acute renal failure darren dreyfus, d.o. associates in nephrology, p.c. st. vincent’s health...

Acute Renal FailureAcute Renal Failure

Darren Dreyfus, D.O.Associates In Nephrology, P.C.St. Vincent’s Health System

Question 1Question 1


A previously healthy 74-year-old man is hospitalized with cough and chest pain. On physical examination, the blood pressure is 148/92 mm Hg, heart rate is 74/min, respiration rate is 18/min, and temperature is 37.8 oC (100 oF). The left lower lung field has scattered basilar crackles. The hematocrit is 34% and leukocytosis is present. The serum creatinine concentration is 2.3 mg/dL. Urinalysis shows a pH of 6.0, 1+ proteinuria, and no hematuria or ketonuria.


Which of the following is most useful in distinguishing acute from chronic renal failure in this patient?

(A) A previous hematocrit(B) A previous serum creatinine concentration(C) Blood urea nitrogen to creatinine ratio(D) Microscopic urinalysis(E) Renal ultrasonography

AnswerAnswer

Question 1 - AnswerQuestion 1 - Answer

Answer: BAlthough many evaluations remain to be

performed to establish a diagnosis in this patient with a decreased glomerular filtration rate, the first step must be to determine whether he has a history of renal insufficiency.

This allows the clinician to distinguish between acute and chronic renal failure

A previously elevated serum creatinine concentration can establish the diagnosis of chronic renal disease.


Ultrasonography provides information on size and symmetry of the kidneys and evidence for obstruction including hydronephrosis; however, renal ultrasonography may be normal in the presence of mild chronic renal disease.

The ratio of blood urea nitrogen to creatinine is not diagnostic of renal disease but when elevated suggests the possibility of pre-renal azotemia.

The previous hematocrit may suggest chronic renal disease, but it is also not diagnostic.

The urinalysis may be helpful in establishing the nature of the renal insufficiency but not its chronicity.


A 62-year-old man with a nonhealing diabetic ulcer is evaluated for preoperative clearance. He has a 10-year history of diabetes, hypertension, and severe peripheral vascular disease. He received insulin, amlodipine, and aspirin.

On physical examination, blood pressure is 140/90 mm Hg. No cardiopulmonary abnormality or volume overload is detected.


Which of the following is the most appropriate method to evaluate this patient’s renal function?

(A) A 24-hour urine collection for creatinine and volume

(B) Estimate creatinine clearance with a creatinine-based formula

(C) Measure the fractional excretion of sodium

(D) Measure the serum creatinine

AnswerAnswer


The staging of chronic kidney disease is based on the glomerular filtration rate. The estimated glomerular filtration rate is therefore paramount for correct diagnosis and treatment.

To minimize error and ensure widespread availability, the National Kidney Foundation suggests using creatinine-based formulae to estimate the glomerular filtration rate, such as the Cockcroft-Gault formula or the formula derived from the Modification of Diet in Renal Disease (MDRD) study.


Answer: BThe serum creatinine concentration alone is not

recommended for estimation of the glomerular filtration rate, but is a useful tool to monitor progression of chronic renal failure.

This concentration represents the balance between production of creatinine, which is relatively constant, and elimination through glomerular filtration, tubular secretion, and nonrenal pathways (usually negligible in healthy persons).

Muscle mass; comorbid conditions, such as malnutrition; and amputations can cause the serum creatinine concentration and the glomerular filtration rate to lower than expected for the degree of actual renal insufficiency.


A 24-hour urine collection by itself is not useful but when used to calculate a creatinine clearance can provide an acceptable estimate of glomerular function; however, daily and diurnal variation in creatinine excretion and problems with collection can cause error in the estimate of glomerular filtration rate.

The fractional excretion of sodium is not useful in estimating the glomerular filtration rate but is useful in the diagnosis of pre-renal azotemia in an oliguric patient.


A 65-year-old man is admitted to the hospital because of fever and dysuria.

Laboratory studies show a leukocyte count of 12,000/uL, a blood urea nitrogen level of 24 mg/dL, a serum creatinine concentration of 1.4 mg/dL, and pyuria.

Empiric treatment with TMP is started. Three days later, the pyuria and fever have resolved.

