymptomatic. However, rupture (including accidental surgical rupture) can cause an anaphylactic reaction (the cyst fluid is highly antigenic) or a “metastatic” infection, as the up to millions of infectious scolices are released. Treatment can be either with very careful surgical resection or with percutaneous aspiration under CT guidance followed by instillation of a scolecoidal agent and then reaspiration. If the case is inoperable, or if an intraoperative spillage occurs, albendazole can be used to suppress growth or kill the cysts.
Ascariasis (choice A) can cause biliary obstruction by the adult worms and granulomas in the liver by the larvae.
Fascioliasis (choice C) can acutely cause tender hepatomegaly with fever and eosinophilia, and can chronically cause cholangitis and biliary fibrosis.
Schistosomiasis (choice D) can cause a severe granulomatous reaction to the ova, producing hepatosplenomegaly, pipestem fibrosis, and portal hypertension.
Toxocariasis (choice E) can cause visceral larva migrans and hepatomegaly with granulomas.
A solitary nodule is detected on a chest x-ray film in an otherwise healthy 25-year-old man. The patient has been smoking 10 cigarettes daily for 3 years. The nodule is located in the right middle lobe and measures approximately 1.5 cm. Previous chest x-ray films are not available for comparison. CT scan reveals a solitary lung nodule with a smooth contour and diffuse calcifications. No other pulmonary lesions are found. Physical examination and routine laboratory tests are normal. Which of the following is the most likely diagnosis?
(A) Aspergilloma
(B) Bronchogenic carcinoma
(C) Hamartoma
(D) Pulmonary abscess
(E) Sarcoidosis
(F) Secondary (reactivated) tuberculosis
Respuesta:
The correct answer is C. This case raises the problem of the clinical approach to a solitary pulmonary nodule radiographically detected in an otherwise healthy subject. In large surveys, 60% of solitary pulmonary nodules are benign, and granulomas represent the most common benign lesion. However, there is no infallible clinical or radiologic set of criteria that can discriminate between benign and malignant lesions. Factors favoring a benign lesion include young age (< 40 to 45 years), small size (< 2 cm) and smooth margins of the lesion, absence of symptoms, and slow growth on successive films. Generally, calcification is not a malignant feature, and presence of “popcorn-like” calcifications definitely favors hamartoma. A hamartoma is a malformative lesion resulting from random admixture of tissues normally present in the lung, including cartilage, bronchial mucosa, and smooth muscle. It is usually discovered incidentally.
An aspergilloma (choice A) is a fungus ball (mycetoma) that develops in a pre-existing lung cavity. It may be seen as an asymptomatic radiographic abnormality (a crescent of air outlining a solid mass that moves with position changes) that is usually in the upper lobe. An aspergilloma can cause hemoptysis, and there are often other systemic signs. Hemoptysis is frequently present, and signs and symptoms of the underlying disease should be found.
Bronchogenic carcinoma (choice B) may present as a solitary nodule, but patients are typically older and have a much longer exposure to cigarette smoking. Calcifications usually are not seen in malignant pulmonary tumors.
Pulmonary abscess (choice D) manifests as a pulmonary infiltrate with cavitation and, frequently, an air-fluid level. Accompanying symptomatology, such as fever and cough, is usually present.
Sarcoidosis (choice E) affects the lungs frequently. A diffuse multinodular infiltrate is seen on chest x-ray, most commonly associated with hilar lymphadenopathy. The patient may have signs and symptoms of restrictive pulmonary disease.
Secondary (reactivated) tuberculosis (choice F) manifests with multiple nodular and cavitary infiltrates in the upper lobes; the patient has low-grade fever, malaise, weight loss, and cough. However, primary tuberculosis may result in a calcified nodule within the lung parenchyma, which is the remnant of an old Ghon complex.
A 65-year-old woman is admitted with a 3-week history of headache over the right temporal region, malaise, fever, morning stiffness, and weight loss. On physical examination, scalp tenderness is appreciated. Her temperature is 38.5 C (101.3 F), blood pressure is 142/84 mm Hg, pulse is 85/min, and respirations are 14/min. There is no loss of visual acuity, and funduscopic examination is unremarkable. Laboratory studies show the following:
- Hematocrit: 40.3%
- Hemoglobin: 11.9 g/dL
- Leukocytes: 7800/mL (neutrophils 68%)
- Erythrocyte sedimentation rate (ESR): 80 mm/h
After reviewing the results, the physician initiates highdose prednisone therapy. Which of the following is most likely to confirm the diagnosis?
(A) CT scan of the head
(B) Lumbar puncture
(C) Muscle biopsy
(D) Temporal artery biopsy
(E) Visual evoked potentials
Respuesta: D
The correct answer is D. The patient has signs, symptoms, and laboratory findings consistent with giant cell arteritis, which is a systemic disease overlapping with polymyalgia rheumatica. It affects the superficial temporal artery most commonly but may involve any medium-sized or large caliber artery in the body. The most characteristic elements in the diagnosis include scalp tenderness (sometimes associated with palpation of a nodular and tender temporal artery), elevated ESR, a frequently normal leukocyte count, and age older than 55 years. The major risk of this condition is blindness deriving from extension of the inflammatory process to the ophthalmic artery. Prednisone therapy must be immediately started, and a biopsy of the temporal artery should be obtained to confirm the diagnosis.
CT scan of the head (choice A) would be useful to obtain information in case of suspected intracranial lesions, especially bleeding, infarct, or a space-occupying mass.
