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Nephrology > Azotemia > Flashcards

Azotemia Flashcards

1
Q

_____ is the p mary metric for kidney “function,” and its direct measurement involves administration of a radioactive isotope (such as inulin or iothalamate) that is filtered at the glomerulus into the urinary space but is neither reabsorbed nor secreted throughout the tubule.

A

GFR

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2
Q

In most clinical circumstances, direct GFR measurement is not feasible, and the plasma _____ level is used as a surrogate to estimate GFR.

A

creatinine

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3
Q

______ is the most widely used marker for GFR, which is related directly to urine creatinine (UCr ) excretion and inversely to PCr .

A

Plasma creatinine (P Cr)

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4
Q

Generally, patients do not develop symptomatic uremia until renal insufficiency is severe (GFR _____mL/min).

A

<15

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5
Q

_____has been proposed to be a more sensitive marker of early GFR decline than is PCr , with lesser effects of muscle mass on circulating levels;

A

Serum cystatin C

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6
Q

Radiographic evidence of _______can be seen only in chronic renal failure but is a very late finding, typically in patients with end-stage renal disease (ESRD) maintained on dialysis.

A

renal osteodystrophy

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7
Q

The ____ and _____ can facilitate distinguishing acute from chronic renal failure.

A

urinalysis
renal ultrasound

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8
Q

Patients with advanced chronic renal insufficiency often have some ______

A

proteinuria
nonconcentrated urine (isosthenuria; isosmotic with plasma)
small kidneys on ultrasound, characterized by increased echogenicity and cortical thinning.

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9
Q

GFR is maintained by prostaglandin-mediated dilatation of _____ arterioles and angiotensin II–mediated constriction of ___ arterioles.

A

afferent

efferent

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10
Q

Blockade of prostaglandin production by NSAIDs can result in severe ____ and ____

A

vasoconstriction
acute renal failure

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11
Q

Blocking a sin action with angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) decreases efferent arteriolar tone and in turn _____.

A

decreases glomerular capillary perfusion pressure

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12
Q

The ____ and _____can be useful in distinguishing prerenal azotemia from ATN

A

urinalysis

urinary electrolyte measurements

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13
Q

Urine Na of Prerenal vs Oliguric Acute Renal Failure

A

In prerenal conditions, the tubules are intact, leading to a concentrated urine (>500 mosmol), avid Na retention (urine Na concentration, <20 mmol/L; fractional excretion of Na [FE ], <1%), and U Cr /P Cr >40 (Table 52-2).

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14
Q

_____accounts for <5% of cases of acute renal failure but is usually reversible and must be ruled out early in the evaluation

A

Urinary tract obstruction

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15
Q

Obstruction is usually diagnosed by the presence of ureteral and renal pelvic ____ on renal ultrasound.

A

dilation

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16
Q

_____ account for ~90% of cases of acute intrinsic renal failure.

A

Ischemic and toxic ATN

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17
Q

_____ is observed most frequently in patients who have undergone major surgery, trauma, severe hypovolemia, overwhelming sepsis, or extensive burns.

A

Ischemic ATN

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18
Q

The kidney is vulnerable to toxic injury by virtue of its rich blood supply (____ of cardiac output) and its ability to concentrate and metabolize toxins.

A

25%

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19
Q

The finding of ____in interstitial nephritis has been reported but should prompt a search for glomerular diseases

A

RBC casts

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20
Q

The finding of RBC casts in the urine is an indication for early ____

A

renal biopsy

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21
Q

Oliguria refers to a 24-h urine output _____, and anuria is the complete absence of urine formation (______)

A

<400 mL

<100 mL

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22
Q

Nonoliguria refers to urine output _____ in patients with acute or chronic azotemia.

A

> 400 mL/d

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23
Q

The classic sediment finding in _____ is a predominance (>10%) of urinary eosinophils with Wright’s or Hansel’s stain; however, urinary eosinophils can be increased in several other causes of AKI, such that measurement of urine eosinophils has no diagnostic utility in renal disease.

A

allergic interstitial nephritis

24
Q

A patient presents with azotemia and ultrasound reveals bilateral small kidneys with thin cortices. Urinalysis shows bland sediment and proteinuria <3.5 g/24 h. What is the MOST likely diagnosis?
A. Acute tubular necrosis
B. Chronic renal failure
C. Acute interstitial nephritis
D. Glomerulonephritis

A

B

25
Q

A patient with azotemia and normal-sized kidneys undergoes urinalysis, which shows muddy brown casts and amorphous sediment with protein. What is the MOST likely diagnosis?
A. Acute tubular necrosis
B. Interstitial nephritis
C. Prerenal azotemia
D. Pyelonephritis

A

A

26
Q

A patient presents with azotemia and abnormal urinalysis showing white blood cells (WBCs), casts, and eosinophils. What is the MOST likely diagnosis?
A. Pyelonephritis
B. Renal artery occlusion
C. Acute interstitial nephritis
D. Glomerulonephritis

A
27
Q

A patient presents with azotemia and red blood cell (RBC) casts on urinalysis. What is the NEXT step to confirm the diagnosis?
A. Renal biopsy
B. Angiogram
C. Urine electrolytes
D. Urologic evaluation

A

A

28
Q

A patient presents with azotemia and oliguria. Urine studies reveal FeNa <1% and urine osmolality >500 mosmol. What is the MOST likely diagnosis?
A. Prerenal azotemia
B. Acute tubular necrosis
C. Chronic renal failure
D. Pyelonephritis

A

A

29
Q

A 45-year-old man presents with microscopic hematuria and proteinuria of 600 mg/24 hours. Urine microscopy reveals dysmorphic RBCs and RBC casts. What is the next step in the evaluation?

