A 57-year-old man, otherwise fine, is found to have low serum sodium on routine laboratory testing. His serum osmolality is low, but his urine osmolality is >150 mOsm/kg. Which of the following is most likely to be found on further evaluation?
Intrathoracic lesions may be benign or malignant, and the latter may secrete a substance similar to vasopressin. Bronchogenic carcinoma is the most common intrathoracic lesion causing SIADH
A 78-year-old man is brought to the hospital because of nausea and vomiting. On examination he appears dry, his abdomen is soft, and the JVP is not visible. His laboratory tests reveal hypernatremia and his calculated free water deficit is approximately 3 L. In what part of the normal kidney is most of the water reabsorbed from?
The largest volume of water is reabsorbed in the nephron at the proximal convolution. Maximally concentrated urine depends on ADH, which allows distal convoluted tubes and collecting ducts to become permeable to water.
A 64-year-old man is admitted for hematuria after slipping on an icy pavement. His physical examination is normal. A selective angiogram of the left kidney is shown in Fig. Which of the following is the most likely diagnosis?
The diagnosis is renal cell carcinoma. There is marked hypervascularity of the left kidney. The arteries are irregular and tortuous, following a random distribution. There are small vessels within the renal vein that indicate the blood supply of the neoplastic thrombosis involving the renal vein. The kidney is enlarged and abnormally bulbous in the lower pole. CT scans have dramatically decreased the need for arteriography in evaluating renal lesions.
A 64-year-old man presents with symptoms of malaise, shortness of breath, edema, and no urine output for 24 hours. His past medical history is not significant, and his only medication is daily aspirin. On examination his JVP is 4 cm, heart sounds are normal, lungs are clear, and the abdomen is soft. A Foley catheter is inserted into his bladder for 200 cc of urine, which is sent for urinalysis. His urine output still remains low. Which of the following is the most appropriate initial diagnostic test?
Renal ultrasound is an important test in the assessment of acute and chronic renal failure. The oliguria suggests that obstruction is a possible explanation for the renal failure. Imaging is very sensitive for obstruction, but if bladder obstruction secondary to a large prostate is suspected, bladder catheterization would be the first step.
A 68-year-old woman develops new symptoms of burning when voiding. She has no fever, chills, or back discomfort. Her urinalysis reveals numerous white cells and bacteria. Which of the following medical comorbidities is most likely to coexist in this patient?
Urinary tract infections (UTIs) are increased in diabetes mellitus as well as in pregnancy, sickle cell disease, polycystic disease, and structural abnormalities of the urinary tract.
A 28-year-old woman presents with a recent episode of coughing up some blood, frequent nosebleeds, and now decreased urine output. A nasal mucosa ulcer was seen on inspection. Her urinalysis is positive for protein and red cells consistent with a GN. The CXR shows two cavitary lesions and her serology is positive for antineutrophil cytoplasmic antibodies (ANCA). Which of the following is the most likely diagnosis?
Numerous diseases are associated with renal and pulmonary manifestations, including lupus, Goodpasture’s syndrome, and Wegener’s granulomatosis. Wegener’s is typically associated with antineutrophil cytoplasmic antibodies.
A42-year-old man notices leg and facial swelling but no other symptoms. His examination is pertinent for 3+ pedal edema including periorbital edema. A 24-hour urine collection reveals 5 g of proteinuria. Which of the following is the most likely diagnosis?
In addition to amyloid disease, other conditions associated with nephrotic syndrome are secondary syphilis, malaria, and treatment with gold salts. Minimal change nephrotic syndrome, focal glomerular sclerosis, membranous nephropathy, and membranoproliferative GN are the primary renal diseases that present as nephrotic syndrome.
A 74-year-old woman develops acute sepsis from pneumonia and is admitted to the intensive care unit because of hypotension. She is started on antibiotics, and her blood pressure is supported with intravenous normal saline. Despite this she remains oliguric and develops ARF. Her urinalysis has heme-granular casts and the urine sodium is 56 mEq/L. Which of the following is the most likely cause of her ARF?
ATN is a common complication of prolonged hypotension and ischemic injury to the renal tubules. Heme-granular “muddy brown” casts are consistent with ATN. Peritoneal dialysis is preferred with cerebral trauma as well as with severe heart failure because of risk of hemorrhage or hypotension with hemodialysis. In particular, peritoneal dialysis does not require any anticoagulation and is safer if head trauma has occurred.
A pregnant woman develops hypertension, edema, and proteinuria, at 34 weeks of gestation. Which of the following is not a risk factor for the development of this complication?
Diabetes mellitus, chronic hypertension, multifetal gestation, and prior preeclampsia are associated with preeclampsia. When toxemia occurs in the first trimester, however, hydatidiform mole must be considered. The clinical manifestations of severe preeclampsia include headache, epigastric pain, visual disturbances, and hypertension. HIV is not associated with preeclampsia unless there is a preexisting renal disease.
A 30-year-old man presents with hematuria. His examination is normal except for an elevated blood pressure of 164/94 mm Hg. An ultrasound of the kidneys reveals multiple renal cysts in both kidneys. His father had a similar condition. Which of the following is not associated with this syndrome?