Lumbar puncture (choice B) for CSF examination would have no diagnostic value in this patient. Meningitis would develop more rapidly, usually with nuchal headache and rigidity. Subarachnoid hemorrhage results in thunderclap headache followed by changes in mental status.
Muscle biopsy (choice C) is useful in investigating muscular disorders. Myalgia, arthralgia, and stiffness in the pelvic and shoulder girdles are often present in this condition, which may mimic a myopathy.
Visual evoked potentials (choice E) are especially useful in evaluation of optic nerve involvement in demyelinating diseases.
A 35-year-old man goes to the emergency department because he has developed a severe case of hives. He has never had hives before. Physical examination demonstrates multiple wheals and
erythematous patches over his body, which respond to subcutaneous epinephrine. The patient’s sclera are slightly yellow-tinged. Results of the chest and abdomen examination are within normal limits. Screening biochemistry tests demonstrate an AST (SGOT) of 350 U/L and an ALT (SGPT) of 300 U/L. Which of the following is the
most likely diagnosis?
(A) Alcoholic cirrhosis
(B) Alpha1-antitrypsin deficiency
(C) Hemochromatosis
(D) Hepatitis A
(E) Hepatitis B
Respuesta: E
The correct answer is E. Urticaria, or hives, is a common condition that can be quite difficult to manage because it may have such a wide variety of triggers. The underlying basis of the condition is mediator- (histamine, serotonin, leukotrienes) driven vasodilation with accompanying dermal edema. The triggers for mediator release from mast cells or basophils may be either allergic (IgE bound to antigen) or nonimmunologic direct pharmacologic effects. Although there is a wide range of possible triggers for urticaria, it is important to note that up to 25% of cases of acute hepatitis B present with urticaria. It is therefore well worth checking the sclera (the most visible site in tanned or dark-skinned individuals) for jaundice in patients with newly diagnosed hives. Other triggers include contact chemicals, drugs, food allergens, pressure, sunlight, insect stings, and hereditary predispositions.
All the other choices can produce acute or chronic hepatitis but do not have a significant association with urticaria.
A 47-year-old Brazilian immigrant presents with fatigue and dyspnea. He has been healthy for the past 10 years. The patient denies fever, cough, chills, or weight loss. On physical examination there are no murmurs, the pulse and the rhythm are regular, S1 is normal, and S2 is split. This split increases with inspiration and persists with expiration. Which of the following ECG findings is most consistent with the auscultatory findings in this patient?
(A) Acute ST segment elevation in the anterior leads
(B) Decreased PR interval
(C) Early repolarization
(D) Marked T wave inversion
(E) Right bundle branch block
Respuesta: E
The correct answer is E. A persistently wide split S2 is typically seen in patients with right bundle branch block, pulmonic stenosis, pulmonary embolus, and ectopic or pacemaker beats originating in the left ventricle. All these conditions produce delayed function of the right ventricle. In a Brazilian patient, Chagas disease (caused by Trypanosoma cruzi) should be considered as a possible cause of heart block. This trypanosomal infection is endemic in Central and South American countries, and is a cause of rhythm disturbances, cardiomyopathy, and thromboembolism.
ST segment elevation (choice A) is seen in acute anterior myocardial infarction.
A short PR interval (choice B) is associated with a loud S1 (when the mitral valve slams shut).
Early repolarization (choice C) will produce ECG changes only with no specific findings on auscultation.
Although modest T wave changes can sometimes be associated with right bundle branch block, marked T wave inversions (choice D) are more typical of right or left ventricular hypertrophy and myocardial ischemia or infarction.
An otherwise healthy 60-year-old man undergoes a health
maintenance examination. Physical examination and medical history are unremarkable. A blood chemistry panel is normal except for a serum calcium level of 11 mg/dL when corrected for serum albumin. The measurement is repeated two times, giving values of 10.5 mg/dL and 11.2 mg/dL, respectively. Serum phosphorus is 2.5 mg/dL, and alkaline phosphatase is 50 U/L. Immunoradiometric assay (IRMA) reveals higher than normal serum levels of parathyroid hormone. Urine calcium excretion is within normal limits. The patient denies previous renal colic or urinary tract infections. Which of the following is the most appropriate next step in management?
(A) Bone x-ray films
(B) Extensive cancer screening
(C) Generous fluid intake
(D) Treatment with bisphosphonates (e.g., alendronate)
(E) Surgical exploration of the neck
Respuesta: C
The correct answer is C. Hyperparathyroidism is one of the most frequent endocrinologic conditions, found in 1 in 1000 adults. In most cases, hyperparathyroidism is asymptomatic, manifesting only with hypercalcemia often discovered incidentally in the course of routine laboratory investigations conducted for other reasons. The most common cause is a parathyroid adenoma. Calcium levels should be corrected for albuminemia, since most of the calcium is bound to serum albumin. If hypercalcemia is the only clinical sign, without associated complications such as renal stones, bone disease, or cataracts, abundant fluid intake is the only measure recommended to prevent formation of calcium stones in the urinary system.
Bone x-ray films (choice A) are not necessary for the diagnostic work-up of hypercalcemia and hyperparathyroidism, unless bone pain or pathologic fractures are present. X-ray films may reveal bone rarefaction, which is often more pronounced in the phalanges and in subperiosteal locations.
