7/21/16 Flashcards
nephrotic syndromes associated with NSAIDs
minimal change disease and membranous nephropathy
tx for severe, symptomatic SIADH vs chronic SIADH
severe symptomatic: tolvaptan, conivaptan (ADH receptor antagonists)
chronic: demeclocycline (blocks action of ADH at collecting duct)
what happens if hyponatremia is corrected too quickly? hypernatremia?
hyponatremia corrected too quickly = central pontine myelinolysis/osmotic demyelinizaiton
hypernatremia corrected too quickly = cerebral edema
do ACE inhibitors cause hyper- or hypokalemia?
hyperkalemia (aldosterone decrease)
does acidosis cause hypo- or hyperkalemia and why?
acidosis causes hyperkalemia because cells will pick up hydrogen ions and release potassium ions in exchange
what three cardiovascular drugs cause hyperkalemia and how?
DIGOXIN and BETA BLOCKERS inhibit the sodium/potassium ATPase that normally brings potassium into the cells.
HEPARIN causes increased tissue release
tx for hyperkalemia causing EKG changes
calcium chloride or calcium gluconate (protects the heart, does not lower the potassium level), then sodium bicarbonate (alkalosis drives potassium into cells) and glucose with insulin
what should you consider when hypokalemia is not improving with normal supplementation?
hypomagnesemia can lead to increased urinary loss of potassium. there are magnesium-dependent potassium channels; when magnesium is low, they open and spill potassium into the urine. if magnesium is replaced, it will close up these channels and stop urinary loss.
two most important causes of metabolic acidosis with normal anion gap
renal tubular acidosis and diarrhea (normal anion gap because chloride levels rise. also referred to as hyperchloremic metabolic acidosis. anion gap increases with ingested substances or organic acids that are anionic and drive down the chloride level)
pathogenesis of distal (type I) RTA
distal tubule is responsible for generating new bicarbonate. drugs like amphotericin and autoimmune diseases damage the distal tubule. if new bicarbonate cannot be generated at the distal tubule, then acid cannot be excreted into the tubule. end result is ALKALINE URINE, which causes increased formation of calcium oxalate KIDNEY STONES.
pathogenesis of proximal (type II) RTA
normally 85-90% of filtered bicarbonate is reabsorbed at the proximal tubule. damage to the proximal tubules decreases the ability of the kidney to reabsorb bicarbonate. the end result is bicarbonate loss in the urine (ALKALINE URINE) until bicarbonate becomes so depleted that distal tubule absorbs the rest and no more bicarbonate is left to get into urine (ACIDIC URINE)
tx for proximal (type II) RTA
thiazide diuretics cause volume depletion. volume depletion will enhance bicarbonate reabsorption.
pathogenesis of type IV RTA
occurs most often in diabetes. decreased amount or effect of aldosterone at the kidney tubule, which leads to loss of sodium and retention of potassium and hydrogen ions. end result is a HIGH URINE SODIUM despite a sodium-depleted diet and NORMAL URINE PH.
most important distinction between type IV vs type I and type II RTA
type IV RTA causes HYPERKALEMIA whereas type I and type II have HYPOKALEMIA (potassium is lost in the urine)
tx for type IV RTA
fludrocortisone (steroid with the highest mineralocorticoid or “aldosteronelike” effect
what is the best way to distinguish between diarrhea and RTA when someone has non-anion gap metabolic acidosis?
urine anion gap (sodium minus chloride). positive in RTA (less chloride in urine because less acid in urine), negative in diarrhea (kidneys are still able to excrete acid and therefore chloride. diarrhea causes metabolic acidosis so kidneys try to compensate by excreting more acid)
what are the signs of ethylene glycol overdose? tx?
found in antifreeze (de-icing for windshields). anion gap metabolic acidosis, oxalic acid cystals on UA. tx is fomepizole
sx and tx of methanol overdose
sx: inflamed retina, anion gap metabolic acidosis
tx: fomepizole
tx of salicylate overdose
aspirin overdose (anion gap metabolic acidosis) is treated with urine alkalinization
3 major causes of metabolic alkalosis
vomiting, loop/thiazide diuretics, increased aldosterone
relationship between Crohn disease and kidney stones
Crohn disease causes kidney stones because of increased oxalate absorption
what are is the tx for kidney stones 5-7mm? 7mm-2cm?
5-7mm: nifedipine and tamsulosin to help them pass
7mm-2cm: lithotripsy
relationship between metabolic acidosis and calcium
chronic metabolic acidosis leaches calcium out of bones and they become soft (osteomalacia). it also increases stone formation by increasing calcium in circulation and decreasing citrate (citrate normally binds calcium, making it unavailable for stone formation)
best initial therapy for HTN in pts with coronary artery disease
beta blockers, ACE, ARB