The leukocyte count is 10,000/uL, BUN is 24, and serum creatinine is 1.8 mg/dL. Urinalysis shows not leukocytes, casts, or crystals.


Which of the following is most likely the explanation for the rise in the serum creatinine from 1.4 mg/dL to 1.8 mg/dL?

(A) Acute interstitial nephritis(B) Acute phyelonephritis(C) Acute tubular necrosis(D) Obstructive uropathy(E) Reduced creatinine excretion

AnswerAnswer


Answer: ETrimethoprim and other organic cations, such

as cimetidine, competitively inhibit creatinine secretion in the distal tubule.

Although acute interstitial nephritis can occur secondary to treatment with TMP, it takes several days to evolve and is less commonly seen in the absence of other systemic allergic symptoms, such as eosinophils in the urine, rash, and fever.

Acute phyelonephritis is not likely, given that systemic symptoms resolved.


Obstructive uropathy can occur; however, it causes the glomerular filtration rate to decrease and, therefore, the BUN level would be elevated.

Unlike aminoglycosides or amphotericin B, TMP has not been associated with acute tubular necrosis and there is no evidence of acute tubular necrosis in the urinalysis such as muddy brown casts or renal tubular epithelial cells.


A 49-year-old man is evaluated because of dyspnea and hemoptysis of 3 days’ duration. He has had no fever or chills. He takes no medications.

On examination, blood pressure is 155/88 mm Hg, pulse rate is 90/min, respiratory rate is 18/min, and temperature is 37 oC (98.6 oF). Pulmonary examination reveals coarse crackles in the right mid-lung field. The remainder of the examination is normal.


Leukocyte count – 9200/uLHemoglobin – 8.7 g/dLSerum creatinine – 4.4 mg/dL (1.3 mg/dL

3 months ago)24-hour urine protein – 3.5 gUrinalysis – 4+ proteinuria, 3+

hemoglobinuria


Urine microscopy shows 25 to 50 erythrocytes/hpf, 5 to 1 leukocytes/hpf, dysmorphic erythrocytes, and erythrocyte casts. Kidney biopsy reveals proliferative glomerulonephritis with 50% of glomeruli having crescents. Immunofluorescence shows linear staining with IgG.


Which of the following provides the best description of his diagnosis?

(A) Acute interstitial nephritis(B) Acute tubular necrosis(C) Chronic renal failure(D) Rapidly progressive

glomerulonephritis

AnswerAnswer


Answer: DThe patient’s renal presentation is rapidly

progressive glomerulonephritis which consists of glomerulonephritis with nephritic urine sediment, acute renal failure developing over a few days to weeks, and glomerular crescents on renal biopsy.

In view of the immunoflourescence noted on renal biopsy, the most likely diagnosis is Goodpasture’s disease.


Acute interstitial nephritis is unlikely based upon the apparent lack of an inciting agent, such as an antibiotic, lack of fever and rash, and a biopsy finding that clearly shows a glomerular injury.

The patient has acute renal failure, but acute tubular necrosis would not produce a nephritic sediment.

Chronic renal failure is not likely based upon a normal creatinine 3 months ago.


A 43-year-old man is evaluated because of hemoptysis for 3 days’ duration. On examination, blood pressure is 155/72 mmHg, pulse rate is 90/min, respiration rate is 18/min, temperature is 37 oC (98.6 oF). Pulmonary examination reveals coarse crackles in the right mid-lung field. The remainder of the examination is normal.


Leukocyte count – 9200/uLHemoglobin – 8.7 g/dLSerum creatinine – 4.4 mg/dL (1.0 mg/dL

1 month ago)24-hour urine protein – 3.5 gUrinalysis – 4+ proteinuria, 3+

hemoglobinuria, and erythrocyte casts


Which of the following tests would most likely confirm the diagnosis of Goodpasture’s disease?

(A) Antinuclear antibody(B) c-ANCA(C) p-ANCA(D) Circulating antiglomerular basement

antibody(E) Serum C3 and C4 levels

AnswerAnswer


Answer: DThe syndrome of hemoptysis and rapidly

progressive renal failure due to a glomerulonephritis makes Goodpasture’s syndrome the most likely diagnosis.

In the differential diagnosis of rapidly progressive glomerulonephritis are lupus nephritis, Wegener’s granulomatosis, and infection-associated glomerulonephritis.