Extensive cancer screening (choice B) would be appropriate if hypercalcemia were suspected to be secondary to neoplasms (e.g., lung, breast, renal cell carcinoma, multiple myeloma). Hypercalcemia of malignancy can be due to secretion of PTH-like substances or bone destruction by metastases. In either case, plasma levels of PTH detected by IRMA would be low. In fact, the PTHlike peptides produced by some tumors (lung cancer) are not identified by IRMA. Alkaline phosphatase would be high in the presence of osteolysis.
Treatment with bisphosphonates (e.g., alendronate; choice D) may serve as an alternative treatment to prevent excessive bone resorption.
Surgical exploration of the neck (choice E) is aimed at finding the source of increased PTH production, which is usually a parathyroid adenoma. Removal of the adenoma is recommended when patients have symptomatic hyperparathyroidism, with recurrent renal stones or bone disease. Indications for surgical treatment in asymptomatic patients include very high calcium levels, high urinary excretion of calcium, extreme bone loss, or difficulty in medical follow-up.
A 27-year-old African American man visits his primary care
physician because of recent onset of “yellowness in the white of his eyes.” His recent history is significant for a “chest cold” for which he is taking trimethoprim-sulfamethoxazole; he is also taking fluoxetine for depression. On examination, the sclera are icteric and the mucosa beneath the tongue appears yellow. No hepatosplenomegaly is present. Laboratory studies are as follows:
- Hemoglobin 11.1 g/dL
- Hematocrit 34%
- Total bilirubin 6.2 mg/dL
- Conjugated (direct) bilirubin 0.8 mg/dL
- Alkaline phosphatase 77
- AST (SGOT) 24
- ALT (SGPT) 22
Which of the following is the most likely explanation for this patient’s jaundice?
(A) Acute infectious hepatitis
(B) Cholestatic liver disease
(C) Drug reaction from fluoxetine
(D) Drug reaction from trimethoprim-sulfame-thoxazole
Respuesta: D
The correct answer is D. This man has glucose-6-phosphate dehydrogenase (G6PD) deficiency (as do 10% of African American males). G6PD serves to protect the RBCs from oxidative damage by maintaining high intracellular levels of NADPH. People of Mediterranean descent can also have G6PD deficiency, but to a much greater degree. Therefore, hemolytic episodes in this population are more severe (and can be fatal), as compared with those in the African American population, which are usually mild and self-limited. Common oxidative stressors that initiate hemolysis are drug reactions (especially sulfa drugs), febrile illnesses, and fava bean ingestion.
Acute infectious hepatitis (choice A) would more likely present with fatigue, fever, abdominal pain, hepatomegaly, and high elevations of AST and ALT (often into the 1000s).
Cholestatic liver disease (choice B) more often presents with elevation of alkaline phosphatase, along with mild elevations of AST and ALT. This patient has elevated unconjugated bilirubin levels, as in hemolytic disorders. Both hepatocellular (hepatitis) and cholestatic liver disease cause more conjugated (as opposed to unconjugated) hyperbilirubinemia.
The most common side effects of fluoxetine (a selective serotonin reuptake inhibitor; choice C) are anxiety, agitation, and insomnia.
A 26-year-old woman complains of painful and frequent urination for 2 days. She has no significant medical history and has had a monogamous sexual relationship with another woman for the past year. Her temperature is 37.2 C (99 F), blood pressure is 120/70 mm Hg, pulse is 68/min, and respirations are 12/min. There is no costovertebral angle tenderness, the abdomen is soft, and there is mild suprapubic tenderness. The pelvic examination is within normal limits except for tenderness at the urethral meatus. Urinalysis reveals 23 white blood cells per high-power field. Which of the following is the most likely pathogen?
(A) Chlamydia trachomatis
(B) Escherichia coli
(C) Klebsiella pneumoniae
(D) Proteus sp.
(E) Staphylococcus saprophyticus
Respuesta: B
The correct answer is B. Escherichia coli, a coliform bacteria, is the most common cause of urinary tract infection (UTI) and is therefore seen much more often than Klebsiella (choice C) and Proteus (choice D). E. coli causes about 80% of UTIs in patients without urologic abnormalities. Coliform bacteria colonize the urethra, and ascending infection may lead to cystitis or pyelonephritis.
Chlamydia trachomatis (choice A) is part of the differential diagnosis for UTI in a sexually active patient with dysuria. However, the patient often has a vaginal discharge. Urine culture usually shows < 100 organisms. On physical examination, the patient with Chlamydia may have cervical motion tenderness if cervicitis is present.
Staphylococcus saprophyticus (choice E) is another common cause of UTIs in young women, often after heterosexual intercourse.
A 72-year-old man complains of malaise and easy fatigability for the past 3 weeks. His past medical history is significant for gout and pneumonia. He lives alone and usually drinks two six-packs of beer daily. His temperature is 36.9 C (98.4 F), blood pressure is 160/90 mm Hg, pulse is 88/min, and respirations are 19/min. Thyroid palpation is normal, and heart, lung, and abdomen examination results are within normal limits. There is a diffuse ecchymotic rash spreading out from hair follicles on the limbs and trunk. The patient most likely has a deficiency of which of the following vitamins?
(A) Niacin
(B) Thiamin
(C) Vitamin B12
(D) Vitamin C
(E) Vitamin D
Respuesta: D
The correct answer is D. This question examines the different aspects of vitamin deficiencies. Scurvy is a deficiency of vitamin C that may occur in older men who cook for themselves. The features are perifollicular hemorrhage and purpura, splinter hemorrhages, and gum involvement. Normochromic, normocytic anemia is common.
