Ch 20 Robbins Flashcards
A 24-year-old man is awakened at night because of severe lower abdominal pain that radiates to the groin. The pain is very intense and comes in waves. The next morning, he notices blood in his urine. He has no underlying illnesses and has been healthy all his life. On physical examination, he is afebrile and has a blood pressure of 110/70 mm Hg. Laboratory studies show serum Na+, 142 mmol/L; K+, 4 mmol/L; Cl−, 96 mmol/L; CO2, 25 mmol/L; glucose, 74 mg/dL; creatinine, 1.1 mg/dL; calcium, 9.1 mg/dL; and phosphorus, 2.9 mg/dL. Urinalysis shows a pH of 7; specific gravity of 1.020; and no protein, glucose, ketones, or nitrite. The patient is advised to drink more water. He likes iced tea and consumes large quantities over the course of a hot summer. He continues to have similar episodes. Which of the following substances is most likely to be increased in his urine?
□ (A) Calcium oxalate □ (B) Cystine □ (C) Magnesium ammonium phosphate □ (D) Mucoprotein □ (E) Uric acid
(A) This patient has ureteral colic from the passage of a stone down the ureter. About 70% of all renal stones are composed of calcium oxalate crystals. Patients with these stones tend to have hypercalciuria without hypercalcemia. Uric acid stones and cystine stones are radiolucent and tend to form in acidic urine. Cystine stones are rare. Triple phosphate (magnesium ammonium phosphate) stones tend to occur in association with urinary tract infections, particularly infections caused by urease-positive bacteria, such as Proteus. Mucoproteins may coalesce into hyaline casts, which are too small to produce signs and symptoms.
A 47-year-old man has had a decreased urine output over the past 10 days. On physical examination, he is afebrile. Urinalysis shows 1+ proteinuria, 4+ hematuria, urobilinogen, and no glucose or ketones. Microscopic examination of the urine shows few WBCs and some RBCs with RBC casts. A renal biopsy is done, and the light microscopic appearance of a PAS-stained specimen is shown in the figure. What is the most likely clinical course in this patient?
□ (A) Acute renal failure that is reversible with supportive therapy
□ (B) Slowly developing renal failure that is unresponsive to corticosteroid treatment
□ (C) Rapidly progressive renal failure accompanied by hemoptysis
□ (D) Stable clinical course with intermittent hematuria
□ (E) Fever, leukocytosis, and endotoxic shock
(C) The figure shows glomeruli with epithelial crescents that are the morphologic correlates of rapidly progressive glomerulonephritis. Patients with this condition rapidly develop renal failure. One cause of rapidly progressive renal failure is Goodpasture syndrome, in which anti–glomerular basement membrane antibodies damage the glomeruli and the pulmonary alveoli. Damage to the alveoli results in hemoptysis. Acute tubular necrosis is potentially reversible. Focal segmental glomerulosclerosis is typically nonresponsive to corticosteroids. IgA nephropathy can have intermittent hematuria. Acute pyelonephritis is accompanied by fever and leukocytosis.
A 63-year-old man has noted increasing back pain for 7 months. He has had three respiratory tract infections with Streptococcus pneumoniae within the past year. On examination, he has pitting edema to his thighs. Laboratory studies show total serum protein, 9.6 g/dL; albumin, 3.5 g/dL; creatinine, 3 mg/dL; urea nitrogen, 28 mg/dL; and glucose, 79 mg/dL. Urinalysis shows proteinuria of 4 g/24 hr, but no glucosuria or hematuria. Abdominal CT scan shows enlarged kidneys without cysts or masses. A renal biopsy specimen shows deposits of amorphous pink material within glomeruli, interstitium, and arteries with H&E stain. Which of the following diseases is he most likely to have?
□ (A) Analgesic nephropathy □ (B) Diabetes mellitus □ (C) Membranous glomerulonephritis □ (D) Multiple myeloma □ (E) Systemic lupus erythematosus □ (F) Wegener granulomatosis
(D) There is a large amount of serum globulin, back pain from lytic lesions, immunosuppression with recurrent infections, and amyloid deposition enlarging the kidneys, all consistent with multiple myeloma. This AL amyloid deposition occurs in 6% to 24% of myeloma cases. Analgesic nephropathy can lead to tubulointerstitial nephritis and papillary necrosis. His serum glucose is not in the range for diabetes mellitus, and the pink deposits seen with nodular or diffuse glomerulosclerosis are not amyloid. The pink-staining, thickened capillary loops of membranous glomerulonephritis represent immune deposits, not amyloid. Systemic lupus erythematosus can result in immune deposits to produce “wire loop” thickening of glomerular capillaries.
A 58-year-old woman dies of a cerebral infarction. Laboratory findings before death included serum urea nitrogen level of 110 mg/dL and creatinine level of 9.8 mg/dL. At autopsy, the kidneys are small (75 g) and have a coarsely granular surface appearance. Microscopic examination shows sclerotic glomeruli, a fibrotic interstitium, tubular atrophy, arterial thickening, and scattered lymphocytic infiltrates. Which of the following clinical findings was most likely reported on the patient’s medical history?
