Módulo 4 Med. Interna Flashcards

Question

A 55-year-old white man presents to the emergency department with severe abdominal pain that has been radiating through to his back for the past 2 days. The man appears acutely ill and is sitting in a markedly bentover position, holding his arms over his abdomen. The patient states that this posture makes him feel slightly better, and comments that sudden movements and deep breathing make the pain worse. He has also been throwing up, even when there is nothing in his stomach. He describes the pain as “terrible” and begs for narcotics. On questioning, he admits to heavy drinking for the past 5 or 10 years. He denies use of street drugs. His temperature is 38.1 C (100.6 F), blood pressure is 85/60 mm Hg when lying down and 60/45 mm Hg when sitting, pulse is 120/min and regular, and respirations are 22/min and shallow. His lungs are clear to auscultation. Pressure on the upper portion of the abdomen intensifies the pain. Examination of the extremities reveals multiple bruises but no needle marks. The liver edge can be felt and has a nodular character. A complete blood count shows an erythrocyte count of 3.5 million/mm3 , white blood cell count of 18,000/mm3 with predominately neutrophils and increased band forms, and a platelet count of 200,000/mm3 . Which of the following is the most appropriate next step in diagnosis? (A) Blood urea nitrogen (B) Chest x-ray (C) Serum amylase level (D) Serum transaminase levels (E) Esophagogastroduodenoscopy

Answer 1

Respuesta: C The **correct answer is C**. This case is a fairly classic presentation of acute pancreatitis. These patients often have a history of either alcohol abuse or gallstone disease. Alcohol intake greater the 100 g/day favors precipitation of protein of the pancreatic enzymes within the ducts, which eventually (over a period of years) cause enough blockage to trigger pancreatitis. The pain described is typical of acute pancreatitis, but some patients with more chronic disease may have surprisingly little pain. Very early in the disease, the patient’s temperature may be subnormal, but fever usually develops within a few hours of onset. An elevated white count is usually present. The most helpful laboratory tests are serum amylase and serum lipase, elevation of which are considered strongly supportive of a diagnosis of pancreatitis. Blood urea nitrogen **(choice A)** is a marker for renal dysfunction. A chest x-ray film **(choice B)** might show pneumonia but would probably not be helpful in this patient with clear lungs. Serum transaminase levels **(choice D)** may very well be elevated in this alcoholic patient, but his most significant acute problem is his pancreatitis, not his probably damaged liver. Esophagogastroduodenoscopy **(choice E)** might show peptic ulcer disease, but severe pain would usually be seen only with perforation, and the patient would probably be vomiting blood in that setting.

Answer 2

Respuesta: C The **correct answer is C**. This patient is exhibiting the classic presentation of hyperthyroidism. Other signs and symptoms that may be seen include atrial fibrillation, nervousness, increased appetite, weight loss, frequent bowel movements, diplopia, conjunctival injection, and pretibial myxedema. The most common cause of hyperthyroidism is Graves disease (diffuse toxic goiter); in fact, infiltrative ophthalmopathy (as well as pretibial myxedema) is a specific autoimmune manifestation of Graves disease. The disease has an autoimmune basis, with antibodies directed against the TSH receptors, causing continuous thyroid gland stimulation. Euthyroid sick syndrome **(choice A)** causes asymptomatic thyroid hormone alterations, usually in patients with serious systemic disease. Follicular carcinoma of the thyroid **(choice B)** usually does not cause hyperthyroidism. Hashimoto thyroiditis **(choice D)** can cause transient hyperthyroidism early in its course, but this is uncommon compared with Graves disease. Subacute thyroiditis **(choice E)** usually causes striking thyroid gland tenderness and may cause transient hyperthyroidism.

Answer 3

Respuesta: B The **correct answer is B**. The clinical picture is consistent with a “locked-in” state that can be caused by central pontine myelinolysis. This condition consists of acute demyelination of the basilar pons, resulting in interruption of the corticobulbar (excluding the fibers to cranial nerve nuclei I-IV) and corticospinal tracts with preservation of sensory input. The patient can close his eyes by inhibition of the levator palpebrae muscle, innervated by the oculomotor nerve. One of the most common causes of this disorder is excessively rapid correction of hyponatremia. To prevent this complication, it is recommended that the increase in serum sodium level should not exceed 1 mEq/L/hr or 25 mEq/L within the first day of therapy. Alzheimer type 2 glia **(choice A)** refers to modified astrocytes that develop in patients with chronic liver failure. Hepatic encephalopathy is certainly a consideration in an alcoholic patient, but it would manifest with mental status changes and characteristic flapping tremor (asterixis) without paralysis. Cerebellar vermis atrophy **(choice C)** may be due to chronic alcoholism and is responsible for the ataxic gait frequently seen in chronic alcoholics. Subacute combined degeneration of the spinal cord **(choice D)** results in ataxia, numbness, and spastic paresis of the lower extremities. Wernicke encephalopathy **(choice E)** manifests with nystagmus, ophthalmoparesis, and confusion. Both disorders are related to thiamin deficiency.