Niacin deficiency (choice A), known as pellagra, is a chronic wasting disease associated with dermatitis, dementia, and diarrhea. The skin lesions are characterized by hyperkeratosis, hyperpigmentation, and desquamation. The course is progressive over several years. Niacin is found in cereals.
Vitamin B1 (thiamine) deficiency (choice B), known as beriberi, occurs in alcoholics and food faddists. Two manifestations of deficiency include cardiovascular disease (high output failure) and neurologic disorders (e.g., Wernicke-Korsakoff syndrome, characterized by peripheral neuropathy, a global confusional state, retrograde amnesia, and confabulation).
Vitamin B12 deficiency (choice C) causes a macrocytic anemia. Patients may complain of a sore tongue or weight loss. Neurologic manifestations, including weakness and ataxia from demyelination, are the most worrisome. Causes include pernicious anemia, gastrectomy, and ileal abnormalities.
Vitamin D deficiency (choice E) causes disorders of bone mineralization, namely rickets in children and osteomalacia in adults.
A 40-year-old man with a history of type V hyperlipoproteinemia is brought to the emergency department 3 hours following the abrupt onset of severe deep epigastric pain, nausea, and vomiting. The pain is steady and radiates to the back. The patient is agitated and has cool, clammy skin. His temperature is 38.5 C (101 F), blood pressure is 100/70 mm Hg, pulse is 110/min, and respirations are 22/min. Abdominal examination reveals tenderness in the upper abdomen, without guarding. A plain x-ray film shows an air-filled intestinal loop in the left upper quadrant. Laboratory investigations:
Glucose: 150 mg/dL
LDH: 150 U/L
ALT: 90 U/L
AST: 80 U/L
Amylase: 120 U/L
Lipase: 30 U/L
Calcium: 7 mg/dL
C-reactive protein: 1.2 mg/dL
Which of the following is the most likely diagnosis?
(A) Acute cholecystitis
(B) Acute hepatitis
(C) Acute pancreatitis
(D) Bowel perforation
(E) Mesenteric ischemia
(F) Ureteral lithiasis
Respuesta: C
The correct answer is C. Although the whole clinical presentation is characteristic of acute pancreatitis, normal or slightly elevated serum levels of pancreatic enzymes seem to contrast with such a diagnosis. Types I and V hyperlipoproteinemia are rare conditions predisposing to acute pancreatitis (the two most frequent are cholelithiasis and alcoholism). However, hypertriglyceridemia itself may often falsely depress amylase and lipase levels in the presence of otherwise typical clinical features of pancreatitis. Note, however, other classic laboratory and radiologic signs of acute pancreatitis present in this case: neutrophilic leukocytosis, hyperglycemia, hypocalcemia, elevated C-reactive protein, and the “sentinel loop” (airfilled loop of small bowel in the left upper quadrant). The latter parameter is often used as a radiologic marker of pancreatic damage.
Acute cholecystitis (choice A) is associated with gallstones in the great majority of cases. Often, it develops when a stone occludes the cystic duct. Severe pain in the right upper quadrant or epigastrium and leukocytosis are present, but none of the other signs characteristic of acute pancreatitis are seen.
Acute hepatitis (choice B) is associated with increased levels of serum aminotransferases. Pain is relatively mild compared with the extreme pain of acute pancreatitis. Jaundice is often present, although pancreatitis may also cause mild elevation of direct bilirubin because the pancreas becomes swollen and the common bile duct is blocked.
Bowel perforation (choice D) also presents with a dramatic clinical picture of pain of sudden onset, shock, and rigid abdomen. Pancreatic enzymes may be elevated. A plain x-ray film taken in upright position reveals air underneath the diaphragm.
Mesenteric ischemia (choice E) due to cardioembolism or artherosclerosis of mesenteric vessels presents with acute abdominal pain that is typically out of proportion to physical examination findings. The typical patient is over 50 years old and presents with acute left-sided abdominal pain that begins in the left iliac fossa, with nausea, vomiting, diarrhea, and abdominal guarding. The patient may have had similar previous episodes, or there may be associated symptoms of cardiovascular disease. Plain films show thickened bowel walls, indicating a paucity of gas in the intestines. Specific radiologic signs are pneumatosis intestinalis (i.e., submucosal gas), bowel wall thumbprinting, and portal vein gas. Although patients with hypertriglyceridemia are at risk for cardiovascular diseases, the most likely cause of this patient’s symptoms is acute pancreatitis.
Ureteral lithiasis (choice F) is in the differential diagnosis of conditions mimicking acute pancreatitis. However, the pain is often referred to the flank region and radiates toward the ipsilateral perineum. Gross or microscopic hematuria is usually present. Pancreatic enzymes are not elevated, and neutrophilic leukocytosis is absent.
An 18-year-old man has had rhinorrhea and a sore throat for 2 days. He has no significant past medical history. His temperature is 39.3 C (102.6 F), pulse is 110/min, and respirations are 20/min. He has tender anterior and posterior cervical lymphadenopathy and an erythematous pharynx with white exudates on the tonsils. The remainder of his examination is normal. Which of the following is the most likely causal organism?
(A) Candida albicans
(A) Candida albicans
(B) Haemophilus influenzae
(C) Staphylococcus aureus
(D) Streptococcus pneumoniae
(E) Streptococcus pyogenes
Respuesta: E
The correct answer is E. This patient has the classic triad of fever, exudative pharyngitis, and cervical lymphadenopathy, strongly suggestive of streptococcal infection (group A beta hemolytic Streptococcus).