□ (A) Rash □ (B) Hypertension □ (C) Hemoptysis □ (D) Lens dislocation □ (E) Pharyngitis
(B) These findings describe end-stage renal disease, the appearance of which is similar regardless of the cause (e.g., vascular disease or glomerular disease). With advanced renal destruction, hypertension almost always supervenes, even if it was absent at the onset of renal disease. Many such cases are referred to as “chronic glomerulonephritis” for want of a better term. A rash might have preceded the postinfectious glomerulonephritis. Hemoptysis occurs in Goodpasture’s syndrome. Lens dislocation is a feature of Alport syndrome. Pharyngitis with group A streptococcal infection may precede postinfectious glomerulonephritis.
For the past 6 months, a 72-year-old woman has noticed a slowly enlarging mass on the urethra. The mass causes local pain and irritation and is now bleeding. Physical examination shows a 2.5-cm warty, ulcerated mass protruding from the external urethral meatus. There are no lesions on the labia or vagina. A biopsy specimen of the lesion is most likely to identify which of the following?
□ (A) Embryonal rhabdomyosarcoma □ (B) Leiomyoma □ (C) Papilloma □ (D) Squamous cell carcinoma □ (E) Syphilitic chancre
(D) Carcinoma of the urethra is uncommon. It tends to occur in older women and is locally aggressive. An embryonal rhabdomyosarcoma (sarcoma botryoides) is a rare tumor that occurs in children. Benign tumors, such as a leiomyoma or papilloma, are typically well circumscribed and do not ulcerate. Syphilis produces indurated, painless lesions, rather than ulcerated, warty masses.
A 72-year-old man with Alzheimer disease dies of pneumonia. The gross appearance of the right kidney at autopsy is shown in the figure. The left kidney is normal in size, with a smooth cortical surface and a single 0.6-cm, fluid-filled cyst. The appearance of the right kidney is most suggestive of renal injury from which of the following?
□ (A) Ureteral obstruction □ (B) Benign nephrosclerosis □ (C) Analgesic abuse □ (D) Chronic pyelonephritis □ (E) Diabetes mellitus
(A) The ureteral, pelvic, and calyceal dilation results from long-standing obstruction leading to hydroureter and hydronephrosis. With benign nephrosclerosis, the kidneys become smaller and develop granular surfaces, but there is no dilation. The scarring that accompanies analgesic nephropathy or chronic pyelonephritis can be marked; it is associated with significant loss of renal parenchyma, but not with pelvic dilation. There are many renal complications of diabetes mellitus, mostly from vascular, glomerular, or interstitial injury, but there is no obstruction. In some patients, diabetes is complicated by a neurogenic bladder, and this can lead to functional obstruction. In such cases, both kidneys and ureters would be affected.
A 25-year-old man has a 5-year history of celiac sprue. Several days after a mild upper respiratory infection, he begins passing dark red-brown urine. The dark urine persists for the next 3 days and then becomes clear and yellow, only to become red-brown again 1 month later. There are no remarkable findings on physical examination. Urinalysis shows a pH of 6.5; specific gravity 1.018; 3+ hematuria; 1+ proteinuria; and no glucose or ketones. Microscopic examination of the urine shows RBCs and no WBCs, casts, or crystals. A 24-hour urine protein level is 200 mg. A renal biopsy specimen from the glomeruli of this patient is most likely to show which of the following alterations?
□ (A) Subepithelial electron-dense deposits
□ (B) Granular staining of the basement membrane by anti-IgG antibodies
□(C) Mesangial IgA staining by immunofluorescence
□ (D) Diffuse proliferation and basement membrane thickening
□ (E) Thrombosis in the glomerular capillaries
(C) IgA nephropathy, also known as Berger’s disease, can explain the presence of recurrent hematuria in a young adult. Nephrotic syndrome is not present, and mesangial IgA deposition is characteristic. The initial episode of hematuria usually follows an upper respiratory infection. IgA nephropathy occurs with increased frequency in patients with celiac disease. Granular staining of basement membrane with IgG antibodies denotes immune complex deposition, which may occur in postinfectious glomerulonephritis. The subepithelial deposits are seen on electron microscopy. Patients with these changes have nephritic syndrome. Diffuse proliferation and basement membrane thickening denote membranoproliferative glomerulonephritis. In this condition, IgG and C3 are deposited in the glomeruli. Glomerular capillary thrombosis is typical of hemolytic-uremic syndrome.
A 7-year-old boy is recovering from impetigo. Physical examination shows a few honey-colored crusts on his face. The crusts are removed, and a culture of the lesions grows group A Streptococcus pyogenes. He is treated with antibiotics. One week later, he develops malaise with nausea and a slight fever and passes dark brown urine. Laboratory studies show a serum antistreptolysin O titer of 1:1024. Which of the following is the most likely outcome?