Answer 4

Respuesta: A The **correct answer is A**. A tearing, excruciating chest pain that radiates to the back should always generate the clinical suspicion of aortic dissection involving the aortic arch. The patient presents with extreme signs of distress. Aortic insufficiency, with its associated diastolic murmur and widened pulse pressure, frequently develops. A discrepancy in blood pressure or pulse between the right and left arms is an additional supporting sign. Mediastinal widening is often seen on chest x-ray, but the diagnosis should be confirmed by CT or MRI scans. Hypertension is the most common predisposing factor, but Marfan syndrome is a classic condition associated with aortic dissection. Acute mediastinitis **(choice B)** is a rare infectious complication due to extension of suppurative processes from adjacent cervical organs (e.g., peritonsillitis, thyroiditis) or perforation of the esophagus or trachea. The patient has chest pain but lacks fever and other systemic signs of infections. The history of a recent dental abscess should not deceive you. Acute pericarditis **(choice C)** produces chest pain, which is gradual in onset and usually accompanied by a friction rub. If pericardial effusion is particularly abundant, cardiac tamponade **(choice D)** may ensue. The latter will result in acute signs and symptoms of cardiac failure, necessitating emergency pericardiocentesis to relieve the pressure on the heart. Myocardial infarction **(choice E)** is probably the most important differential diagnosis to consider in case of aortic dissection, but the absence of ECG changes suggesting myocardial ischemia argues against it in this patient.

Answer 5

Respuesta: A The **correct answer is A**. This is acute erosive gastritis, or “stress” gastritis, which is important to diagnose early because it can cause fatal gastrointestinal bleeding. Patients who develop this condition are usually already severely ill and very vulnerable to the problems of acute hemorrhage. Risk factors include severe burns, CNS trauma, sepsis, shock, and other organ system failure (respiratory, liver, renal, or multi-organ). Less severely ill patients may develop acute erosive gastritis as a complication of drug therapy (particularly, NSAIDs) or alcohol use. The pathogenesis of acute erosive gastritis in severely ill patients is thought to involve decreased mucosal defense mechanisms and localized mucosal ischemia, possibly compounded by acid hypersecretion (particularly in burns, CNS trauma cases, and sepsis), which promotes mucosal damage. Because of the potential seriousness of the condition, most intensive care units use measures such as early enteral feeding, IV H2 blockers, or antacids to prevent it. Chronic erosive gastritis **(choice B)** can be seen with drugs (aspirin and NSAIDs), Crohn disease, and viral infections. It is characterized by punctate lesions on the ridges of thickened rugal folds by endoscopy. Gastric atrophy **(choice C)** is a nonerosive lesion of the stomach with mucosal atrophy that can complicate long-standing gastritis of various etiologies. It can also occur in connection with autoantibodies to parietal cells, producing pernicious anemia. Nonerosive gastritis **(choice D)** is related to Helicobacter pylori infection characterized by inflammation through the entire mucosa. Superficial gastritis **(choice E)** is a nonerosive, and often asymptomatic, mild form of gastritis related usually to H. pylori infection.

Answer 6

Respuesta: H The **correct answer is H**. The patient is exhibiting the clinical picture of hypertensive emergency, in which striking elevation of blood pressure (diastolic values often >130 mm Hg) is associated with signs and symptoms of both cerebral damage (headache, confusion, and optic disk edema) and renal damage (proteinuria). Aggressive management is required to avoid serious complications or death and is aimed at gradually lowering blood pressure within 1 hour. IV infusion of sodium nitroprusside is the treatment of choice, but its administration should be carefully titrated to obtain the desired effect without excessively rapid reduction in blood pressure. Clonidine **(choice A)** and nifedipine **(choice F)** are oral antihypertensive agents that should be reserved for less severe cases of hypertension (so-called hypertensive urgencies), in which signs of cerebral or renal damage are not detectable. Enalaprilat **(choice B)** is the active form of enalapril. Its antihypertensive action is delayed; thus, it should be used only in conjunction with other, faster-acting agents. Esmolol **(choice C)** is a beta blocker drug that has been useful in treating hypertensive emergencies in the presence of myocardial ischemia. However, it should be combined with some other antihypertensive agent. Furosemide **(choice D)**, as well as other IV loop diuretics, may be useful in the presence of signs of cardiac failure or fluid retention, but their action is slow to manifest. Hydralazine **(choice E)** is mainly used in hypertensive crises affecting children and pregnant women. It may induce dangerous reflex tachycardia. Nitroglycerin **(choice G)**, administered by IV infusion, is less effective than nitroprusside but is useful in patients with manifestations of myocardial ischemia.