Candida albicans (choice A) rarely causes the above clinical scenario. It is seen commonly in immunosuppressed patients, diabetics, and those recently on antibiotics. It causes characteristic white patches of exudate on mucosa.
Haemophilus influenza (choice B), Staphylococcus aureus (choice C), and Streptococcus pneumoniae (choice D) rarely cause exudative pharyngitis.
Due to a recent and sudden death of a rival college football player, a local university wishes to implement changes in its health care policies. The school is particularly concerned about the risk for sudden cardiac death in players with previously undiagnosed heart conditions. A preparticipation evaluation is to be performed on all of the school’s athletes. Which of the following is considered the most cost-effective method of screening young athletes at risk for sudden cardiac death?
(A) Careful medical history and examination
(B) Chest x-ray
(C) Echocardiography
(D) Exercise electrocardiography
(E) Resting electrocardiography
Respuesta: A
The correct answer is A. Sudden cardiac death (SCD), defined as any unexpected death of proven cardiac origin, is a rare event in young, competitive athletes. However, it raises the question of which preparticipation screening methods should be used for prevention. A consensus document published by the American Heart Association in 1996 (Circulation 1996; 94:850) indicates that the most feasible and cost-effective approach is to perform a careful medical history (including personal and family history) and cardiac examination to identify subjects at risk. Pertinent histories, cardiac auscultation, and assessment of exercise-induced symptoms are all essential to primary prevention of SCD in the athletic population.
Chest x-ray (choice B) would not be an adequate screening test to detect cardiac abnormalities that may result in sudden death.
Echocardiography (choice C) is certainly an effective test to demonstrate cardiac abnormalities, such as left ventricular hypertrophy or valvular disease, but its cost as a preparticipation screening in all competitive athletes would be exorbitant.
Both exercise cardiography (choice D) and resting cardiography**(choice E) **would also result in excessive costs.
A 20-year-old male college student is participating in the New York City Marathon and collapses one third of the way through the race. He is a well developed, athletic man who frequently plays basketball and tennis. He has no past medical history, except for a tonsillectomy at 9 years of age. There were no symptoms before he collapsed to the ground and lost consciousness. The patient is immediately rushed to the nearest emergency room but is pronounced dead on arrival. Which of the following is the most likely underlying cause of his sudden death?
(A) Aortic stenosis
(B) Arrhythmogenic right ventricular dysplasia
(C) Coronary anomalies
(D) Hypertrophic cardiomyopathy
(E) Isolated left ventricular hypertrophy
(F) Myocarditis
(G) Ruptured aorta
Respuesta: D
The correct answer is D. A fatal arrhythmia is the immediate cause of demise in sudden cardiac death (SCD), but the underlying conditions are extremely variable. Nonatherosclerotic causes are prevalent in the young population, but coronary artery disease becomes more frequent in athletes older than 40. Hypertrophic cardiomyopathy has been found in approximately ⅓ of cases of SCD in young athletes who present with SCD. This condition is frequently hereditary (hence the need for a careful family history) and may manifest with arrhythmias, chest pain, and signs of subaortic stenosis. Coronary anomalies (choice C), including atherosclerotic changes, represent the second most frequent cause of SCD in competitive athletes.
Aortic stenosis (choice A), arrhythmogenic right ventricular dysplasia (choice B), isolated (and otherwise unexplained) left ventricular hypertrophy (choice E), myocarditis (choice F), and ruptured aorta (choice G) are rare causes of SCD. Some studies have shown that an increased myocardial mass, per se, is a risk factor for SCD, even without coexisting pathologic changes.
A seriously ill AIDS patient is admitted to a hospital. He has multiple infections, including Pneumocystis carinii pneumonia, pulmonary cytomegalovirus infection, and candidiasis of the esophagus and possibly other sites. Screening chemistry studies are drawn, including electrolytes. Which of the following abnormalities would be most likely seen in this setting?
(A) Hyperkalemia
(B) Hypermagnesemia
(C) Hypocalcemia
(D) Hyponatremia
(E) Hypophosphatemia
Respuesta: D
The correct answer is D. You should be aware that roughly half of all hospitalized AIDS patients have hyponatremia. There are many reasons for abnormal sodium metabolism in seriously ill AIDS patients, who may have multiple organ systems involved with the disease. Some of the drugs these patients receive impair renal water excretion, hypotonic fluids may be administered during the course of therapy, and they may also have impaired renal function.
Cytomegalovirus or mycobacteria may cause destructive adrenalitis, or ketoconazole may impair adrenal glucocorticoid and mineralocorticoid synthesis. Pulmonary and CNS infections may induce the syndrome of inappropriate ADH secretion (SIADH). All these causes, often more than one in an individual case, contribute to the high incidence of hyponatremia in AIDS patients. If a specific cause can be identified and ameliorated, that will often improve the hyponatremia. Otherwise, fluid restriction is used for mild abnormalities; administration of hypertonic saline can be used to (slowly) correct more severe hyponatremia.
Disorders of potassium (choice A), magnesium (choice B), calcium (choice C), and phosphate (choice E) can occur but are much less common than disorders of sodium in AIDS patients.
A 31-year-old man is admitted to the hospital for suspicion of gastrointestinal bleeding. He has no significant past medical history but takes daily nonsteroidal antiinflammatory agents for pain in his knee. He presented to the hospital 6 hours ago after he noticed melanotic stools while at home. He is observed to have copious bright red blood per rectum. On physical examination, he is tachycardic, and his peripheral pulses are faint but present. His mental status appears normal. His extremities are cool to the touch. An intravenous line is placed. Which of the following is the most appropriate next step in management?