□ (A) Development of rheumatic heart disease
□ (B) Chronic renal failure
□ (C) Lower urinary tract infection
□ (D) Complete recovery without treatment
□ (E) Progression to crescentic glomerulonephritis
(D) These findings are characteristic of poststreptococcal glomerulonephritis. The strains of group A streptococci that cause poststreptococcal glomerulonephritis differ from the strains that cause rheumatic fever. Most children with poststreptococcal glomerulonephritis recover, although perhaps 1% develop a rapidly progressive glomerulonephritis. Progression to chronic renal failure occurs more frequently in affected adults. A urinary tract infection is not likely to accompany poststreptococcal glomerulonephritis because the organisms that caused the immunological reaction are no longer present when symptoms of glomerulonephritis appear.
A 28-year-old, previously healthy man suddenly develops severe abdominal pain and begins passing red urine. There are no abnormalities on physical examination. Urinalysis shows a pH of 7; specific gravity 1.015; 1+ hematuria; and no protein, glucose, or ketones. The patient is given a device to use in straining the urine for calculi. The next day, the patient recovers a 0.3-cm stone that is sent for analysis. The chemical composition is found to be calcium oxalate. What underlying condition is most likely to be present?
□ (A) Gout □ (B) Acute cystitis □ (C) Diabetes mellitus □ (D) Primary hyperparathyroidism □ (E) Idiopathic hypercalciuria
(E) Calcium oxalate stones are the most common type of urinary tract stone. Approximately 50% of patients with calcium oxalate stones have increased excretion of calcium without hypercalcemia. The basis of hypercalciuria is unclear. Most uric acid stones are formed in acidic urine and are not related to gout. It is thought that these patients have an unexplained tendency to excrete acidic urine. At low pH, uric acid is insoluble, and stones form. Infections can predispose to the formation of magnesium ammonium phosphate stones. Diabetes mellitus is an uncommon cause of urinary tract lithiasis; although infections are more common in diabetics, most are not caused by urea-splitting bacteria. Hyperparathyroidism predisposes affected individuals to form stones containing calcium, but few patients with urinary tract stones have this condition.
A 56-year-old man has had back pain and has passed dark-colored urine for the past month. On physical examination, there is right costovertebral angle tenderness. Urinalysis shows a pH of 6; specific gravity 1.015; 2+ hematuria; and no protein, glucose, or ketones. Microscopic examination of the urine shows numerous RBCs, few WBCs, and no casts or crystals. The figure shows the representative gross appearance of the renal lesion. Which of the following laboratory findings is most likely to be reported?
□ (A) Elevated serum cortisol level □ (B) Elevated hematocrit □ (C) Ketonuria □ (D) Decreased creatinine clearance □ (E) Increased plasma renin activity
(B) The figure shows a renal cell carcinoma. About 5% to 10% of these tumors secrete erythropoietin, giving rise to polycythemia. Other substances can be secreted—among them corticotropin (adrenocorticotropic hormone), resulting in hypercortisolism in Cushing’s syndrome—but these cases are encountered less frequently than polycythemia. Ketonuria is a feature of type 1 diabetes mellitus, which is not associated with the development of renal neoplasms. Renal cell carcinomas are usually unilateral, and typically they do not destroy all of a kidney. There is no significant loss of renal function, and the serum urea nitrogen and creatinine levels are not elevated. Hypertension from hyperreninemia can occur in patients with some renal cell carcinomas, although this is uncommon. Ketonuria is seen in patients with decreased caloric intake and with type 1 diabetes mellitus. Renal cell carcinomas are usually unilateral and involve part of the kidney; renal failure is unlikely.
A 15-year-old boy has been passing dark-colored urine for the past month. On physical examination, he has bilateral sensorineural hearing loss and corneal erosions. Urinalysis shows a pH of 6.5; specific gravity 1.015; 1+ hematuria; 1+ proteinuria; and no ketones, glucose, or leukocytes. The serum creatinine level is 2.5 mg/dL, and the urea nitrogen level is 24 mg/dL. A renal biopsy specimen shows tubular epithelial foam cells by light microscopy. By electron microscopy, the glomerular basement membrane shows areas of attenuation, with splitting and lamination of lamina densa in other thickened areas. What is the most likely diagnosis?
□ (A) Acute tubular necrosis □ (B) Berger disease □ (C) Membranous glomerulonephritis □ (D) Diabetic nephropathy □ (E) Alport syndrome
(E) Alport syndrome is a form of hereditary nephritis. Hematuria is the most common presenting feature, but proteinuria is often present and may be in the nephrotic range. Patients progress to chronic renal failure in adulthood. Most patients have an X-linked dominant pattern of inheritance, but autosomal dominant and autosomal recessive pedigrees also exist. The foamy change in the tubular epithelial cells and ultrastructural alterations of the basement membrane are characteristic features. The genetic defect results from mutation in the gene for the α-5 chain of type IV collagen. Acute tubular necrosis follows ischemic or toxic injuries to the kidney and does not involve glomeruli. Berger disease, or IgA nephropathy, is a form of glomerulonephritis that does not produce tubular epithelial changes. Membranous glomerulonephritis generally produces a nephrotic syndrome and deposition of immune complexes in glomerular basement membrane. Nodular and diffuse glomerulosclerosis are typical changes in diabetic nephropathy.
