Renal Pathology

Question 1

What is the likely diagnosis for a patient with a history of tophaceous gout who experiences flank pain and hematuria with no noted radiographic abnormalities?

Answer 1

Uric acid stones, which are not visible on x-ray films (radiolUcent); may be minimally visualized with either CT or ultrasound

Question 2

A child presents with edema. Urinalysis is positive for 3+ protein. Further evaluation reveals gonadal dysgenesis and a renal mass. What genetic abnormality is likely present?

Answer 2

Loss-of-function mutation in the WT1 tumor suppressor gene (chromosome 11), which is found in Denys-Drash syndrome

Question 3

What 2 conditions commonly lead to chronic pyelonephritis because they predispose individuals to infection?

Answer 3

Vesicoureteral reflux, chronic obstruction by kidney stones

Question 4

What are the 4 most common renal stones, in descending order of prevalence

Answer 4

Calcium (80%, especially calcium oxalate), ammonium magnesium phosphate (15%), uric acid (5%), and cystine

Question 5

In a patient with a urine osmolality < 350, Na+ > 40, FENa > 2%, BUN/Cr > 15, and postvoid residual urine of 125 mL, what type of acute kidney injury is the likely cause?

Answer 5

Postrenal azotemia (the key is the postvoid residual value which should be near zero normally)

Question 6

How does the glomerular filtration rate (GFR) change in a patient with intrinsic renal failure?

Answer 6

GFR decreases as a result of fluid backflow caused by obstructing necrotic debris in the tubules from acute tubular necrosis (patchy necrosis)

Question 7

What are 3 possible treatments for stress incontinence?

Answer 7

Weight loss, Kegel exercises to strengthen pelvic floor muscles, pessaries

Question 8

Which type of nephrotic syndrome may be caused by antibodies to phospholipase A2 receptors?

Answer 8

Primary membranous nephropathy

Question 9

What are the 2 characteristic findings of focal segmental glomerulosclerosis on light microscopy?

Answer 9

Segmental sclerosis and hyalinosis of glomeruli

Question 10

What are 8 key clinical consequences of renal failure?

Answer 10

Metabolic Acidosis, Dyslipidemia (↑TG), Hyperkalemia, Uremia, Na+/H2O retention, Growth retardation/developmental delay, EPO deficiency, Renal osteodystrophy (MAD HUNGER)

Question 11

An otherwise healthy 36-year-old woman presents with resistant hypertension and a bruit over the right flank. Where would you expect to see stenosis on angiography?

Answer 11

Within the distal two-thirds or segmental branches of the right renal artery, a classic presentation of renal artery stenosis due to fibromuscular dysplasia

Question 12

Obstetric catastrophes (eg, placental abruption) and septic shock are both associated with which serious renal pathology?

Answer 12

Diffuse cortical necrosis

Question 13

What is the most common treatment for a suspected renal oncocytoma?

Answer 13

Surgical resection (to rule out a true malignancy, especially renal cell carcinoma)

Question 14

What finding on urinalysis distinguishes gram-negative bacteria from gram-positive bacteria?

Answer 14

The presence of nitrites indicates the presence of gram-negative bacteria (ie, Enterobacteriaceae)

Question 15

What action is most useful in both treating and preventing kidney stones?

Answer 15

Fluid intake (adequate hydration)

Question 16

In a patient with uric acid kidney stones, what are 2 treatment options?

Answer 16

Allopurinol and urine alkalinization

Question 17

What are the typical responses of primary minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), and membranous nephropathy to steroid therapy?

Answer 17

Primary (idiopathic) MCD has an excellent response, FSGS has an inconsistent response, and membranous nephropathy has a poor response

Question 18

What are the 2 most common treatment options for acute simple cystitis?

Answer 18

Trimethoprim-sulfamethoxazole (TMP-SMX), nitrofurantoin

Question 19

A patient with sepsis becomes hypotensive and develops progressive oliguria. Urinalysis shows muddy brown casts. What is the likely cause of this renal pathology?

Answer 19

Decreased renal blood flow, causing ischemic damage to tubular cells (ischemic acute tubular necrosis)

Question 20

Diffuse cortical necrosis is thought to be related to a combination of which 2 pathologic processes?

Answer 20

Disseminated intravascular coagulation and vasospasm

Question 21

What immunofluorescence findings are typically associated with focal segmental glomerulosclerosis?

Answer 21

Immunofluorescence is often negative, although it may be positive for nonspecific focal deposits of IgM, C3, C1

Question 22

In a patient with intrinsic renal failure, what is the expected urine osmolality, urine Na+, fractional excretion of sodium (FENa), and blood urea nitrogen/creatinine (BUN/Cr) ratio?

Answer 22

Urine osmolality < 350 mOsm/kg, urine Na+ > 40 mEq/L (i.e., failure to concentrate urine); FENa > 2%, BUN/Cr ratio < 15 (i.e., failure to reabsorb)

Question 23

What is the blood urea nitrogen/creatinine ratio in a patient with intrinsic renal failure? Why?

Answer 23

< 15; Kidneys are not able to reabsorb urea so it remains in the urine leading to a reduced blood urea nitrogen to creatinine ratio

Question 24

A patient receiving long-term hemodialysis has multiple anechoic cortical/medullary cysts detected by bilateral renal ultrasonography. What 2 mutations may cause this disease?

Answer 24

Mutations in PKD1 (chromosome 16, ~85% of cases) or PKD2 (chromosome 4, ~15% of cases) can cause autosomal dominant polycystic kidney disease

Question 25

What chemotherapeutic agent is known to dramatically increase the risk for transitional cell carcinoma of the bladder?

Answer 25

Cyclophosphamide (may also cause hemorrhagic cystitis)

Question 26

What are the 2 ways that hypocalcemia occurs in patients with renal osteodystrophy?

Answer 26

High serum phosphate binds calcium resulting in tissue deposits, and decreased 1,25-(OH)2D3 impairs intestinal calcium absorption

Question 27

In a patient with prerenal azotemia, what is the expected urine osmolality, urine Na+, fractional excretion of sodium (FENa), and blood urea nitrogen/creatinine (BUN/Cr) ratio?

Answer 27

Urine osmolality > 500 mOsm/kg, urine Na+ < 20 mEq/L (i.e., concentrated urine); FENa < 1%, BUN/Cr ratio > 20 (i.e., increased reabsorption)