(A) Order an urgent type and cross match for blood
(B) Order an urgent hematocrit level
(C) Begin parenteral administration of large volumes of normal saline solution
(D) Begin parenteral administration of large volumes of colloid solution
(E) Place two additional large bore peripheral intravenous catheters
Respuesta: C
The correct answer is C. The management of acute hemorrhage is the same for almost all patients, regardless of the etiology. In this case, a patient who is actively bleeding with apparent marginal vital signs requires immediate restoration of blood pressure via fluid resuscitation with at least 3 L of crystalloid solution (normal saline or lactated Ringer’s) for every liter of blood lost. Tachycardia and hypotension are signs of a moderate to severe loss of blood volume, and no delay in initiating fluid therapy is warranted.
Ordering an urgent type and cross match for blood (choice A), although appropriate for the overall short-term management of this patient, is not an acceptable therapeutic option in the face of active bleeding with no fluid resuscitation in progress.
Ordering an urgent hematocrit level (choice B) is not useful in this case because hematocrit levels do not change for at least 4 hours after an acute bleed. In addition, it offers no therapeutic benefit and will not change the short-term management of this patient.
Beginning parenteral administration of large volumes of colloid solution (choice D) is not indicated in this case. In fact, colloid (albumin, Hetastarch, Hetaspan) is rarely indicated for fluid resuscitation since it may actually precipitate pulmonary edema. The only clear indication for colloid is in the therapy of early burns, as these patients have capillary leaks and are losing protein and albumin.
Placing two additional large bore peripheral IV catheters (choice E) is indicated only AFTER fluid resuscitation has been started through whatever peripheral or central access is available. The concept here is that large bore IV catheters or central catheters are required for aggressive fluid resuscitation, but not at the expense of delaying therapy through an already available, but smaller, route.
A 40-year-old man presents to the physician because of exertional dyspnea of recent onset. The patient appears comfortable at rest but says that he becomes short of breath with minimal effort. His temperature is 37 C (98.6 F), blood pressure is 162/65 mm Hg, pulse is 92/min with a rapid rise and fall, and respirations are 15/min. Chest examination reveals a prominent and laterally displaced apical impulse. A soft diastolic decrescendo murmur is heard along the left sternal border. Bilateral crackles are present at the lung base. The liver is not palpable, and there is no sign of peripheral edema. Which of the following is the most likely diagnosis?
(A) Aortic insufficiency
(B) Aortic stenosis
(C) Hypertrophic obstructive cardiomyopathy
(D) Infective endocarditis
(E) Mitral stenosis
(F) Ventricular septal defect
Respuesta: A
The correct answer is A. The patient manifests early left ventricular failure secondary to aortic regurgitation. The diastolic murmur in decrescendo along the left sternal border and the wide differential between systolic pressure and diastolic pressure are highly characteristic. The rapid rise and fall of peripheral pulses is known as Corrigan pulse. Similar hemodynamic changes (hyperdynamic circulation) may be observed in hyperthyroidism, large arteriovenous fistulas, beriberi, and patent ductus arteriosus.
Aortic stenosis (choice B) produces a “diamond-shaped” (crescendo-decrescendo) systolic murmur often radiating to the neck. In contrast to aortic regurgitation, aortic stenosis is associated with a narrow differential between systolic and diastolic pressures.
Hypertrophic obstructive cardiomyopathy (HOCM; choice C) may simulate aortic stenosis or coronary artery disease in symptoms. HOCM often presents with symptoms of exertional angina, dyspnea, and/or syncope. It is also widely known to be a cause of sudden cardiac death in young athletes. Diagnosis is usually made by recognizing the signs associated with outflow obstruction and the symptoms that are predominantly characterized by diastolic dysfunction. Characteristic findings on physical examination include a bifid carotid pulse, an S4 heart sound, and a harsh systolic crescendo-decrescendo located at the apex and left sternal border. The murmur increases with the Valsalva maneuver upon standing and with amyl nitrite, and it decreases with sudden squatting, leg raising, and handgrip exercises.
Infective endocarditis (choice D) may be accompanied by murmurs, usually secondary to valvular insufficiency, but systemic signs and symptoms of infection would be present.
Mitral stenosis (choice E) leads to a diastolic rumbling murmur audible at the apex or central precordium. An opening snap soon after S2 often precedes the murmur and is related to the forced opening imposed by the atrial contraction on rigid mitral valve leaflets.
Ventricular septal defect (VSD; choice F), the most frequent congenital cardiac anomaly, is associated with a pansystolic murmur at the left sternal border, often accompanied by a thrill.
A 42-year-old man with AIDS presents with a chief complaint of
persistent watery, non-bloody diarrhea. He is not on any medications
and denies recent travel or fever. On physical examination, his
abdomen is slightly bloated, with mild tenderness to palpation.
There is no occult blood in his stool. Stool samples for leukocytes, culture, ova, and parasites are all negative × 3. Which of the
following is the most appropriate next step in diagnosis?
(A) Abdominal CT
(B) Cytomegalovirus (CMV) antigenemia
(C) Modified acid-fast stain of the stool
(D) PPD test
(E) Small bowel biopsy
Respuesta:
The correct answer is C. In cases of HIV and persistent diarrhea, the differential diagnosis includes Cryptosporidium and Isospora. A fresh stool specimen should be examined for parasites using a modified acid-fast stain for both pathogens. These protozoal infections are the most common enteric protozoal infections in AIDS patients throughout the world.
