2: Hematuria Flashcards
Does red urine = blood in urine?
Spin it down: if sediment is red = hematuria, if supernatant is red, it is not hematuria (need to dipstick for heme)
Does painless hematuria narrow DDx?
Absolutely. UTIs and stones generally symptomatic. Cancer may be painless.
WIS lack of proteinuria with hematuria?
No proteinuria = unlikely to be a glomerular issue (it is extraglomerular)
Frequent causes of hematuria (4)
Transient/unexplained, UTI, stones, cancer (bladder, kidney, prostate)
Less frequent causes of hematuria (6)
Exercise, trauma, endometriosis, sickle cell, PCKD, glomerular disease
Risk factors for urinary tract malignancy
> 35 years of age, smoking, occ exposure (benzene, aromatic amines), history of: gross hematuria, chronic cystitis, pelvic radiation, cyclophosphamide, chronic indwelling FB, analgesic abuse, obesity, HTN. EtOH may be protective.
Causes of red supernatant dipstick negative for heme (3)
porphyria, phenazopyridine, beets
Red supernatant dipstick positive for heme ddx
myoglobinuria (plasma clear) or hemoglobinuria (plasma is red)
What does urine dipstick test for?
proteinuria or hematuria
What might cause a false negative urine dipstick test?
presence of formalin or high [ascorbic acid]
Cause of urine dipstick false positive
pH > 9 or contamination w oxidizing agents used to clean perineum
What constitutes hematuria in children and adults?
RBC/high power field: 5 in children or 2 in adults
What UA findings point to glomerular (4) vs extraglomerular (1) source of hematuria?
Glomerular: red cell casts, proteinuria, dysmorphic RBCs, smokey brown or coca-cola color
Extraglomerular: clots (possible papillary necrosis)
How is angiography used with hematuria?
Investigate bleeding not defined by CT, can occlude causative blood vessels
What percent of hematuria is due to glomerular disease? How is this diagnosed?
50%, kidney biopsy
Unusual causes of hematuria
Arterio-venous malformations, fistulas, loin pain - hematuria syndrome
What is loin pain - hematuria syndrome
Abnl GBM + assoc w/ intratubular crystal formation. usually presents with flank pain w/o infection or obstruction
What is Nutcracker syndrome? What population is it most frequently found in?
Asian children. Left renal vein compression by aorta and superior mesenteric artery.
Evaluating microscopic hematuria in an asymptomatic child. What’s next?
Determine presence of protein. None: benign/ observe. Present: quantify w 1st void morning spec. Total protein/creat ratio (nl <0.3) refer if above
What percent of men and women develop a symptomatic stone by age 70?
12% of men and 5% of women, rate increases with age
What % of stones are calcium? What are they usually precipitated with?
80%. Oxalate > phosphate.
What type of stones are known as infection stones?
Struvite
Which stones are caused by a genetic abnormality? What is the defect and pattern of inheritance?
Cysteine. Autosomal recessive impairment of cystine transport -> dec prox tubular reabs
Presentation of pain with stone
flank, abdominal, testicular or labial, tends to wax and wane. May have assoc n/v, dysuria, urgency, hematuria
What causes the pain associated with a stone?
Dilation of ureter behind stone due to back up.
What type of stones can be visualized on XR (KUB)?
Calcium= most radiopaque. Cystine visible but less opaque (discrete or staghorn)
What imaging technique is generally used for a patient with known hx stone?
US
What medications are helpful with stones?
Alpha blocker (tamsulosin) or Ca channel blocker (nifedipine) relaxes ureteral muscles allowing the stone to pass more easily
When does a pt with a stone require hospitalization?
When unable to maintain hydration and urine output, need IV fluids.
What shape are calcium oxalate crystals?
Monohydrate: dumbbell, needle
Dihydrate: envelope
What is the effect of citrate excretion on stone formation?
Citrate inhibits stone formation
What are the 3 types of hypercalciuria?
- Absorptive: autosomal dom -> inc Calcitrol 2. Fasting (resorptive): bone loss 3. renal: defective Ca reabsorp in prox tubule
Sources of hypocitraturia
Almost anything that gives you a metabolic acidosis. Chronic diarrhea, renal tubular acidosis, high protein diet, Topiramate (anti-seizure med). Ureteral diversion (surgical)
Sources of excreted oxalate
Glycine metabolism (40%), ascorbic acid metab (40%), diet (10%)
How do oxalate and calcium interact in the intestine?
Bind each other. If Ca is decreased or complexed with fatty acids/bile acids -> more free oxalate -> absorbed
What is medullary sponge kidney?
Abnormal medullary papilla -> reflux of filtrate -> risk for crystallization
How does salt affect Ca level?
Dec salt -> inc % reabsorption of Na -> Ca follows (less excreted = less likely to form stones)
If someone gets a Ca stone, should they reduce their Ca intake?
No. Dec Ca -> more oxalate absorbed from GI tract -> more stones.
Mech of thiazides in reducing stone formation
Dec Ca excretion in urine, used esp for absorptive hypercalciuria
Potassium citrate and bicarbonate mech of reducing stone formation
For pts w Ca-oxalate stones, alkalinizes urine reducing formation
Orthophosphate MOA w regard to stone formation
reduces Ca in urine
Febuxostat MOA
Decreases uric acid prod by inhibiting xanthine oxidase (as does allopurinol)
Calcium carbonate MOA
binds oxalate in stomach preventing absorption
What % of stones in US are uric acid? When are these more frequent?
5-10% though they make up 40% of stones in hot arid climates (low urine volume and acidic)
Typical serum uric acid level for someone forming a uric acid stone
Normal serum level
Prevention options for uric acid stones (3)
Urine output >2L/d
Alkalinization of urine (req 3-4 doses/d)
Allopurinol/Febuxostat (easiest, just 1x/d)
What type of crystals form only in alkaline urine? What shape?
Struvite, coffin lid shaped.
Struvite stone composition
magnesium ammonium phosphate
What are the 2 requirement for struvite stone formation? When are these conditions met most commonly?
Inc ammonia prod and inc urine pH. Satisfied by urease pos UTI (proteus or klebsiella)
How does increased urine pH facilitate struvite stone formation?
Decreases solubility of phosphate
What drug acts as a urease inhibitor?
Acetohexemic acid
Why might a patient prone to urease pos UTI with a chronic indwelling catheter be given chronic abx?
Goal: get rid of urease-producing organisms but not others, allowing the less harmful ones to colonize
Shape of cystine crystals?
Hexagonal, essentially pathognomonic for cystinuria.
Cystinuria subtypes
Based on parents cystine excretion, can be combo
I/I: normal, II/II: large, III/III: intermediate
Rec fluid intake for cystine stone formers?
3L/day
Med therapy for cystine stone formers
Alk of urine, dec Na intake -> inc prox tub cystine reabs. Chelators: Penicillamine, Tiopronin, Captopril
In what type of stone is ESWL less effective? Why?
Cystine, a softer stone
Rate of stone recurrence over 10 years
50%, men > women
What percent of pts require intervention vs pass stones spontaneously?
50/50
ESWL complications
Obstruction by broken off chunks, reversible damage to blood vessels and tubules depending on # and energy of shocks, new HTN (renin release?)
Long term ESWL complication
impairment of renal fx, prob from scar formation. Changes present at 4 years.
Which stones have a particularly high incidence of stone formation from residual calculi after ESWL?
Struvite
Do residual stone particles after ESWL matter?
Yes, nidus for further formation