Answer 7

The correct answer is E. The polyglandular deficiency syndromes are autoimmune disorders that cause subnormal functioning of several endocrine glands concurrently. This patient has the type II variant, which has peak incidence at age 30 and always involves the adrenal cortex. Thyroid and pancreatic islet involvement, producing type 1 diabetes mellitus, are also common. In this patient, adrenocortical insufficiency is suggested by the cluster of serum sodium < 130 mEq/L, serum potassium > 5 mEq/L, plasma bicarbonate < 28 mEq/L, and BUN >20 mg/dL. Diabetes mellitus is suggested by the polyuria and the blood glucose of 380 mg/dL. Hypothyroidism is suggested by the elevated TSH. Patients with polyglandular deficiency syndrome, type II, may also present with transient hyperthyroidism secondary to destruction of follicles in the thyroid gland. Other features of the condition include antibodies directed against the target glands, particularly against cytochrome P450 adrenal cortical enzymes, and reduced systemic T- cell-mediated immunity. MEN type I (choice A) is characterized by tumors of the parathyroid glands, pancreatic islet cells, and pituitary gland. MEN type IIA (choice B) is characterized by medullary carcinoma of the thyroid, pheochromocytoma, and hyperparathyroidism. MEN type IIB (choice C) is characterized by multiple mucosal neuromas, marfanoid habitus, medullary carcinoma of the thyroid, and pheochromocytoma. Polyglandular deficiency syndrome type I (choice D) is characterized by onset in childhood or before age 35, hypoparathyroidism, adrenocortical failure, and gonadal failure; diabetes mellitus is not usually seen with this condition.

Answer 8

Respuesta: B The **correct answer is B**. These tears, called Mallory-Weiss lacerations, account for about 5% of cases of upper GI hemorrhage. They occur when the proximal part of the stomach is telescoped into the distal esophagus (stretching and tearing it) by severe vomiting, severe retching, or severe hiccups. The lacerations are usually superficial and often stop bleeding spontaneously. If the bleeding fails to stop spontaneously, the lacerations may be controlled endoscopically. The condition was initially described in alcoholics, but you should be aware that it occasionally occurs in many other types of patients as well. AIDS **(choice A)** can predispose for esophagitis due to viruses (CMV, herpes) or fungi (usually Candida). Chagas disease **(choice C)** can cause megaesophagus. Diabetes mellitus **(choice D)** can predispose for fungal (particularly Candida) esophagitis. Scleroderma **(choice E)** can involve the esophagus with fibrosis, leading to dysphagia.

Answer 9

Respuesta: E The **correct answer is E**. Liver adenoma is an infrequent benign tumor composed of hepatocytes arranged with the same lamellar pattern as the normal hepatic lobule. It is usually clinically silent and occurs most frequently in association with oral contraceptives or anabolic steroids. When symptomatic, its most common clinical presentation is rupture into the peritoneal cavity with consequent hemoperitoneum and shock. Abdominal pain **(choice A)** is a symptom of many hepatobiliary diseases, including hepatitis, carcinoma, and cholelithiasis. The pain of hepatic origin is presumed to result from stretching of the capsule as occurs in acute hepatitis. The pain of biliary origin derives from acute distention of the gallbladder, usually because of gallstones blocking the cystic or common bile duct. Jaundice **(choice B)** is not a manifestation of liver adenoma. Hemolytic disorders, diffuse hepatocellular damage, and obstruction of the biliary pathways are the most common conditions resulting in jaundice. Metastatic disease **(choice C)** is not a consequence of liver adenoma, which is a benign tumor. Liver adenoma, however, may be extremely similar histologically to well-differentiated hepatocellular carcinoma, so that one may be mistaken for the other. Portal hypertension **(choice D)** may result from prehepatic causes (thrombosis of the portal vein), hepatic causes (cirrhosis or other diffuse infiltrative conditions), and post-hepatic causes (obstruction of the hepatic veins or right-sided cardiac failure). Well-demarcated tumors, such as liver adenoma, do not lead to portal hypertension.

Answer 10

Respuesta: C The **correct answer is C**. The classic presentation, along with the hyperuricemia, makes gouty arthritis the most likely diagnosis. Nonsteroidal anti-inflammatory drugs (NSAIDs) are the treatment of choice of acute gouty arthritis. They are somewhat less specific than colchicine for gout but are better tolerated and work quickly. Allopurinol **(choice A)** is used in the intercritical period between attacks, not in acute attacks. Colchicine **(choice B)** is effective for acute gouty arthritis but is poorly tolerated at the high, frequent doses required for an acute attack. Steroids **(choice D)** can be used in an acute episode, but not before a trial with NSAIDs and/or colchicine is attempted. Probenecid **(choice E)** is a uricosuric agent used in the intercritical period, not during acute attacks, in patients who are under excreters of uric acid.