Abdominal CT scan (choice A) may show changes in the colon wall consistent with inflammation and edema. However, the scan will probably not be helpful in the principal diagnosis of this patient’s condition.
CMV antigenemia (choice B) is an index of infection with CMV, which is common in an immunocompromised host such as a patient with HIV or one undergoing chemotherapy. GI symptoms are the result of ulcers in the esophagus, stomach, small intestine, or colon, which may cause rectal bleeding, bloody diarrhea, or perforation. Ganciclovir is used in the alleviation of symptoms.
The PPD test (choice D) is used to determine whether a patient has had prior exposure to Mycobacterium tuberculosis. Biopsy may show caseating granulomas. In a condition such as this, the patient would also complain of bloody diarrhea and weight loss.
If diagnostic studies are negative and diarrhea persists, patients should undergo endoscopy. Biopsy (choice E) of the duodenum or small bowel may show histologic evidence of cryptosporidial, microsporidial, mycobacterial, or cytomegalovirus (CMV) infection.
A previously healthy 23-year-old man comes to the physician because of a febrile illness that developed over a 2-day period. He has had temperatures to 39.4 C (102.9 F), with rigors, cough productive of mucopurulent sputum, and right chest pain. At this time, his temperature is 38.7 C (101.7 F), blood pressure is 132/80 mm Hg, pulse is 110/min, and respirations are 22/min. There is no cyanosis. Diminished tactile fremitus, dullness on percussion, and bronchial breathing are present in the right lower lung. A chest x-ray film shows consolidation of the right lower lobe. Microscopic examination of the sputum reveals gram-positive diplococci. The patient denies previous allergic drug reactions. Which of the following is the most appropriate pharmacotherapy?
(A) Cefazolin
(B) Erythromycin
(C) Penicillin
(D) Tetracyclines
(E) Trimethoprim-sulfamethoxazole
(F) Vancomycin
Respuesta: C
The correct answer is C. The symptomatology, x-ray evidence of lobar consolidation, and the finding of grampositive diplococci in the sputum all support a diagnosis of acute pneumonia due to pneumococcus. Microscopic examination of gram-stained sputum is more sensitive than culture in identifying pneumococcus. Penicillin is the agent of choice, administered orally (penicillin V) on an outpatient basis in uncomplicated pneumonia, or parenterally (IV penicillin G) for seriously ill patients.
Patients with a history of mild allergic reactions to penicillin, but without anaphylaxis or other serious reactions, should be treated with cefazolin (choice A).
Erythromycin (choice B) is a safe alternative to penicillin for pneumococcal pneumonia and covers the other common bacterial pathogens of community-acquired pneumonia, including (besides pneumococcus) Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella.
Tetracyclines (choice D), such as doxycycline, are the preferred drugs against Chlamydia pneumoniae and a good alternative to erythromycin for infections due to Mycoplasma pneumoniae and Moraxella catarrhalis.
The combination of trimethoprim and sulfamethoxazole (choice E) can be used as a second-line treatment in penicillin-allergic patients. It can also be used in case of pneumonia caused by highly penicillin-resistant strains of pneumococcus.
Vancomycin (choice F) is used against strains of pneumococcus highly resistant to penicillin or in case of severe allergic reaction to previous penicillin administration.
An otherwise healthy 22-year-old woman presents to her physician because of daily headaches over the past 2 weeks. The headaches have a vise-like character, seem to be more intense in the back of the head, and are often precipitated by emotional stress. Physical examination fails to disclose focal neurologic or visual deficits. Which of the following is the most appropriate initial step in patient care?
(A) Antidepressant drugs
(B) Calcium-channel antagonists
(C) Ergotamine-containing preparations
(D) Nonsteroidal anti-inflammatory drugs (NSAIDs)
(E) Sumatriptan
Respuesta: D
The correct answer is D. The clinical features of these headaches, with their characteristic vise-like quality, immediately suggest tension headaches, which are often associated with tightness of the neck muscles. Anxiety, fatigue, and noise may act as precipitating triggers. Exploration of underlying causes of anxiety is often useful, but a trial with aspirin or other NSAIDs may be sufficient in most cases. Tension headaches may show overlapping features with migraine.
Antidepressant drugs (choice A) are used to treat depression and its manifestations, including depression headaches. A full neuropsychiatric evaluation is necessary to begin such treatment.
Calcium-channel antagonists (choice B) are effective in decreasing the frequency of attacks of migraine, although they do not influence the intensity and duration of pain.
Ergotamine-containing preparations (choice C) and sumatriptan (choice E) represent the treatments of choice for acute migraine.
A 42-year-old woman presents to her physician because of recent urinary tract infections (UTIs). She has been on an unknown oral antibiotic chronically. She has a temperature of 37.2 C (99 F), and costovertebral angle tenderness is noted on the left side. A plain film of the abdomen reveals a radiopaque density filling the left renal pelvis and calyces. Which of the following is the most likely pathogen?
(A) Bacteroides fragilis
(B) Clostridium difficile
(C) Escherichia coli
(D) Proteus mirabilis
(E) Streptococcus bovis
Respuesta: D
The correct answer is D. The patient is experiencing recurrent UTIs associated with the presence of kidney stones (the radiopaque density in the renal pelvis and calyces). Urease-producing organisms, such as Proteus mirabilis, create a high urinary pH, contributing to the development of struvite kidney stones. The stone may cause obstruction and urinary stress, leading to infection. These stones are relatively soft and are usually amenable to percutaneous nephrostomy. Acetohydroxamic acid is an effective urease inhibitor. Pseudomonas and Providencia are less common urease-producing organisms that may cause struvite calculi.
