Nephrology Flashcards
orthostatic proteinuria - definition
increase in urinary protein excretion in upright position; in supine position, urinary protein excretion < 50 mg/8 hr; total urine protein excretion is usually still less than 1 g/24 hr
what type of casts are associated with acute intersitital nephritis?
leukocyte (WBC) casts
sterile pyuria - no culture
MC etiology of AIN
drugs - particularly, B-lactam antibiotics
characteristic triad of AIN
rash, fever, eosinophillia in a setting of renal insufficiency
types of cases seen in ATN?
muddy brown casts
what is persistent hematuria?
presence of > 3 RBCs/hpf on two or more samples
next step in diagnosing persistent hematuria?
cystoscopy or kidney USG - to evaluate for genitourinary malignancy
characteristics of nonglomerular hematuria
normal appearing RBCs on urine microscopy and absence of erythrocyte casts and protein
RF for genitourinary malignancy
male sex
age > 50
tobacco use
drugs - cyclophosphamide, benzene, radiation
what is first step in diagnosis of urinary obstruction?
kidney ultrasound
first step in management of urinary obstruction?
insertion of foley catheter
triad of hemolytic uremic syndrome
acute kidney injury
thrombocytopenia
microangiopathic hemolytic anemia - schistocytes
MCC of HUS
infection by shiga-toxin producing E.coli
familial deficiency of factor H
what should you consider if a patient presents with hypotension, hyponatremia, decreased urine sodium excretion and bland urine sediment
pre-renal azotemia
therapy for hepatorenal syndrome (ascites, portal HTN)
midodrine and octreotide
characteristic findings in tumor lysis syndrome
hyperkalemia
hyperphosphatemia
hyperuricemia
Tx. of tumor lysis syndrome
rasburicase
what is the Tx. strategy in pts with diabetic nephropathy
angiotenson receptor blocker or ACE inhibitor to reduce blood pressure < 130/80 or < 125/75 if significant proteinuria is present
what change in lab findings can you expect in a pt taking ACEi/ARBs
increase in creatinine - up to 30% is acceptable
should you combine ACEi and ARBs in the tx. of diabetic nephropathy?
no - recent trials showed no benefit in morbidity or mortality and it increased the adverse effects compared to ACEi alone
absolute indications for dialysis
uncontrollable hyperkalemia uncontrollable hypervolemia altered mental status/somnolence pericarditis bleeding diathesis
relative indications for dialysis
NV, decreased appetite severe metabolic acidosis mild changes in mental status - lethargy asterixis worsened kidney function with GFR < 15
what is recommended in pts with DM who have features of non-diabetic kidney disease?
kidney biopsy
what type of bone disease is associated with chronic kidney disease
secondary hyperparathyroidism
- hyperphosphatemia
- hypocalcemia
- elevated serum PTH and ALP
what kind of bone disease is associated with hypoparathyroidism caused by excess vit D intake and/or oral calcium loading; manifests as bone pain with serum PTH < 100
adynamic bone disease
urine anion gap
(U-Na + U-K) - U-Cl
- normally between 30-50 mmol/L
metabolic acidosis of extrarenal origin is suggested by..
large, negative urine anion gap
metabolic acidosis of kidney origin is suggested by..
positive urine anion gap
how do you predict the increase in serum HCO3- that should occur with respiratory acidosis?
- 1 mmol/L HCO3- for every 10 mmHg increase in PCO2 (in acute situations)
- 4 mmol/L for every 10 mmHg PaCO2 (chronic)
how can you calculate the expected decline in HCO3- to compensate for respiratory alkalosis ?
for every 10 mmHg decline in PaCO2, the expected decline in HCO3- is 2 mmol/L
causes of respiratory alkalosis
psychogenic - hyperventilation normal pregnancy pulmonary vascular dz - HTN, PE pulmonary parenchymal dz - pneumonia, fibrosis cirrhosis heart failure sepsis
how do you distinguish metabolic acidosis due to ethylene glycol poisoning vs. DKA, alcoholic ketoacidosis or lactic acidosis?
ethylene glycol (and methanol) will have an INCREASED osmolar gap - calculate!
formula for osmolar gap
2(Na) + BUN/2.8 + glucose/18
how do you calculate what the expected PaCO2 should be if compensating for a metabolic alkalosis?
PaCO2 should be increasing atleast 0.7 mmHg for every 1 mmol/L increase in HCO3
normal plasma osmolarity
275-295 mOsm/Kg
diuretic induced hyponatremia MC after what drugs?
thiazide diuretics
Tx. of diuretic induced hyponatremia
stopping diuretics and infusing NS for mildly sx. pts or 3% saline for significantly sx. pts
electrolyte abnormalities commonly associated w/ acetazolamide
hypokalemia
metabolic acidosis - impairs HCO3- reabsorption
what ECG findings indicate hyperkalemic cardiotoxicity?
spiked T waves
widened QRS complexes
first step in tx. urgent hyperkalemia
IV calcium gluconate - takes 2-3 mins to work
second step in tx. urgent hyperkalemia
intracellular shift with any of the following:
- sodium bicarbonate
- albuterol
- glucose + insulin
what does a urine K+ conc. < 20 mean?
extra-renal losses i.e. GI tract or skin
what two GI disorders lead to potassium loss?
diarrhea (laxative abuse)
villous adenoma
how can you tell apart diuretic abuse from laxative abuse?
diuretic abuse = hypokalemia, metabolic alkalosis and high U-K+ conc
laxative abuse - hypokalemia with metabolic acidosis and low U-K+ conc
effect of acute pancreatitis on calcium levels
acute pancreatitis can generate free fatty acids that avidly chelate insoluble calcium salts in pancreatic bed, leading to HYPOCALCEMIA
how do you tx. hypercalcemia in the setting of sarcoidosis?
prednisone - decreased vit D3 production by decreasing the number of activated macrophages
what electrolyte abnormality can present with severe muscle weakness in an alcoholic pt?
hypophosphatemia - initially levels may look normal, but upon administration of IV glucose, it shifts phosphate into cells resulting in severe hypophosphatemia