A 32-year-old man has developed a fever and skin rash over the past 3 days. Five days later, he has increasing malaise and visits his physician. On physical examination, the maculopapular erythematous rash on his trunk has nearly faded away. His temperature is 37.1°C, and blood pressure is 135/85 mm Hg. Laboratory studies show a serum creatinine level of 2.8 mg/dL and blood urea nitrogen level of 29 mg/dL. Urinalysis shows 2+ proteinuria; 1+ hematuria; and no glucose, ketones, or nitrite. The leukocyte esterase result is positive. Microscopic examination of urine shows RBCs and WBCs, some of which are eosinophils. What is the most likely cause of this patient’s condition?
□ (A) Urinary tract infection □ (B) Congestive heart failure □ (C) Antibiotic use □ (D) Streptococcal pharyngitis □ (E) Poorly cooked ground beef
(C) These findings are typical of drug-induced interstitial nephritis. Various drugs can cause this condition, including sulfonamides, penicillins, cephalosporins, the fluoroquinolone antibiotics ciprofloxacin and norfloxacin, and the antituberculous drugs isoniazid and rifampin. Acute tubulointerstitial nephritis also can occur with use of thiazide and loop diuretics, cimetidine, ranitidine, omeprazole, and nonsteroidal anti-inflammatory drugs. The disease manifests about 2 weeks after the patient begins to use the drug. Elements of type I (increased IgE) and type IV (skin test positivity to drug haptens) hypersensitivity are present. WBCs, but not eosinophils, may be present in the urine of a patient with a urinary tract infection. Congestive heart failure can lead to acute tubular necrosis, but it is not associated with a rash or proteinuria. Poststreptococcal glomerulonephritis could account for the proteinuria and hematuria seen in this patient, but not for the rash because the strains of group A β-hemolytic streptococci that cause a skin infection precede by weeks the development of glomerulonephritis. Hemolytic-uremic syndrome can occur after ingestion of strains of Escherichia coli that may be present in ground beef.
After eating a cheeseburger, French fries, and ice cream for dinner one night, a 6-year-old girl develops nausea, mild abdominal cramping, and a slight fever. Three days later, her parents notice that she is passing dark stools and dark urine and appears fatigued and weak. On physical examination, she has a temperature of 37.9°C, pulse of 88/min, respirations of 18/min, and blood pressure of 140/90 mm Hg. Scattered petechiae are present on the extremities. Laboratory findings show a serum creatinine level of 2.2 mg/dL and urea nitrogen level of 20 mg/dL. Urinalysis shows a pH of 6; specific gravity 1.016; 2+ hematuria; and no protein or glucose. A renal biopsy specimen shows small thrombi within glomerular capillary loops. Which of the following diseases is most likely to produce these findings?
□ (A) Postinfectious glomerulonephritis □ (B) Wegener granulomatosis □ (C) Hereditary nephritis □ (D) Hemolytic-uremic syndrome □ (E) IgA nephropathy
(D) Hemolytic-uremic syndrome is one of the most common causes of acute renal failure in children. It most commonly occurs after ingestion of meat infected with verocytotoxin-producing Escherichia coli, most often serotype O157:H7. The toxin damages endothelium, reducing nitric oxide, promoting vasoconstriction and necrosis, and promoting thrombosis. With supportive therapy, most patients recover in a few weeks, although perhaps one fourth progress to chronic renal failure. Postinfectious glomerulonephritis occurs several weeks after an infection, usually with group A β-hemolytic streptococci. Wegener granulomatosis is a vasculitis that most often occurs in adults. Hereditary nephritis may occur in childhood; it is progressive and is not related to vascular disease. An IgA nephropathy most often occurs in young adults; it is not accompanied by vascular changes.
The parents of a 6-year-old girl notice that she has become increasingly lethargic over the past 2 weeks. On examination by the physician, she has puffiness around the eyes. Her temperature is 36.9°C, and blood pressure is 100/60 mm Hg. Laboratory findings show a serum creatinine level of 0.7 mg/dL and urea nitrogen level of 12 mg/dL. Urinalysis shows a pH of 6.5; specific gravity 1.011; 4+ proteinuria; and no blood or glucose. The 24-hour urine protein level is 3.8 g. The child’s condition improves after glucocorticoid therapy. Which of the following findings by electron microscopy is most likely to characterize this disease process?
□ (A) Subepithelial electron-dense humps
□ (B) Reduplication of glomerular basement membrane
□ (C) Areas of thickened and thinned basement membrane
□ (D) Increased mesangial matrix
□ (E) Effacement of podocyte foot processes
(E) A child with nephrotic syndrome and no other clinical findings is most likely to have lipoid nephrosis, also called minimal change disease. The term minimal change disease reflects the paucity of pathologic findings. There is fusion of foot processes, which can be seen only by electron microscopy. Subepithelial electron-dense humps represent immune complexes and are seen in postinfectious glomerulonephritis. Variability of basement membrane thickening may be seen in Alport syndrome. The mesangial matrix is expanded in some forms of glomerulonephritis (e.g., IgA nephropathy) and other diseases, such as diabetes mellitus, but not in minimal change disease.