Answer 11

Respuesta: D The **correct answer is D**. Wegener granulomatosis is a vasculitis that affects the upper respiratory tract and paranasal sinuses, the kidneys, and the lungs. It is associated with dermatologic symptoms (subcutaneous nodules and purple papules). Antineutrophil cytoplasmic antibodies yielding a cytoplasmic immunofluorescence pattern (c-ANCA) are found in more than 90% of patients with Wegener granulomatosis. Antiribonucleoprotein **(choice A)** is found in high titer levels in mixed connective tissue disease (MCTD). MCTD is a distinct rheumatic syndrome characterized by overlapping clinical features of systemic lupus erythematosus, scleroderma, polymyositis or dermatomyositis, and rheumatoid arthritis. Elevated levels of serum IgE **(choice B)** might be seen in acute bronchopulmonary aspergillosis. Goodpasture syndrome is associated with anti-glomerular basement membrane antibody **(choice C)**. This disorder affects the kidney and lungs, rather than the lungs or paranasal sinuses. A positive p-ANCA **(choice E)** is seen in polyarteritis nodosa, a nongranulomatous vasculitis. Purple nodules can be seen in both polyarteritis nodosa and Wegener granulomatosis. Rheumatoid factor is positive **(choice F)** in many patients with rheumatoid arthritis, but this marker is nonspecific and may be positive in several other disorders.

Answer 12

Respuesta: C The **correct answer is C**. This is a dehydrated and malnourished patient with hypernatremia. The most probable cause is that she is no longer able to express thirst or hunger and cannot cooperate efficiently with caregivers when taking water or food. The most immediate goal of therapy is to replace water. The usual choice in this setting is 5% dextrose in water, which should be given relatively slowly to prevent glucosuria, followed by normal saline. This strategy would increase the salt-free water excretion and hypertonicity. Oral water administration **(choice A)** will work with physically and mentally competent people who have been water deprived (e.g., stranded in the desert). However, this strategy has obviously already failed in this patient (the nursing home was probably not deliberately trying to dehydrate her) and is not the best choice. IV 0.9% saline **(choice B)** by itself would not be used in this clinical setting. IV colloid and 0.9% saline **(choice D)** is used as the initial hydrating fluid in patients who are in shock secondary to dehydration, but is not needed in this patient with adequate blood pressure and symptomatic hypernatremia. IV distilled water **(choice E)** should never be given to patients-it will cause red cell lysis.

Answer 13

Respuesta: A The **correct answer is A**. This is Behcet syndrome. The laboratory findings are usually nonspecific indications of an inflammatory process (such as those illustrated in the question stem), so the diagnosis is usually established by the history (and may take months to years since not all features are typically present from the beginning). Characteristic features include painful oral ulcers, painful genital ulcers (in men, in women they may be painless), ocular disease (most often a relapsing iridocyclitis that causes pain and photophobia), skin lesions (papules, pustules, vesicles, or folliculitis), and mild arthritis of large joints. Other features that may be seen include CNS involvement and migratory thrombophlebitis. Herpes simplex infection **(choice B)** can cause oral and genital ulcers, but the Tzanck smear would probably be positive and arthritis would be unlikely. Neisseria gonorrhoeae infection **(choice C)** can affect both genitalia and joints, but does not usually cause ulcers. Psoriasis **(choice D)** can cause both skin lesions and arthritis, but the skin lesions are characteristically scale-covered plaques. Treponema pallidum infection **(choice E)** can cause ulcers (the chancre) but does not usually cause arthritis.

Answer 14

Respuesta: B The **correct answer is B**. This patient may have colon cancer. The weight loss, pallor, and anemia are indicative of a chronic bleed, supported by the stool positivity for occult blood. Risk factors for colon cancer include a positive history of colon cancer or adenomatous polyps in a first-degree relative and a personal history of adenomatous polyps. Since our suspicion of colorectal cancer is high, it would be helpful to detect the lesion and remove it if possible. Colonoscopy provides the most efficient modality with which to achieve this goal. A KUB **(choice A)** is usually a good modality for evaluating obstruction, which is a potential complication of colon cancer. This patient is not complaining of obstruction, and a KUB would not detect a soft tissue mass. Esophagoduodenoscopy **(choice C)** would be done to evaluate the patient for a source of upper gastrointestinal bleeding, such as ulcers, varices, or gastric cancer. Sigmoidoscopy **(choice D)** would be an effective screening test, but only 25 to 30% of colorectal cancers are detected by rigid sigmoidoscopy; the rate increases to 40 to 65% when flexible sigmoidoscopy is used. This patient has a high pre-test probability of having colorectal cancer, and since visualization of the entire colon will guide further action, sigmoidoscopy would be inadequate. Open laparotomy **(choice E)** might ultimately be needed if the patient undergoes colonic resection; however, it would be premature to immediately proceed to this option.