However, only Goodpasture’s disease is associated with circulating antiglomerular basement membrane.


Therefore, finding a circulating antibody against glomerular basement membrane in serum is most consistent with Goodpasture’s syndrome and makes the diagnosis almost certain.

A positive ANA and low serum complement support the diagnosis of systemic lupus erythematosus whereas c-ANCA correlates best with Wegener’s granulomatosis and p-ANCA with microscopic polyangiitis and Churg-Strauss syndrome.


A 71-year-old man with a 4-month history of non-Hodgkin’s lymphoma is evaluated in the emergency department because of polyuria, weakness, and lassitude of 3 days’ duration. His cancer was treated with rituximab, cyclosphosphamide, prednisone, vincristine, and doxorubicin, followed by radiation therapy.

On physical examination, blood pressure is 124/78 mm Hg, with no orthostatic changes, pulse rate is 96/min, respiration rate is 18/min, and temperature is 36.8 oC (98.2 oF). The remainder of the examination is unremarkable.


The serum creatinine concentraion, previously normal, is now 2.4 mg/dL. Urinalysis shows a pH of 6.0 and 1+ proteinuria, but no hematuria or ketonuria. No formed elements appear on microscopic examination.


Which of the following should be done next to determine the cause of this patient’s renal insufficiency?

(A) Calculate the ratio of blood urea nitrogen to creatinine

(B) Radioisotope renal scan(C) Renal biopsy(D) Renal ultrasonography(E) Volume repletion with .5 L of normal

saline, intravenously

AnswerAnswer


Answer: DThere are several potential causes of acute renal

failure associated with cancer and its treatment.The differential diagnosis in this case includes urinary

tract obstruction and radiation nephritis. Urinary tract obstruction must be ruled out, especially

in patients with cancer of the genitourinary tract or pelvic organs.

Lymphoma may involve the prostate and abdominal lymph or pelvic lymphadenopathy may obstruct the outflow of the bladder.

The ratio of blood urea nitrogen to creatinine is not a sufficiently sensitive measure on which to base clinical decision making in this case.


Renal scanning is most useful in evaluating asymmetric blood flow and yields valuable information in selected patients with evidence of renal arterial disease, which is not a consideration in this case.

There is no evidence of volume depletion, so intravenous normal saline is not indicated.

Renal biopsy, even with its relatively low risk, is an invasive procedure and is best deferred until later in the course following a non-invasive evaluation.


A 56-year-old man is evaluated for anorexia and a rash on his legs of 7 days’ duration. One week ago he was hospitalized and treated with intravenous penicillin for pneumococcal pneumonia. He did well and was sent home on the second day with a prescription for a 10-day course of oral penicillin. Serum creatinine concentration was 0.9 mg/dL


On physical examination today, his blood pressure is 130/90 mm Hg, with no orthostatic changes, pulse rate is 80/min, respiration rate is 12/min, and temperature is 39.0 oC (102.2 oF). A diffuse erythematous macular rash is found on the lower extremities from the ankles to the thighs. The remainder of the examination is normal.

Leukocyte count – 16,300/uLBUN – 46 mg/dLSerum creatinine – 3.4 mg/dLUrinalysis – pH 6.0 specific gravity 1.014, 1+

proteinuria, trace hematuria, no ketoneuria, 30 to 40 leukocytes/hpf


Which of the following is the most likely diagnosis?

(A) Acute interstitial nephritis(B) Acute pyelonephritis(C) Medium size-vessel vasculitits(D) Membranous glomerulonephritis(E) Rapidly progressive

glomerulonephritis


Answer: AThe clinical course of new renal insufficiency

with pyuria after treatment with antibiotics is most consistent with a diagnosis of acute interstitial nephritis.

In many cases, renal dysfunction improves when the offending agent is discontinued.

Vasculitis or rapidly progressive glomerulonephritis might be considered a possibility but lacks supporting evidence in finding no red blood cells or casts in the urine.


Acute pyelonephritis does not usually cause acute renal failure, particularly in the absence of symptoms such as fever and flank pain.

Membranous glomerulonephritis commonly presents as the nephrotic syndrome, for which there is no supporting evidence.


A 43-year-old woman with a 2-year history of HIV infection is evaluated because of back pain and new onset renal insufficiency of 30 hours’ duration.