Bacteroides fragilis (choice A) is associated with peritonitis in patients with an intra-abdominal abscess.
Clostridium difficile (choice B) is associated with pseudo-
membranous colitis.
Escherichia coli (choice C) is the most common cause of UTI.
Streptococcus bovis (choice E) is a nonenterococcal type of group D Streptococcus.
A 35-year-old woman has developed marked thickening of the skin of her hands, particularly her fingers. This thickening is accompanied by hyperpigmentation and is so marked as to limit the range of motion of her fingers. If this patient goes on to develop gastrointestinal problems, which of the following is most likely?
(A) Carcinoid tumor
(B) Duodenal peptic ulcer
(C) Esophageal dysfunction
(D) Pneumatosis cystoides intestinalis
(E) Sacculations of the colon
(F) Small bowel adhesions
Respuesta: C
The correct answer is C. The changes seen are those of scleroderma; if other organs become involved, the term systemic sclerosis is appropriate. This disease is characterized by diffuse fibrosis, degenerative changes, and vascular abnormalities. The most common significant internal involvement in these patients is esophageal dysfunction (which may predispose for reflux disease with risk of Barrett esophagus and cancer of the esophagus), which occurs as a result of replacement of the muscle of the esophagus by densely fibrotic, scar-like tissue. Other gastrointestinal complications include pneumatosis cystoides intestinalis (see below), sacculations of the colon and ileum (see below), biliary cirrhosis, and malabsorption secondary to bacterial overgrowth in the poorly functional small bowel.
Carcinoid tumor (choice A) does not have an increased incidence in systemic sclerosis.
Duodenal peptic ulcer (choice B) does not have an increased incidence in systemic sclerosis, although esophageal peptic ulcer, secondary to reflux problems, does.
Pneumatosis cystoides intestinalis (choice D) is an uncommon intestinal complication of systemic sclerosis in which degeneration of the muscularis mucosa allows the entry of air into the intestinal wall.
Sacculations of the colon (choice E) and ileum are broad outpouchings (very fat diverticula) that can sometimes complicate systemic sclerosis as a result of smooth muscle atrophy.
Small bowel adhesions (choice F) are not a feature of systemic sclerosis. They are commonly seen following abdominal surgery (e.g., for appendicitis) and in inflammatory conditions, such as Crohn disease. Small bowel adhesions typically present with symptoms of small bowel obstruction.
A 23-year-old man presents with a 3-month history of cough with blood-tinged sputum, shortness of breath, and gross hematuria. His temperature is 37.5 C (99.5 F), blood pressure is 158/94 mm Hg, pulse is 87/min, and respirations are 22/min. Examination reveals bilateral crackles at the lung base and mild edema of the palpebrae and feet. A chest x-ray film shows scattered pulmonary infiltrates in a distribution different from that present on a film taken 2 months ago. Examination of the sputum shows hemosiderin-laden macrophages but no microorganisms. Laboratory investigations show modest iron-deficiency anemia and no evidence of ANCA- type antibodies. Urinalysis shows gross hematuria and modest proteinuria. A renal biopsy demonstrates the presence of glomerulonephritis with linear deposition of IgG and complement components along the glomerular basement membrane. Which of the following is the most likely diagnosis?
(A) Churg-Strauss syndrome
(B) Goodpasture syndrome
(C) Idiopathic pulmonary hemosiderosis
(D) Postinfectious glomerulonephritis
(E) Wegener granulomatosis
Respuesta: B
The correct answer is B. Goodpasture syndrome is an autoimmune disease mediated by autoantibodies against a domain of type IV collagen in the basement membranes of both glomerular and alveolar capillaries. Consequently, the lungs develop hemorrhagic interstitial pneumonia manifesting with hemoptysis, whereas the kidneys develop necrotizing glomerulonephritis leading to nephritic syndrome (responsible for hematuria, pitting edema, and hypertension in this case). Linear deposition of IgG and complement along the basement membrane of the alveolar and glomerular capillaries is the pathognomonic feature. The latter alone is sufficient to support a diagnosis of Goodpasture syndrome. Corticosteroids and immunosuppressants are necessary to treat this serious condition.
Churg-Strauss syndrome (choice A) must be considered in the differential diagnosis. This condition is associated with blood and tissue eosinophilia and, frequently, with circulating ANCA, i.e., antineutrophil cytoplasmic antibodies (specifically p-ANCA).
Idiopathic pulmonary hemosiderosis (choice C) may appear similar to Goodpasture syndrome in its pulmonary manifestations- hemoptysis and pulmonary infiltrates-but this condition does not involve the kidneys nor is it associated with linear IgG deposition along basement membranes.
Postinfectious glomerulonephritis (choice D) most commonly follows a streptococcal infection and manifests with nephritic syndrome. Pulmonary manifestations are not present. Immunofluorescence of kidney biopsies reveals granular deposition of IgG and complement in the mesangium and glomerular basement membrane.
Wegener granulomatosis (choice E) enters the differential diagnosis of any condition manifesting with concomitant involvement of lungs and kidneys. It is characterized by a necrotizing granulomatous vasculitis and frequent presence of circulating c-ANCA.
