GU Flashcards
What BUN/creatinine ratio is indicative of a prerenal azotemia?
> 20
How does Proteus mirabilis change urine pH?
Makes it more alkaline (e.g. 8). Uses urease to split urea into ammonia and carbon dioxide. Alkaline urine increases risk for struvite stones (magnesium ammonium phosphate)
How are simple renal cysts managed?
Reassurance only if asymptomatic, even if large
What shape are the crystals in cystinuria?
Hexagonal
What kind of stones does a urinary cyanide-nitroprusside test detect?
Detects elevated cystine levels - cystinuria crystals
What is treatment for uric acid stones?
Hydration, alkalization of the urine (e.g. potassium citrate), and a low-purine diet
What structural changes can be seen in the kidneys in pts with hypertension?
Benign nephrosclersis: Bilateral shrunken kidneys with damage to aterioles (nephrosclerosis) that progresses to damage to glomerular capillary tufts.
Nephrosclerosis: hypertrophy and intimal medial fibrosis.
Glomerulosclerosis: progressive loss of the glomerular capillary surface area with glomerular and peritubular fibrosis.
What insults can lead to minimal change disease in adults?
NSAIDS and lymphoma
What risk factors are associated with focal segmental glomerulosclerosis?
African American and Hispanic ethnicity, obesity, HIV, and heroin use
What are risk factors for membranous nephropathy?
Adenocarcinoma (e.g. breast, lung), NSAIDs, hep B, and SLE
What are risk factors for membranoproliferative glomerulonephritis?
Hep B and C
What is the timeline of crystal-induced acute kidney injury vs acute interstitial nephritis from medications?
Crystal-induced: <7 days after starting drug
AIN: 7-10 days after drug exposure
What medications/etiologies are associated with crystal-induced acute kidney injury?
Acyclovir, sulfonamides, MTX, ethylene glycol, protease inhibitors, and uric acid (tumor lysis syndrome)
What is Bartter’s syndrome?
A rare inherited defect in the thick ascending limb of the loop of Henle. It is characterized by low potassium levels (hypokalemia), increased blood pH (alkalosis), and normal to low blood pressure.
What are ways to prevent renal injury when using contrast?
Pre and post procedure hydration, N-acetylcysteine, and urine alkalization
What is the most common cause of acute epididymitis in a patient >35 yo?
Most often due to bladder outlet obstruction (e.g. BPH). Ascending coliform bacteria such as E. coli are most common pathogens
What is the most common cause of acute epididymitis in a patient <35 yo?
STI such as Chlamydia or gonorrhea
What are causes of type I renal tubular acidosis?
Lithium/Ampho B, analgesics, SLE, Sjogrens, sickle cell, hepatitis
How do you dx and tx type I renal tubular acidosis?
Urine pH > 5.4, HypoK, Kidney stones (due to problem with excreting H+ in distal tubules/collecting duct).
Tx with PO bicarb
What are causes of type II renal tubular acidosis?
Fanconi’s syndrome, multiple myeloma, amyloidosis, vitD def, autoimmune dz
How do you dx and tx type II renal tubular acidosis?
Due to problem reabsorbing bicarb in proximal tubule –> HypoK and osteomalacia.
Treat with potassium and mild diuretic (bicarb will not help)
What are causes of type IV renal tubular acidosis?
Due to hypoaldosteronism (also have high renin levels)- >50% caused by diabetes! Other causes include Addison’s, sickle cell, or any other cause of aldosterone def
How do you dx and tx type IV renal tubular acidosis?
Presents with hyperK, hyperCl, and high urinary sodium concentration even with salt restriction.
Treat with fludrocortisone
How is FENa calulated?
(urinary Na x serum creatinine)/(serum Na x urine creatinine)
What is the earliest renal abnormality in diabetic nephropathy?
Glomerular hyperfiltration
What dietary recommendations should be made to patients with recurrent renal calculi?
- Increase fluid intake
- Decrease sodium intake (decreasing sodium leads to increased calcium reabsorption from renal tubules)
- Normal dietary calcium intake
What is the mechanism behind membranoproliferative glomerulonephritis type 2 (dense deposit disease)?
IgG antibodies against C3 convertase of the alternative complement pathway which leads to persistent complement activation and kidney damage. Causes dense intramembranous deposits
What should you be thinking in a patient with worsening kidney function and flank pain after starting acyclovir?
Crystal-induced acute kidney injury (AKI)
What is hyposthenuria?
The inability of the kidneys to concentrate urine (results in very low specific gravity)