Her HIV medications include zidovudine, lamivudine, and indinavir.

Six months ago, she developed type 2 diabetes and hypercholesterolemia and began treatment with rosiglitazone and atorvastatin.

On physical examination, blood pressure is 130/85 mm Hg, pulse rate is 88/min with no orthostatic changes, and temperature is 37.8 oF (100 oF). Other than 2+ lower pedal edema, the remainder of the examination is unremarkable.


BUN – 22 mg/dLSerum creatinine – 3.2 mg/dL (0.7 mg/dL

1 month ago)Serum uric acid – 9.0 mg/dLMicroscopic and dipstick urinalysis – 3+

blood, 1+ protein by dipstick. Muddy brown casts and tubular epithelial cells, but no erythrocytes, leukocytes or crystalluria



(A) Diabetic nephropathy(B) HIV-associated nephropathy(C) Nephrolithiasis(D) Rhabdomyolysis

AnswerAnswer


Answer: DThe hematuria on dipstick and lack of erythrocytes

on microscopy support a diagnosis of rhabdomyolysis.

The absences of urine crystals and erythrocytes argues against indinavir crystal nephrolithiasis.

The absence of proteinuria argues against HIV-associated nephropathy and diabetic nephropathy.

In addition, the short history of diabetes is inconsistent with a diagnosis of diabetic nephropathy which typically complicates diabetes of more than 10 years’ duration.


A 58-year-old woman is evaluated because of lethargy, mild nausea, and weakness for the past 2 weeks. Three months ago, the patient began taking oral calcium (1500mg/d) and 25-hydroxyvitamin D as treatment for osteoporosis. She has chronic hypertension controlled with metoprolol and asymptomatic pulmonary sarcoidosis.


On examination, the blood pressure is 140/80 mm Hg, pulse rate is 80/min, and temperature is 37 oC (98.6 oF). The remainder of the physical examination is normal. Hematocrit – 38% BUN – 34 mg/dL Serum creatinine – 2.2 mg/dL (1.0 mg/dL 3 months ago) Serum calcium – 12.8 mg/dL Serum phosphorus – 3.5 mg/dL Urinalysis – pH 5.5; specific gravity 1.010; no protein, cells,

or casts Serum protein electrophoresis – Normal Urine immunoelectrophoresis - Normal

AnswerAnswer


Answer: DHypercalcemia can cause acute renal failure by

interfering with renal concentrating function, leading to volume depletion; calcium deposition in the renal parenchyma, causing fibrosis and by direct hemodynamic effects, causing afferent arterial constriction.

In this patient, the latter cause is most likely. Elevated levels of Vitamin D lead to

hypercalcemia by increasing calcium absorption of calcium from the gut.

This probably was exacerbated by her recent high calcium and vitamin D dietary modifications.


Acute renal failure due to meyloma kidney is always associated with abnormal light chains and anemia would be expected.

The negative urinalysis excludes acute interstitial nephritis and glomerular disease.

In the absence of hypertension, severe bilateral renal arterial stenosis is unlikely.


A 35-year-old man with HIV infection diagnosed 2 months ago is evaluated because of fever and confusion for 1 day. He is on no medications.

On physical examination, he is afebrile, blood pressure is 110/70 mm Hg and pulse rate is 100/min. Other than confusion and bilateral lower extremity edema, the remainder of the examination is normal.


Hemoglobin – 7.8 g/dLLeukocyte count – 10,200/uLPlatelet count – 19,000/uLBUN – 37 mg/dLSerum creatinine – 2.7 mg/dL (1.0 mg/dL 2

months ago)Urinalysis – Specific gravity 1.030; 3+ hematuria,

trace proteinuria, trace ketonuria, no glucosuria. Urine microscopy is normal.

Peripheral blood smear shows many schistocytes.


Which of the following is the most likely cause of his renal failure?

(A) Acute tubular necrosis(B) HIV-associated nephropathy(C) Pyelonephritis(D) Thrombotic thrombocytopenic

purpura

AnswerAnswer


Answer: DThe course and laboratory findings are consistent

with thrombotic thrombocytopenic purpura, which can be a complication of HIV infection.

A case series from France suggest that thrombotic thrombocytopenic purpura is a common cause of acute renal failure in HIV infected patients.