RA is not associated with polycystic kidney disease. It has an autosomal dominant inheritance and about 50% develop renal failure by age 60 years. Cysts are also seen in the liver (more common) and pancreas. Also 5–10% of asymptomatic patients can have cerebral aneurysms. Renal transplantation is utilized in end-stage renal failure (ESRF). The transplanted kidney cannot be affected by the disease.
A 15-year-old boy develops renal colic. The stone is not recovered, but urinalysis reveals hexagonal crystals, and a cyanide-nitroprusside test on the urine is positive. Which of the following is the most likely diagnosis?
Cystinuria is a congenital disorder associated with decreased tubular resorption of cystine, arginine, ornithine, and lysine. Only cystine is insoluble and is the cause of renal calculi. The typical hexagonal crystals are most likely to be seen on an acidic early-morning urine specimen. A positive cyanide-nitroprusside screening test should be confirmed by chromatography.
A 29-year-old man is stable 1 year post-kidney transplant. Which of the following complications of transplantation is the most likely cause of death?
Increase in neoplasms in renal transplant recipients includes cervical carcinoma, lymphoma, and cutaneous malignancies. Osteoporosis and persistent hyperparathyroidism are other bony complications. Risk of infection is related to degree of immunosuppression. Nevertheless, the most common causes of death are cardiovascular and tend to occur earlier than in the general population.
A 37-year-old immunosuppressed patient with renal failure develops sepsis. Which of the following antibiotics, if used, would require a major reduction in dosage?
Amikacin and vancomycin are the other antibiotics that require dose reduction in renal failure. Newer antibiotics are often used instead of aminoglycosides to reduce the risk of renal damage.vvvvvv
A 63-year-old woman presents for routine evaluation. She has had diabetes for the past 12 years with complications of neuropathy and retinopathy. You decide to screen her for renal complications of diabetes. Which of the following findings is not compatible with diabetic nephropathy?
Red cell casts are not seen in diabetic nephropathy and suggest another acute GN process. Nephrotic range proteinuria, type IV RTA (hyporeninemic hypoaldosteronism), hypertension, and microalbuminuria are all complications of diabetic kidney disease.
A 24-year-old woman is dipstick positive for blood in her urine. This is repeated twice between menstrual periods and remains positive. Microscopic evaluation reveals RBCs, some of which are deformed and some in the form of casts. Which of the following is the most likely cause of the hematuria?
Isolated hematuria is usually of urologic cause (e.g., tumor, trauma, stone) but can also can be glomerular in origin. The finding of red cell casts or dysmorphic red cells (best appreciated by phase microscopy) suggests the source of bleeding is glomerular in origin.
A 63-year-old man becomes oliguric 2 days following an open cholecystectomy. Which of the following findings would suggest that prerenal ARF is a major factor in the etiology?
Although evidence of volume contraction cannot confirm prerenal ARF, as this can progress into intrinsic renal failure, it suggests that prerenal factors are contributing. In prerenal ARF, specific gravity is usually >1.020 and sodium concentration is <10 mmol/L. The fractional excretion of sodium relates sodium clearance to creatinine clearance and is more sensitive than direct measurements of sodium excretion. In prerenal azotemia, sodium is avidly resorbed from glomerular filtrate, but not in intrinsic renal azotemia because of tubular epithelial cell injury. Creatinine is resorbed less efficiently in both conditions. Therefore, the fractional excretion of sodium is 1% in intrinsic renal azotemia. Fractional excretion of sodium(%) = UNa/PCr PNa/UCr 100.
A 46-year-old woman with nausea and vomiting presents to hospital because of lightheadedness when standing and decreased urine output. She looks unwell; the blood pressure supine is 90/60 mm Hg and 80/60 mm Hg when standing. Her abdominal, heart, and lung examinations are normal. Which of the following laboratory values suggests prerenal azotemia in this patient?
The ratio of BUN/creatinine is usually 20 in prerenal azotemia.
A 19-year-old girl develops sudden-onset nonbloody diarrhea. She was previously well and is not taking any medications or traveled anywhere recently. Her abdomen is soft and nontender on examination, and the anion gap is normal.
She has a nonanion gap metabolic acidosis because of bicarbonate loss from the diarrhea. The anion gap is calculated as the sodium concentration minus the chloride plus the bicarbonate concentration. Other causes of bicarbonate loss with normal anion gap include proximal RTAand primary hyperparathyroidism.
A 75-year-old man develops acute confusion and drowsiness after a dental procedure. He has a history of severe chronic lung disease due to smoking. Earlier in the day, he had a tooth extraction and afterwards was given acetaminophen with codeine (Tylenol # 3) for pain relief.
Causes of acute respiratory acidosis include narcotic overdose, myasthenia gravis, airway obstruction, and trauma to the chest. Acute increases in PaCO 2 result in carbon dioxide narcosis. This starts with somnolence and confusion and can lead to coma. Asterixis may be present. Cerebral vasodilation may result in frank papilledema.
A 74-year-old woman has symptoms of shortness of breath on exertion and waking up at night. Her physical examination reveals a JVP at 8 cm, extra third heart sound, lung crackles, and pedal edema. She is started on furosemide 80 mg/day for heart failure, while further investigations are performed.
Diuretics are a common cause of metabolic alkalosis. The disorder can occur in volume expanded patients in whom the alkalosis is unresponsive to sodium chloride loading, as in primary hyperaldosteronism or volume contraction with secondary hyperaldosteronism, as in this case.
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