Answer 15

Respuesta: A The **correct answer is A**. The patient probably has carpal tunnel syndrome, which is caused by compression of the median nerve as it passes through the carpal tunnel in the wrist. The symptoms illustrated in the question stem are typical, as is the history of exacerbation of symptoms at night following heavy wrist use during the day. The test described is the Tinel test, which can be used to assess other superficial nerves as well. Milder cases of carpal tunnel syndrome may respond to rest and nonsteroidal anti-inflammatory drugs; more severe cases may require surgical decompression. Cubital tunnel syndrome **(choice B)** compresses the ulnar nerve at the elbow, producing numbness and paresthesias of the ring and little fingers. Radial tunnel syndrome **(choice C)** involves compression of branches of the radial nerve in the arm or forearm. It causes pain of the back of the forearm and hand, sometimes with wrist drop. Reflex sympathetic dystrophy **(choice D)** is pain and limited motion of the shoulder accompanied by ipsilateral involvement of the hand. Scapholunate ligament rupture **(choice E)** usually occurs during a fall onto an outstretched hand and causes pain in the mid-wrist.

Answer 16

Respuesta: C The **correct answer is C**. This patient presents with a lateral ankle sprain. Clinical assessment is usually sufficient to diagnose this condition, unless there are signs suggesting the presence of fracture. The drawer and talar tilt tests are used to assess ligament instability and confirm a diagnosis. A positive talar tilt test indicates injury to the calcaneofibular ligament, and a positive drawer test indicates injury to the anterior talofibular ligament. The history is also very important in clarifying the mode of traumatic injury. Currently recommended treatment for uncomplicated ankle sprains of mild-to-moderate degree includes protection of the injured joint by splinting or immobilizing boot; rest of the injured joint; ice application several times daily; compression by elastic wrap, and elevation of the limb to reduce edema (which gives the PRICE mnemonic). Adjuvant anti-inflammatory or analgesic treatment may be used. Patients with lateral ankle sprains should start rehabilitation early, usually after 24-72 hours of ankle rest. Treatment for acute ankle sprain with rehabilitation after 10 days of ankle rest **(choice D)** has been found to be unnecessary compared with shorter periods of immobilization. Referral to orthopedic specialist **(choice A)** is rarely necessary, unless there are complicating factors, such as associated injuries to other joints or fractures. Treatment with nonsteroidal anti-inflammatory drugs without ankle immobilization **(choice B)** is definitely inappropriate in any case of ankle sprain, however mild. X-ray examination **(choice E)** is indicated when there are signs suggestive of fractures, such as history of a snapping or popping sound at the time of injury, pain in the malleolar region, and tenderness on pressure on the lateral malleolus. It is recommended that patients older than 55 years should undergo routine x-ray control even in the absence of clinical signs of fractures because of the increased incidence of occult fractures in more advanced age.

Answer 17

Respuesta: B The **correct answer is B**. The clinical picture is highly suggestive of diabetes insipidus, a disorder due to deficiency of antidiuretic hormone (ADH) secretion from the posterior pituitary gland. Polydipsia is a consequence of polyuria (not an effect) because of abundant diuresis secondary to ADH deficiency. The vasopressin challenge test is given by administering desmopressin (a synthetic form) by the nasal route, and monitoring the urine output 12 hours before and 12 hours after administration. If the symptomatology is due to central diabetes insipidus, the patient will experience an immediate reduction in thirst and urine output. Diabetes insipidus may manifest in the third trimester of pregnancy or during the puerperium because of a circulating enzyme (vasopressinase) that degrades vasopressin. The enzyme is not effective against desmopressin. The disorder resolves spontaneously. Besides the high likelihood of noncompliance, advising the patient to reduce water intake **(choice A)** would expose her to severe dehydration and hypernatremia due to loss of water and resultant hemoconcentration. MRI studies of the pituitary-hypothalamic region **(choice C)** are performed to search for mass lesions that may be the underlying cause of central diabetes insipidus. These investigations should be performed after the diagnosis has received confirmation by a vasopressin challenge test. Compulsive water drinking may require psychiatric evaluation **(choice D)**, and may mimic diabetes insipidus, but this possibility should be undertaken once diabetes insipidus has been ruled out. In this particular case, the close temporal association with pregnancy and delivery makes the diagnosis of diabetes insipidus more likely. Evaluation of nephrogenic diabetes insipidus **(choice E)** is the next appropriate step if the patient does not respond to vasopressin challenge test. Nephrogenic diabetes insipidus, in fact, is due to resistance of renal tubules to the action of vasopressin. A hereditary X-linked form is known, usually associated with hyperuricemia. Acquired forms are associated with a variety of conditions, e.g., pyelonephritis, multiple myeloma, and chronic hypercalcemia.

