kidney stones Flashcards
complications of kidney stones
hydronephrosis and pyelonephritis. presents with unilateral flank pain, colicky pain radiating to groin, hematuria.
calcium stones: when do they precipitate? x ray findings? urine crystal? notes
incr. pH: calcium phosphate stones precipitate
decr. pH: calcium oxalate stones precipitate.
radiopaque.
envelope/dumbell crystals.
promoted by hypercalciuria (idiopathich, cancer, incr. PTH). oxalate crystals can result from ethylene glycol, vitamin C abuse, or Crohn disease.
tx: thiazides, citrate.
most common kidney stone presentation: calcium oxalate stone in a pt with hypercalciuria and normocalcemia
ammonium magnesium phostphate kidney stones: when do they precipitate? x ray findings? urine crystal? notes
precepitates at high urine pH. radiopaque. coffin lid.
aka struvite. caused by infection by urease positve bugs (proteus mirabilis, staphylococcus, klebsiella) that hydrolyze urea to ammonia –> urine alkalinization. can form staghorn caliculi that may be nidus for UTIs.
tx: remove underlying infection; surgery
uric acid kidney stones when do they precipitate? x ray findings? urine crystal? notes
precipitate at low pH. rediolucent. rhomboid or rosetes. risks: decr. urine vol, arid climates, acidic pH. visible on CT and ultrasound but not x-ray. assoicationg with hyperuricemia (ie gout). often seen in diseases with incr. cell turnover like leukemia, myeloproliferative disorders.
alkalize the urine as tx
cystine kidney stones: when do they precipitate? x ray findings? urine crystal? notes
low pH. radiopaque. hexagonal. mostly seen in kids secondary to cystinuria. can form staghorn caliculi. sodium nitroprusside test positive. tx: alkalization, hydration
chronic renal failure: common cuases, manifestations
causes: DM, HTN, glomerular disease (other causes possible, these are just the top 3)
features:
1. uremia: nausea, anorexia, pericarditis, platelet dyfunction (inhbits aggregation and adhesion),ecephalopathy with asterixis, deopsition of urea crystals in the skin.
2. salt and water retention with HTN
3. hyperkalemia with metabolic acidosis
4. anemia d/t decr. EPO production by renal peritubular interstitial cells.
5. hypocalcemia from decr. 1-alpha hydroxylation of vitamin D by renal proximal tubular cells. hyperphosphatemia.
6. osteodystrophy from secondary hyperparathyroidism, osteomalacia, and osteoporosis.
(MAD HUNGER: metabolic acidosis, dyslipidemia (incr. TGs), hyperkalemia, uremia, Na/H2O retention, growth retardation and devo delay in kids, EPO failure, renal osteodystrophy)
cystitis causative agents
e coli (gram neg rod, lactose fermenter), s. saprophyticus (gram pos catalase pos, coagulase negative, novobiocin resistant), klebsiella pneumoniae (gram neg rod, lactose fermenter), proteas mirabilis (gram neg rod, lactose non-fermenter, oxidase negative), E faecalis (gram pos, catalase negative, grows in bile and 6.5% NaCl), adenovirus (hemorrhagic cystitis)
sterile pyuria
pyuria (> 10WBC/HPF) with a negative urine culture. suggests urethritis from chlamydia trachomatis or N. gonorrheae
most common causes of pyelonephritis
e coli (90%), e. faecalis, klebsiella
chronic pyelonephritis
interstitial fibrosis and atrophy of tubules due to multiple bouts of acute pyelonephritis. due to vesicoureteral reflex (kids) or obstruction (BPH, cervical CA).
leads to cortical scarring with blunted calyces. scarring at upper and lower poles is characteristic of the vesiculoreteral reflux.
atrophic tubules containing eosinophilic proteinaceous material resemble thyroid follicles. waxy casts may be seen in urine
renal osteodystrophy
damage to bone d/t renal failure:
1. osteitis fibrosa cystica: hypocalcemia. PHT rises, and calcium is resorbed from bone –> fibrosis and cyst formation.
2. osteomalacia: can’t mineralize the osteoid made by osteoblasts.
3. osteoporosis: leech calcium to buffer the metabolic acidosis.
underlying cause:
failure of vitamin D alpha hydroxylation by the renal proximal tubular cells –> hypocalcemia, hyperphosphatemia, secondary hyperparathyroidism. hyperphosphatemia also independently increases serum Ca by causing tissue calcifications, whereas low 1,25 (OH) vitamin D causes decr. interstitial calcium absorption. subperiosteal thinning of bones.
diffuse cortical necrosis
acute generalized cortical infarction of both kidneys, likely due to a combination of vasospasm and DIC. associated with obstetric catastrophes (abruptio placentae) and septic shock.
cystitis
infection of the bladder that presents as dysuria, urinary freq, urgency, and suprapubic pain. systmeic signs (fever) are usually absent.
labs: cloudy urine with >10 WBCs/HPF
positive leukocyte esterase and nitrites (for gram neg organisms). culture: >100,000 colony forming units.`
risk of dialysis; changes to the kidney
shrunken kidneys with cysts and incr. risk of renal cell carcinoma