Plasma exchange is indicated, but a recent case report suggests an important role for concurrent administration of antiretroviral therapy to achieve desired therapeutic outcomes.


Classic HIV-associated nephropathy is unlikely in the absence of significant proteinuria.

The urinalysis is incompatible with acute tubular necrosis or pyelonephritis.

None of these conditions are associated with a microangiopathic hemolytic anemia or thrombocytopenia.


A 70-year-old woman is evaluated because of malaise and anorexia for 1 week. She has hypertension treated with hydrochlorothiazide.

On physical examination, the supine blood pressure is 150/95 mm Hg, pulse rate is 80/min, respiration rate is 20/min, and temperature is 37.4 oC (99.3 oF). The blood pressure is 125/80 mm Hg and the pulse rate 96/min while standing. The remainder of the examination is unremarkable.


Hematocrit – 29%BUN – 62 mg/dLSerum creatinine – 4.6 mg/dLSerum sodium – 134 meq/LSerum postassium – 5.0 meq/LSerum chloride – 114 meq/LSerum bicarbonate – 15 meq/LSerum calcium – 12.5 mg/dLSerum inorganic phosphate – 8.5 mg/dLUrinalysis – Specific gravity 1.007; trace proteinuria;

no glycosuria or keonuria



(A) Hypercalcemia secondary to hydrochlorothiazide therapy

(B) Milk-alkali syndrome(C) Multiple myeloma(D) Primary hyperparathyroidism

AnswerAnswer


Answer: CThe decreased anion gap in the presence of anemia,

proteinuria, and hypercalcemia, and acute renal failure suggest multiple myeloma.

Acute renal failure is the initial presentation in as many as one half of patients with multiple myeloma.

Except in multiple myeloma, hypercalcemia in the presence of acute renal failure is relatively unusual because hyperphosphatemia and a decrease in renal 1-alpha hydroxylation of 25-hydroxycholecalciferol both act to predispose to hypocalcemia.


Hypercalcemia may cause renal insufficiency through several mechanisms, including hemodynamic effects of vasoconstriction that mediate renal sodium and water retention, and direct effects on renal tubular sodium and water handling, resulting in prerenal azotemia secondary to volume depletion.

The hypercalcemia that characterizes the milk-alkali syndrome is not associated with anemia or proteinuria and is usually associated with metabolic alkalosis.


Primary hyperparathyroidism should be associated with hypophsphatemia and not anemia or proteinuria.

Although hydrochlorothiazide toxicity can present with volume depletion and prerenal azotemia, the presence of hematologic and metabolic complications makes this less likely as a unifying diagnosis.


A 23-year-old previously healthy woman is evaluated in the office because of 4 days of fatigue, swelling of the feet and lower legs, and red-brown urine.

She takes no medications.On physical examination, her blood

pressure is 160/98 mm Hg, pulse is 92/min, respiration rate is 12/min, and temperature is 37.0 oC (98.6 oF).


The only positive findings on physical examination are her generally ill appearance, periorbital edema and pitting edema of the legs to just below the knee.

Laboratory testing reveals a serum creatinine of 3.8 mg/dL.

The urine dipstick examination is positive for blood.



(A) Acute glomerulonephritis(B) Acute interstitial nephritis(C) Acute pyelonephritis(D) Acute tubular necrosis

AnswerAnswer


Answer: AThe urinalysis shows a red blood cell cast.Casts are formed within the renal tubules and

are characteristically cylindrical with regular margins.

Red blood cell casts are red to brown in color and contain uniformly small, round red blood cells.

Red blood cell casts are found almost exclusively in the urine of patients with glomerulonephritis or vasculitis.


Acute interstitial nephritis or pyelonephritis can be associated with white blood cell casts.

Like red blood cell cats, leukocyte casts are cylindrical with smooth margins but they are composed of leukocytes rather than red blood cells.

Leukocytes are larger than red blood cells, are not red or brown in color, and have a granular appearance.


Acute tubular necrosis can be associated with muddy brown granular and epithelial casts.

These casts are pigmented and contain granules or tubular epithelial cells which are larger than leukocytes and contain a single, centrally located, large nucleus.

End of LectureEnd of Lecture

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acute renal failure darren dreyfus, d.o. associates in nephrology, p.c. st. vincent’s health...

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