Answer 18

Respuesta: C The **correct answer is C**. Acute renal failure (ARF) is a common occurrence in hospitalized patients. It is crucial to determine whether ARF is secondary to prerenal or renal causes. In the former case, the underlying cause is reduction of blood flow to normal kidneys, resulting in a decreased glomerular filtration rate. In the latter, intrinsic renal damage is the underlying etiology. Of the intrinsic causes of ARF, acute tubular necrosis is the most common. How can one distinguish between prerenal and renal forms of ARF? Sodium reabsorption is not impaired in prerenal azotemia, whereas creatinine reabsorption is deficient in both prerenal and intrinsic renal azotemia. Fractional excretion of sodium (FENa) is therefore a most useful parameter to distinguish between these two conditions. It can be calculated by the following formula: NaURINE × CrPLASMA/CrURINE × NaPLASMA, × 100. In prerenal azotemia, FENa < 1% because the undamaged renal tubules will avidly absorb sodium. In acute tubular necrosis, as well as other intrinsic renal causes of azotemia, damaged tubules will allow sodium to leak into urine, and FENa will be >1%. In this particular case, the calculation yields FENa = 1.6%. Gentamicin is the most nephrotoxic of the aminoglycoside antibiotics. Its toxicity usually manifests after 5-7 days of treatment. The most frequent manifestation of allopurinol toxicity **(choice A)** is a pruritic rash due to hypersensitivity. Vasculitis and hepatitis are other, albeit rare, adverse effects. Ampicillin toxicity **(choice B)** may manifest with renal damage, but usually in the form of acute interstitial nephritis, not acute tubular necrosis. Acute interstitial nephritis is associated with fever, rash, blood eosinophilia, and leukocyturia with eosinophils. Hyperuricemia **(choice D)** may cause acute tubular necrosis, but only when serum uric acid levels rise rapidly as a result of rapid cell turnover. This may develop with hematologic malignancies or germ cell neoplasms treated with chemotherapy. Uric acid levels are often very high (>20 mg/dL). Hypotension **(choice E)** is the underlying pathogenetic factor of most conditions leading to prerenal azotemia, such as hypovolemic, cardiogenic, or anaphylactic shock. Renal tubular function is preserved, but the fall in glomerular filtration rate results in oliguria/anuria and ARF. FENa is very low (< 1%). Clinical history is obviously an important aid in the differential diagnosis between prerenal and renal azotemia. Sepsis **(choice F)** is a frequent cause of prerenal azotemia when associated with shock. In this case, the laboratory data rule out this possibility.

Answer 19

Respuesta: B The **correct answer is B**. The presentation is classic for central retinal artery occlusion, which is a blockage of the central retinal artery by embolism or thrombosis that causes painless, sudden, unilateral blindness. Patients may have underlying atherosclerosis, endocarditis, or temporal arteritis. The retinal changes illustrated in the question stem are typical and are the result of a failure of blood to flow into the retina. Immediate treatment is imperative. Intermittent digital massage over the closed eyelids may dislodge the embolus and allow it to flow into a smaller blood vessel, where it will cause a small area of retinal ischemia. If this fails, anterior chamber paracentesis will also sometimes dislodge the embolus. Age-related macular degeneration **(choice A)** can also present with sudden, painless, unilateral blindness, but the fundus will show pigmentary changes with or without new vessel formation behind the retina. Central retinal vein occlusion **(choice C)** can also cause painless, unilateral blindness. However, it tends to develop a little more slowly than central artery occlusion, and the retinal vessels appear congested. Hypertensive retinopathy **(choice D)** does not usually cause sudden blindness. Retinitis pigmentosa **(choice E)** develops over a period of years, with loss of peripheral vision.

Answer 20

Respuesta: E The **correct answer is E**. This patient has mixed connective tissue disease. Clinically, it appears to be an overlap syndrome with features similar to rheumatoid arthritis, systemic lupus erythematosus, scleroderma, Sjögren syndrome, and polymyositis or dermatomyositis. It is now considered a separate disease because of a distinct autoantibody pattern, with very high levels of antibody directed against ribonucleoprotein. Rheumatoid agglutinins may also be present in high titers. Other antibodies characteristic of the individual diseases that mixed connective tissue disease mimics are usually absent or present only in low titers. The clinical presentation may be wildly diverse, depending on which disease pattern manifests first. With time, however, there should be clinical features suggestive of a variety of different autoimmune diseases. Mild disease may be controlled with measures similar to mild rheumatoid arthritis (salicylates, other NSAIDs, antimalarials, very-low-dose corticosteroids); more severe disease (which may be fatal with complications due to vascular lesions, renal failure, myocardial infarction, disseminated infection, or cerebral hemorrhage) usually requires large-dose steroids. Associate c-ANCA **(choice A)** with Wegener granulomatosis. Associate dsDNA **(choice B)** with systemic lupus erythematosus. Associate p-ANCA **(choice C)** with microscopic polyarteritis. Associate Scl-70 **(choice D)** with systemic sclerosis.