A 25-year-old woman experiences sudden onset of fever, malaise, and nausea. On physical examination, her temperature is 38.2°C, pulse is 85/min, respirations are 18/min, and blood pressure is 140/90 mm Hg. A routine urinalysis shows 1+ proteinuria, 4+ hematuria, and no ketones or glucose. RBC casts are seen on microscopic examination of the urine. A renal biopsy is performed, and light microscopic examination shows marked glomerular hypercellularity with neutrophils in glomerular capillary loops. Immunofluorescence microscopy shows granular deposition of IgG and C3 in glomerular capillary basement membranes. Electron microscopy shows electron-dense subepithelial “humps.” What is the most likely diagnosis?
□ (A) Goodpasture syndrome □ (B) Systemic amyloidosis □ (C) Membranous glomerulonephritis □ (D) Diabetes mellitus □ (E) Postinfectious glomerulonephritis
(E) Postinfectious glomerulonephritis is one of many causes of a nephritic syndrome characterized by hematuria and RBC casts. Most children recover completely, but one in six adults may progress to chronic renal failure. Some cases may occur after a streptococcal pharyngitis (poststreptococcal glomerulonephritis). In other cases, such as this one, the preceding infection is so mild that patients give no history. Goodpasture syndrome also may produce a nephritic syndrome, but there is linear deposition of antibody in the glomerular basement membrane. Amyloidosis of the kidney mainly produces proteinuria without hematuria, as does membranous glomerulonephritis. Nodular and diffuse glomerulosclerosis are characteristic of diabetic nephropathy.
A 77-year-old man has had increasing difficulties with urination for the past 2 years. He has difficulty starting and stopping the urine stream. On physical examination, his temperature is 37°C, and blood pressure is 130/85 mm Hg. The figure shows the representative gross appearance of the bladder. Which of the following laboratory findings is most likely to be reported in this patient?
□ (A) Positive ANA test result
□ (B) Urine culture positive for Mycobacterium tuberculosis
□ (C) Hemoglobin concentration of 22.5 g/dL
□ (D) Schistosoma haematobium eggs in urine
□ (E) Prostate-specific antigen level of 5 ng/mL
(E) This patient has bladder hypertrophy resulting from outlet obstruction. In an older man, this type of obstruction is most often caused by prostatic enlargement resulting from hyperplasia or carcinoma. Mild elevations in the prostate- specific antigen (PSA) level may occur in patients with prostatic hyperplasia, and greater increases in PSA suggest carcinoma. Autoimmune conditions may be associated with interstitial cystitis, but cystitis does not cause bladder neck obstruction. Bladder outlet obstruction can increase the risk of infection, typically with bacterial organisms such as Escherichia coli, not Mycobacterium tuberculosis. Polycythemia can be the result of a paraneoplastic syndrome, but urothelial malignancies are unlikely to produce this finding; renal cell carcinoma is a more likely cause. Schistosomiasis leads to chronic inflammation and scarring.
A 50-year-old woman with diabetic nephropathy receives a renal allograft. An episode of acute cellular rejection requires an increase in immunosuppressive therapy. She develops dysuria. On examination, she has suprapubic pain on palpation. A urinalysis shows hematuria. Cystoscopy is performed, and 3- to 4-cm soft, yellow, slightly raised mucosal plaques are seen. Biopsy specimens of these lesions are taken and microscopically show mucosal infiltration by foamy macrophages with abundant PAS-positive cytoplasmic granules and small, laminated mineralized concretions. Which of the following organisms is most likely to be found in her urine?
□ (A) Adenovirus □ (B) Candida albicans □ (C) Chlamydia trachomatis □ (D) Escherichia coli □ (E) Schistosoma haematobium
(D) This woman has a peculiar form of cystitis known as malacoplakia, when macrophages have reduced phagocytic function, and the concretions within macrophages are known as Michaelis-Gutman bodies. Malacoplakia is a reaction to chronic bacterial infections, usually Escherichia coli and Proteus species, and often in the setting of immunosuppression. The most common organism associated with cases of acute cystitis is E. coli. The other organisms listed are uncommon causes for cystitis and for malacoplakia.
A 26-year-old man is involved in a motor vehicle accident and sustains acute blood loss. He is hypotensive for several hours before paramedical personnel arrive. They stabilize the bleeding and transport him to a hospital, where he receives a transfusion of 3 U of packed RBCs. Over the next week, the serum urea nitrogen level increases to 48 mg/dL, the serum creatinine level increases to 5 mg/dL, and the urine output decreases. He undergoes hemodialysis for the next 2 weeks and then develops marked polyuria, with urine output of 2 to 3 L/day. His recovery is complicated by bronchopneumonia, but renal function gradually returns to normal. The patient’s transient renal disease is best characterized by which of the following histologic features?
