Renal & Electrolytes Flashcards
(51 cards)
Treatment of patients with severe hypovolemic hypernatremia
1st correct the hypovolemia with 0.9% saline.
Then switch to 0.45% saline + 5% dextrose to correct the hypernatremia no faster than 1mEq/L/hour
Earliest renal abnormality in patients with diabetes? Earliest observable abnormality in these patients?
Earliest abnormality = glomerular hyperfiltration
Earliest observable abnormality = GBM thickening
Imaging modalities of choice for patients with suspected kidney stones
Non contrast helical CT and ultrasound (preferred if alternate dx is unlikely or pregnant)
Treatment of choice for uric acid stones
Alkalinization of the urine to a pH of 6 to 6.5 with potassium citrate.
Stones not observable on imaging
Calcium stones
Most common type of nephrotic syndrome where you see renal vein thrombosis?
Membranous glomerulopathy
Differentiating benign renal cysts from malignant renal cysts
Simple: smooth, homogenous, do not enhance with contrast, asymptomatic and unilocular.
Malignant: thick, irregular walls, loculated, heterogenous, enhance with contrast, cause pain/hematuria/HTN
Most common causes of anion gap metabolic acidosis
Methanol Uremia DKA Propylene glycol INH Lactic acid Ethylene glycol Salicylates
Appropriate rate of correction of serum sodium for patients with hyponatremia
No more than 0.5mEq/dL/hr and not exceeding 12mEq in 24 hours.
How to calculate serum osmolarity
2Na + BUN/2.8 + Glc/18
Calculate serum osmolar gap
Measured Sosm - Calculated Sosm. This is typically done when you suspect ethanol, methanol or ethylene glycol toxicity.
Diagnostic criteria for SIADH
Sosm Sosm
Una > 20
Absence of hypovolemia
Normal renal, adrenal and thyroid function
No obvious stimulus to activate the neuroendocrine hormonal response that increases ADH secretion
Absence of other known causes of hyponatremia
Why is metabolic acidosis due to renal disease rarely seen in patients with an eGFR > 20?
The remaining nephrons compensate greatly for decreased H+ secretion by increasing NH3 production that gets secreted in the urine as NH4 to get rid of the H+.
Dietary recommendations for patients with renal calculi?
Increased fluid to >2L urine/day, decreased Na+ to
Definitive measures used to reduce serum K+
Cation exchange resins like sodium polystyrene sulfonate
How to confirm the diagnosis of cystinuria in a patient with stones?
Hexagonal crystals and urinary cyanide nitroprusside test showing elevated cystine levels.
Post-void residual volume that is significant for bladder outlet obstruction
> 50 mL
Complete vs. partial DI
Complete: urine osmolarity is > 600
Partial: urine osmolarity is 300-600
Common causes of nephrogenic DI
Hypercalcemia, hypokalemia, tubulointerstitial renal disease, Li, demeclocycline, foscarnet, cidofovir and amphotericin
Why do saline-resistant causes of metabolic alkalosis have a high urine Cl- concentration?
Excess mineralocorticoid stimulation results in excess serum Na+ and volume retention. The kidneys respond by secreting more Na+ and Cl-, resulting in increased Cl- concentration.
Treatment of UTIs and pyelonephritis in non-pregnant women?
Acute uncomplicated cystitis: nitrofurantoin x 5 days (avoid if GFR 20%). Fosfomycin x1. Culture urine only if treatment fails.
Complicated cystitis: fluoroquinolones 5-14 days. Amp-gent for more severe cases. Culture urine to confirm correct antibiotic choice.
Pyelo: fluoroquinolones as outpatient therapy. IV fluoroquinolones or aminoglycoside +/- ampicillin for inpatient therapy. Culture urine to confirm correct antibiotic choice.
What constitutes a case of complicated cystitis?
DM, CKD, pregnancy, immunocompromised, urinary tract obstruction, hospital-acquired infection, procedure-associated infection or catheter-associated infection.
Management of hypercalcemia?
Severe (sx or Ca > 14): NS at 200mL/hr with goal urine output of 100-150mL/hr + calcitonin immediately. Give bisphosphonates for long-term treatment.
Moderate (Ca 12-14): no treatment
Mild (Ca
Tests to get in patients with BPH
Urinalysis and PSA if life expectancy is > 10 years