Answer 21

Respuesta: A The **correct answer is A**. Cigarette smoking is considered the principal preventable cause of disease in the U.S., and approximately 20% of adults in this country smoke. The guidelines of the U.S. Agency for Health Care Policy and Research (AHCPR) and the National Cancer Institute recommend that all primary care physicians identify smokers and advise them to quit smoking. Several studies have found that 10% of all smokers will quit smoking if they receive even a 3-minute advice to quit from a clinician. However, the very first step in the physician’s approach to a smoker is to establish his/her willingness to quit. With respect to smoking cessation, three stages have been identified: precontemplation, if there is no intention of quitting; contemplation, if there are some ideas but no clear plans of quitting soon; and action, if there is a definite intention of setting a quitting date. The next steps depend on the patient’s response. Trying to elicit a quitting date even if the patient appears unwilling **(choice B)** would be inappropriate. The physician should elicit a quitting date if the patient is already willing to do so, i.e., he/she is in the contemplation or action stage. The physician should discuss the reasons or obstacles that make a patient unwilling to stop if he/she is in the precontemplation stage. Information about risks of smoking should be provided. Prescribing nicotine patch and gum **(choice C)** is most useful in smokers who are nicotine dependent. Several questionnaires have been developed to establish nicotine dependence (the Fagerstrom questionnaire is probably the most widely used). Nicotine dependence is present if a patient smokes the first cigarette within 30 minutes after awakening, smokes more than 20 cigarettes daily, finds it difficult to refrain from smoking in places where smoking is prohibited, and continues to smoke even during illness. Determining nicotine dependence allows a physician to individualize treatment strategies by prescribing nicotine replacement therapy. Group behavior treatment **(choice D)** is mostly indicated for smokers who have already tried and failed to quit in the past. Recent studies have shown that combinations of intensive group counseling with nicotine replacement have the highest success rate (up to 40%) in obtaining long-term abstinence. Maximal specialized care with intervention of a psychiatry specialist **(choice E)** may be indicated for patients with a high degree of nicotine dependence associated with other forms of drug abuse (alcohol being the most frequent).

Answer 22

Respuesta: B The **correct answer is B**. The most probable etiology of bacterial endocarditis involving the tricuspid valve is illicit IV drug use, which can introduce skin organisms into the venous system that then proceed to attack the tricuspid valve. Staphylococcus aureus accounts for between 60 and 90% of cases of endocarditis in IV drug users. The endocarditis associated with congenital heart disease **(choice A)** typically involves either damaged valves or atrial or ventricular septal defects. The tricuspid valve is not particularly vulnerable. Rheumatic fever **(choice C)** most commonly damages the mitral and aortic valves, and tricuspid damage is usually less severe and seen only when the mitral and aortic valves are heavily involved. Consequently, secondary bacterial endocarditis involving only the tricuspid valve in a patient with a history of rheumatic fever would be unusual. Rheumatoid arthritis **(choice D)** is not associated with bacterial endocarditis. Systemic lupus erythematosus **(choice E)** can produce small, aseptic vegetations on valves (Libman-Sacks endocarditis) but is not associated with bacterial endocarditis.

Answer 23

Respuesta: A The **correct answer is A**. The clinical presentation is highly characteristic of epidural bleeding, which usually is of traumatic origin and most often results from rupture of the middle meningeal artery. The initial concussion leads to a brief loss of consciousness, which is followed by a lucid interval lasting several hours. As the epidural hematoma progressively enlarges and pushes the underlying brain, the patient becomes comatose again and may display signs of uncal herniation. The herniating uncus pushes on the third cranial nerve, producing ipsilateral fixed pupillary dilatation. Papilledema is usually a late sign and indicates cerebral edema. A calvarial fracture **(choice B)** would not cause such a severe neurologic state and evidence of uncal herniation unless associated with an intracranial hematoma. Intracerebral hypertensive hemorrhage **(choice C)** usually occurs spontaneously and develops within the brain parenchyma (most commonly in the basal ganglia). Loss of consciousness develops in approximately 50% of patients. Headache, vomiting, and variable neurologic deficits are present. Subarachnoid hemorrhage **(choice D)** characteristically manifests with sudden onset (thunderclap) of headache associated with vomiting and progressive impairment of consciousness. The most frequent cause is rupture of berry aneurysms. The clinical manifestations of a subdural hemorrhage **(choice E)** may vary depending on the severity and location. Cerebral atrophy is a predisposing condition, as it leads to “stretching” of bridging veins that connect the veins on the cerebral convexities with the superior sagittal sinus. Minimal trauma may then result in tearing of such veins. Impaired consciousness and/or focal neurologic deficits follow the traumatic event after an interval of days or weeks.