□ (A) Glomerular crescents in Bowman space
□ (B) Interstitial lymphocytic infiltrates
□ (C) Arteriolar fibrinoid necrosis
□ (D) Nodular glomerulosclerosis
□ (E) Rupture of tubular basement membrane
(E) This patient’s history is typical of ischemic acute tubular necrosis, which is often accompanied by rupture of the basement membrane (tubulorrhexis). An initiating phase that lasts approximately 1 day is followed by a maintenance phase during which progressive oliguria and increasing blood urea nitrogen levels occur, with salt and water overload. This is followed by a recovery phase during which there is a steady increase in urinary output and hypokalemia. Eventually, tubular function is restored. Treatment of this acute renal failure results in recovery of nearly all patients. Crescents suggest a rapidly progressive glomerulonephritis that is unlikely to resolve. Interstitial infiltrates suggest a chronic tubulointerstitial process. Fibrinoid necrosis in arterioles is a feature of malignant nephrosclerosis, a serious condition that produces significant renal damage. Nodular glomerulosclerosis is a feature of diabetic nephropathy and is a progressive condition that leads to chronic renal failure.
A 60-year-old, previously healthy man sees his physician because he feels feverish and weak. He reports passing dark-colored urine on several occasions during the past month, but has no urinary frequency, dysuria, or nocturia. On physical examination, his temperature is 37.8°C, and blood pressure is 125/85 mm Hg. A dipstick urinalysis shows 4+ hematuria; 1+ proteinuria; and no glucose or ketones. Which of the following procedures is the most appropriate in management of this patient?
□ (A) Straining of urine for calculi □ (B) Urine microbiologic culture □ (C) Abdominal CT scan for renal mass □ (D) Collection of a 24-hour urine specimen for protein □ (E) Percutaneous renal biopsy
(C) Painless hematuria in an older adult suggests a renal neoplasm. The additional presence of constitutional symptoms, such as fever and weakness, should raise the suspicion of a renal cell carcinoma. Urinary tract calculi usually cause severe, colicky pain when they are passed. Urinary tract infections are not characterized by recurrent hematuria without fever or other signs of acute inflammation. Nephrotic syndrome, which manifests with proteinuria, typically is not associated with hematuria. A renal biopsy has a low yield in a patient without an acute-onset renal disease, and it is an ineffective way of diagnosing tumors.
A 49-year-old man goes to his physician for a checkup and is found on physical examination to have a blood pressure of 160/110 mm Hg, but no other abnormalities. Laboratory studies show serum glucose of 75 mg/dL, creatinine of 1.3 mg/dL, and urea nitrogen of 20 mg/dL. His plasma renin is elevated. CT angiography shows marked stenosis of his renal arteries. He is treated with an angiotensin-converting enzyme inhibitor. A week later, he has a headache for which he takes ibuprofen. Over the next day, his urine output decreases. A reduction in which of the following chemical mediators most likely caused his reduced urine output?
□ (A) Aldosterone □ (B) Histamine □ (C) Nitric oxide □ (D) Prostaglandin □ (E) Tumor necrosis factor
(D) This patient’s hypertension is due to renal vascular constriction, typical for renal arterial atherosclerosis. In the face of reduced renal blood flow, his glomerular filtration rate (GFR) is maintained by prostaglandin-mediated vasodilation of afferent arterioles and angiotensin II–mediated vasoconstriction of efferent arterioles. The angiotensin-converting enzyme inhibitor decreases efferent arteriolar vasoconstriction and decreases glomerular capillary perfusion pressure. Nonsteroidal anti-inflammatory drugs such as ibuprofen inhibit prostaglandin synthesis and lead to vasoconstriction that reduces renal blood flow and reduces GFR. Aldosterone is increased with increased renin and angiotensin production and leads to reduced sodium excretion. Histamine is a vasodilator from mast cell granules that plays a role in acute inflammatory processes, but not blood pressure regulation. Tumor necrosis factor plays a role in many inflammatory processes, but not renal blood flow. Nitric oxide is a vasodilator, but does not have a significant effect on capillary blood flow.
A 50-year-old woman has had fever and flank pain for the past 2 days. On physical examination, her temperature is 38.2°C, pulse is 81/min, respirations are 16/min, and blood pressure is 130/80 mm Hg. Urinalysis shows no protein, glucose, or ketones. The leukocyte esterase test is positive. Microscopic examination of the urine shows numerous polymorphonuclear leukocytes and occasional WBC casts. Which of the following organisms is most likely to be found in the urine culture?
□ (A) Mycobacterium tuberculosis □ (B) Mycoplasma hominis □ (C) Escherichia coli □ (D) Group A streptococcus □ (E) Cryptococcus neoformans
(C) The clinical features in this patient are typical of urinary tract infection, and Escherichia coli is the most common cause. The WBCs are characteristic of an acute inflammatory process. The presence of WBC casts indicates that the infection must have occurred in the kidney because casts are formed in renal tubules. Most infections of the urinary tract begin in the lower urinary tract and ascend to the kidneys. Hematogenous spread is less common. Mycobacterium tuberculosis causes the rare “sterile pyuria”; however, renal tuberculosis typically does not manifest as an acute febrile illness. Mycoplasma and Cryptococcus are rare urinary tract pathogens. Group A streptococcus is best known as an antecedent infection to poststreptococcal glomerulonephritis, an immunologically mediated disease in which the organisms are not present at the site of glomerular injury.