A) Urine culture
B) Renal biopsy
C) Hemoglobin electrophoresis
D) Intravenous pyelography (IVP)

A

B

30
Q

A patient with microscopic hematuria undergoes urine culture and eosinophil staining, both of which are positive. What is the most likely diagnosis?

A) Acute glomerulonephritis
B) Interstitial nephritis
C) Renal artery thrombosis
D) Renal mass

A

B

Positive urine eosinophils and pyuria strongly suggest interstitial nephritis, often associated with drug-induced allergic reactions or infections. This finding differentiates it from glomerulonephritis and vascular causes.

31
Q

The evaluation of proteinuria is shown schematically in Fig. 52-3 and typically is initiated after detection of proteinuria by ____

A

dipstick examination.

32
Q

This information is particularly important for the detection of _____ in the urine of patients with multiple myeloma.

A

Bence-Jones proteins

33
Q

Formal assessment of urinary protein excretion requires a _____

A

24-h urine protein collection (

34
Q

Smaller proteins (<20 kDa) are freely filtered but are readily reabsorbed by the _____.

A

proximal tubule

35
Q

Typically, healthy individuals excrete ____ of total protein and ____ of albumin.

A

<150 mg/d

<30 mg/d

36
Q

Another mechanism of proteinuria entails excessive production of an abnormal protein that exceeds the capacity of the tubule for reabsorption. This situation most commonly occurs with plasma cell dyscrasias, such as_____, that are associated with monoclonal production of immunoglobulin light chains.

A

multiple myeloma, amyloidosis, and lymphomas

37
Q

Dipstick examination (detects only albumin).
False Positives:
___

A

Alkaline urine (pH >7.0).
Highly concentrated urine.
Contamination with blood.

38
Q

Hematuria is defined as ________ and can be detected by dipstick.

A

two to five RBCs per high-power field (HPF)

39
Q
A
40
Q

_____ results from renal sodium retention and reduced plasma oncotic pressure, which favors fluid movement from capillaries to interstitium.

A

Edema

41
Q

_____ in nephrotic syndrome occurs through excessive urinary losses and increased proximal tubule catabolism of filtered albumin.

A

Hypoalbuminemia

42
Q

Isolated hematuria without proteinuria, other cells, or casts is often indicative of ____

A

bleeding from the urinary tract.

43
Q

Hematuria with dysmorphic RBCs, RBC casts, and protein excretion >500 mg/d is virtually diagnostic of _____

A

glomerulonephritis

44
Q

“sterile pyuria” with negative urinary bacterial cultures can be seen in _____

A

urogenital tuberculosis

45
Q

true polyuria

A

> 3 L/d

46
Q

The average person excretes between ____ mosmol of solutes per day, primarily as urea and electrolytes.

A

600 and 800

47
Q

This circumstance could arise from polydipsia, inadequate secretion of AVP (____ diabetes nsipidus), or failure of renal tubules to respond to AVP (____ diabetes insipidus).

A

central

nephrogenic

48
Q

______ with glucosuria is the most common cause of a solute diuresis, leading to volume depletion and serum hypertonicity.

A

Poorly controlled diabetes mellitus

49
Q

A _____ is recommended as the best method for distinguishing between central and nephrogenic diabetes insipidus.

A

plasma AVP level

50
Q

A _____ plus ______ may distinguish primary polydipsia from central and nephrogenic diabetes insipidus.

A

water deprivation test

exogenous AVP

50
Q

A 45-year-old woman presents with polyuria (>3 L/day) and low urine osmolality (<250 mosmol/L). Serum sodium is also low. What is the most likely diagnosis?

A) Solute diuresis
B) Central diabetes insipidus (DI)
C) Nephrogenic diabetes insipidus (DI)
D) Primary polydipsia

A

D

51
Q

A 60-year-old man presents with polyuria and urine osmolality >300 mosmol/L. Further history reveals recent high-protein feedings. What is the most likely mechanism of his polyuria?

A) Diabetes insipidus
B) Solute diuresis
C) Primary polydipsia
D) Acquired tubular disease

A

B

52
Q

A 50-year-old woman with a history of lithium therapy presents with polyuria and urine osmolality <250 mosmol/L. The water deprivation test shows no improvement in urine osmolality, even after ADH administration. What is the likely diagnosis?

A) Central diabetes insipidus
B) Nephrogenic diabetes insipidus
C) Primary polydipsia
D) Solute diuresis

A

B

In nephrogenic DI, the kidneys are insensitive to ADH, so urine osmolality does not increase after exogenous ADH administration. Lithium therapy is a common cause of acquired nephrogenic DI.

53
Q

A 55-year-old man is found to have proteinuria on routine dipstick testing. A 24-hour urinary protein excretion is 150 mg/day. Which condition is most likely responsible for this finding?

A) Diabetes mellitus
B) Minimal change disease
C) Essential hypertension
D) Nephrotic syndrome

A

C

54
Q

A patient presents with proteinuria of 4 g/day and generalized edema. What is the most likely diagnosis?

A) Myeloma-associated kidney disease
B) Focal segmental glomerulosclerosis (FSGS)
C) Intermittent proteinuria
D) Postural proteinuria

A

B

55
Q

A 45-year-old man presents with proteinuria of 3.2 g/day but no evidence of nephrotic syndrome. Which of the following is the most likely diagnosis?

A) Minimal change disease
B) Postural proteinuria
C) Myeloma-associated kidney disease
D) Intermittent proteinuria

A

C

Nephrology (3 decks)

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