Answer 24

Respuesta: A The **correct answer is A**. Anticoagulation with heparin is the standard therapeutic first step for pulmonary embolus. Thrombolytic agents **(choices B and E)** still have a very limited role in the treatment of pulmonary embolus. They may be considered when overwhelming right-sided heart failure is life threatening, but bleeding remains a formidable potential complication; therefore, they are contraindicated after major surgery. When they are used, systemic administration **(choice E)** is as effective as direct delivery into the pulmonary artery **(choice B)**. Vena cava filters **(choice C)** are indicated only when pulmonary emboli recur while under anticoagulation, or if anticoagulation cannot be instituted. Surgical embolectomy **(choice D)** has the same restricted indications noted for the thrombolytic agents, and as a rule it is a major undertaking rarely feasible in a very sick patient.

Answer 25

Respuesta: J The **correct answer is J**. The triad of dementia, gait disturbances, and incontinence should immediately suggest normal pressure hydrocephalus as the underlying etiology (although such a complete clinical picture is often not present). MRI usually reveals an obvious discrepancy between the marked degree of ventricular dilatation (hydrocephalus) and the comparatively lesser extent of cortical atrophy. This cause of dementia is important because it is potentially treatable with a shunting procedure. However, long-standing cases lead to cortical atrophy and consequently become less responsive to shunting.

Answer 26

Respuesta: M The **correct answer is M**. The clinical picture of Pick dementia may be confused with other forms of dementia, especially Alzheimer disease, although in its classic presentation, flat emotional affect and language disturbances are predominant. However, MRI evidence of marked atrophy limited to the frontal and anterior temporal cortex supports a diagnosis of Pick disease. If a cortical biopsy is performed, it will show neuron loss with other characteristic neuronal changes, namely intracytoplasmic argyrophilic inclusions. Alzheimer disease **(choice A)** is the most frequent form of dementia and certainly should be suspected in all cases of gradually progressive memory loss accompanied by MRI evidence of diffuse cerebral atrophy. Dilatation of ventricles is secondary to loss of cerebral substance and is referred to as hydrocephalus ex vacuo. Chronic subdural hematoma **(choice B)** refers to a subdural collection of blood resulting from tearing of bridging veins. This may slowly enlarge and compress the underlying brain, occasionally resulting in dementia. The diagnosis is easily made by CT/MRI studies. Creutzfeldt-Jakob disease **(choice C)** causes a rapidly progressive form of dementia, accompanied by abnormal myoclonic movements and characteristic EEG changes. MRI does not reveal significant cerebral atrophy. Dementia pugilistica **(choice D)** is associated with a history of boxing. Cerebral atrophy is evident on MRI. Depression **(choice E)** is a major cause of pseudodementia, when intellectual impairment is not due to neurodegenerative changes. Other manifestations of depression are usually evident. Diffuse Lewy body disease **(choice F)** is now ranked among the most common causes of dementia. Neuron loss and Lewy bodies (the same as in Parkinson disease) are found in the substantia nigra and in several neocortical fields, leading to parkinsonism, dementia, and other neurologic manifestations such as visual hallucinations. Dementia is a very unusual presentation of intracranial tumors such as glioblastoma multiforme **(choice G)** and meningioma **(choice I)**. Glioblastoma multiforme is the most frequent primary malignant tumor, and meningioma is the most frequent benign tumor of the brain. Both can be detected by MRI. HIV encephalopathy **(choice H)** is referred to as AIDS-dementia complex or HIV-associated cognitive/motor complex. It manifests in AIDS patients with progressive deterioration of cognitive function and slowing of motor tasks (e.g., handwriting). MRI and CSF studies are necessary to exclude opportunistic infections or lymphoma. One quarter of Parkinson disease patients **(choice K)** presents with dementia. Three cardinal signs of Parkinson disease are resting tremor, rigidity, and bradykinesia, two of which are required for clinical diagnosis. Postural instability is the fourth cardinal sign and emerges late, usually after 8 years. Dementia also occurs late in the disease and affects short-term memory and visual spatial function. Pellagra **(choice L)** is due to nicotinic acid deficiency, which in its advanced stages manifests with the classic triad of dermatitis, diarrhea, and dementia. Vascular dementia **(choice N)** refers to dementia resulting from vascular causes, the most frequent of which are atherosclerosis of major cerebral arteries and hypertensive arteriolosclerosis. MRI would reveal multiple old infarcts in the cerebral cortex or lacunar infarcts in the basal ganglia, combined with variable white matter rarefaction. Wernicke encephalopathy and Korsakoff syndrome **(choice O)** are both seen in chronic alcoholics and are due to thiamine deficiency. The former consists of nystagmus, ataxia, and confusion; the latter consists of impaired memory with confabulation.