A 58-year-old, relatively healthy man sees his physician for a routine health maintenance examination. Physical examination shows mild hypertension. Laboratory findings show a serum creatinine level of 2.2 mg/dL and urea nitrogen level of 25 mg/dL. Microalbuminuria is present, with excretion of 250 mg/day of albumin. Two years later, he returns for a follow-up visit. He is now hypertensive and has a serum creatinine level of 3.8 mg/dL, urea nitrogen level of 38 mg/dL, and 24-hour urine protein level of 2.8 g. A renal biopsy is done; the light microscopic appearance of a PAS-stained specimen is shown in the figure. Which of the following laboratory findings is most likely to be abnormal in this patient?
□ (A) Anti–glomerular basement membrane antibody □ (B) ANA □ (C) ANCA □ (D) Antistreptolysin O □ (E) C3 nephritic factor □ (F) Hemoglobin A1c □ (G) Hepatitis B surface antigen
(F) The figure shows nodular and diffuse glomerulosclerosis, a classic lesion in diabetes mellitus. Patients with diabetes mellitus have an elevated level of glycosylated hemoglobin (HbA1c). Patients with type 1 diabetes mellitus may initially have microalbuminuria, which predicts development of future overt diabetic nephropathy. There is progressive loss of renal function. These patients are often hypertensive and have hyaline arteriolosclerosis. The presence of overt proteinuria suggests progression to end-stage renal disease within 5 years. Anti–glomerular basement membrane antibody is seen in Goodpasture syndrome, which manifests as a rapidly progressive glomerulonephritis. The ANA test is positive in
a variety of autoimmune diseases, most typically systemic lupus erythematosus, which can be accompanied by glomerulonephritis. The ANCA test is positive in some forms of vasculitis, such as Wegener’s granulomatosis, which can involve the kidneys. The antistreptolysin O titer is elevated after streptococcal infections, which may cause postinfectious glomerulonephritis. The C3 nephritic factor may be present in type II membranoproliferative glomerulonephritis (dense deposit disease). Some patients with membranous glomerulonephritis have a positive serologic test result for HBsAg.
A 20-year-old woman, G1, P0, who is in the third trimester, has felt minimal fetal movement. An ultrasound scan shows a markedly decreased amniotic fluid index characteristic of oligohydramnios. She gives birth to a stillborn male fetus at 33 weeks’ gestation. At autopsy, there are deformations resulting from marked oligohydramnios, including flattening of the facies, varus deformities of the feet, and marked pulmonary hypoplasia. Microscopic examination of the liver shows multiple epithelium-lined cysts and a proliferation of bile ducts. Which of the following best describes the appearance of the kidneys in this fetus?
□ (A) Bilaterally enlarged kidneys replaced by 1- to 4-cm, fluid-filled cysts
□ (B) Bilaterally shrunken kidneys with uniformly finely granular cortical surfaces
□ (C) Decreased overall size of the right kidney and normal-sized left kidney
□ (D) Irregular cortical scars in asymmetrically shrunken kidneys with marked calyceal dilation
□ (E) Marked bilateral renal pelvic and calyceal dilation with thinning of the cortices
□ (F) Normal-sized kidneys with smooth cortical surfaces
□ (G) Symmetrically enlarged kidneys composed of small, radially arranged cysts
(G) Autosomal-recessive polycystic kidney disease (ARPKD) most often occurs in children and may involve the liver; most cases have mutations in the PKHD1 gene encoding for fibrocystin expressed in kidney, liver, and pancreas. By contrast, autosomal-dominant polycystic kidney disease (ADPKD) manifests with renal failure in adults and involves PKD1 and PKD2 gene mutations encoding for polycystin proteins found in renal tubules. Some less common forms of ARPKD are accompanied by survival beyond infancy, and these patients develop congenital hepatic fibrosis. Enlarged kidneys with 1- to 4-cm cysts are characteristic of ADPKD in adults. Perhaps the most common renal cystic disease seen in fetuses and infants is multicystic renal dysplasia (multicystic dysplastic kidney), in which the cysts and kidneys are variably sized. This disease can be focal, unilateral, or bilateral; however, congenital hepatic fibrosis is not present. Small, shrunken, granular kidneys typify end-stage renal diseases in adults. For oligohydramnios to be present, both kidneys must be affected, not just one. Irregular cortical scars with pelvicaliceal dilation may represent hydronephrosis complicated by infection in chronic pyelonephritis, a process that occurs in adults. Dilation with calyceal thinning can occur with obstructions in utero, such as posterior urethral valves in males or urethral atresia in males or females; liver lesions are not present in these cases. A cause of oligohydramnios other than abnormalities of the urinary tract (e.g., leakage of amniotic fluid with premature and prolonged rupture of membranes) could be present if the kidneys appear normal, but in this case the distinctive finding of congenital hepatic fibrosis points to ARPKD.
A 65-year-old woman has experienced increasing malaise with nocturia and polyuria for the past year. On physical examination, her blood pressure is 170/95 mm Hg. Urinalysis shows a pH of 7.5; specific gravity 1.010; 1+ proteinuria; and no glucose, blood, or ketones. The tests for leukocyte esterase and nitrite yield positive results, and levels of serum urea nitrogen and serum creatinine are elevated. Her clinical course is characterized by worsening renal failure, and she dies of bronchopneumonia. At autopsy, the kidneys are shrunken but unequal in size, and have deep, irregular surface scars. On sectioning, the calyces underlying the cortical scars are blunted and deformed. What is the most likely cause of renal failure in this patient?
□ (A) Chronic glomerulonephritis □ (B) Essential hypertension □ (C) Reflux nephropathy □ (D) Autosomal-dominant polycystic kidney disease □ (E) Systemic lupus erythematosus
(C) This description of the gross appearance of the kidney is characteristic of chronic pyelonephritis, caused most often by reflux nephropathy. Typical features include coarse and irregular scarring resulting from ascending infection, blunting and deformity of calyces, and asymmetric involvement of the kidneys. The loss of tubules from scarring gives rise to reduced renal concentrating ability; the patient had polyuria with a low specific gravity of the urine. Chronic glomerulonephritis, benign nephrosclerosis (caused by essential hypertension), and systemic lupus erythematosus produce bilateral symmetric involvement, and the affected kidneys are shrunken and finely granular. Autosomal-dominant polycystic kidney disease is characterized by large cysts that replace the renal parenchyma and greatly increase the size of the kidneys bilaterally.
A 29-year-old woman sees her physician because she has had a fever and sore throat for the past 3 days. On physical examination, her temperature is 38°C. The pharynx is erythematous, with yellowish tonsillar exudate. Group A Streptococcus pyogenes is cultured. She is treated with ampicillin and recovers fully in 7 days. Two weeks later, she develops fever and a rash, and notices a slight decrease in urinary output. Her temperature is 37.7°C, and there is a diffuse erythematous rash on the trunk and extremities. Urinalysis shows a pH of 6; specific gravity 1.022; 1+ proteinuria; 1+ hematuria; and no glucose or ketones. Microscopic examination of the urine shows RBCs and WBCs, including eosinophils, but no casts or crystals. What is the most likely cause of her disease?
□ (A) Deposition of immune complexes with streptococcal antigens
□ (B) Hematogenous dissemination of septic emboli
□ (C) Renal tubular cell necrosis caused by bacterial toxins
□ (D) Hypersensitivity reaction to ampicillin
□ (E) Formation of antibodies against glomerular basement membrane
(D) These findings point to an acute drug-induced interstitial nephritis caused by ampicillin. This is an immunological reaction, probably caused by a drug acting as a hapten. Poststreptococcal glomerulonephritis is unlikely to be accompanied by a rash or by eosinophils in the urine. Acute pyelonephritis is an ascending infection; it is uncommonly caused by hematogenous spread of bacteria from other sites. Acute tubular necrosis can cause acute renal failure. It is caused by hypoxia resulting from shock or from toxic injury caused by chemicals such as mercury, and only rarely, if ever, by bacterial toxins. Anti–glomerular basement membrane antibodies occur in Goodpasture’s syndrome, with hemorrhages in lungs as well.
A 4-year-old girl has complained of abdominal pain for the past month. On physical examination, she is febrile, and palpation of the abdomen shows a tender mass on the right. Bowel sounds are present. Laboratory studies show hematuria without proteinuria. Abdominal CT scan shows a 12-cm, circumscribed, solid mass in the right kidney. A right nephrectomy is done; the gross appearance of the mass is shown in the figure. What is the most likely diagnosis?
□ (A) Angiomyolipoma □ (B) Interstitial cell tumor □ (C) Renal cell carcinoma □ (D) Transitional cell carcinoma □ (E) Wilms tumor
(E) Wilms’ tumor is the most common renal neoplasm in children, and one of the most common childhood neoplasms. A complex staging, grading, and molecular analysis formula, and surgery, chemotherapy, and radiation result in a high cure rate. The microscopic pattern of Wilms tumor (nephroblastoma) resembles the fetal kidney nephrogenic zone. Angiomyolipomas may be sporadic or part of the genetic syndrome of tuberous sclerosis. They may be multiple and bilateral and have well-differentiated muscle, adipose tissue, and vascular components. Renomedullary interstitial cell tumors (“medullary fibromas”) are generally less than 1 cm and are incidental findings. Renal cell carcinoma is rare in children, and the most common patterns are clear cell, papillary, and chromophobe. Transitional cell carcinomas arise in the urothelium in adults and microscopically resemble urothelium.
