Crystalluria
Measurement of the glomerular filtration rate
Method
Urea
Plasma creatinine Creatinine clearance
Cystatin C
51Cr-EDTA
Comments
Poor surrogate
variable production ratevariable excretion rate
Better than urea
Poor discrimination at near-normal GFR
Reasonable surrogate but depends on accurate timed urine collection (uaually 24 hours)
In patients with DM. Expensive
The best surrogate in clinical practice
Expensive
Near perfect measurement of GFR but
needs continuous infusion
Inulin clearance difficult urine and plasma assays
research studies only – not suited to clinical practice
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Markers of renal functional state
•Serum creatinin
•Glomerular filtration rate (creatinin clearance– depuration of N volume of blood in a unit of, ml/min)
Creatinin clearance (90-140 ml/min/l.73 m2)
•Creatinin is filtered in glomeruli and only 10-15% is secreted by tubuli
•Clinical usefulness
–Assessment of kidney function in case of kidney failure
–Monitoring in case of treatment with nephrotoxic drugs
–Calculation of drug doses when they are excreted with urine
Creatinin clearance
(проба Реберга-Тареева)
CrCl = (Uv)х(Ucr) / (SCr)х(1440) x 1.73 m2/ ППТ
Uv = 24 h urine volume
Ucr = creatinin concentration in urine SCr = serum creatinin concentration 1440 – minutes in 24 h
ППТ – body surface
CrCl – creatinin clearance in ml/min
Calculation of GFR with Cokroft-Gault formula
(140-age) х body mass (kg) х 88
72 х serum creatinin (mkmol/l)
• For female the result [x 0.85
MDRD formula
GFR = 170 х (Scr х 0.0113)-0.999 х age0.176 х X (urea х 2.8)-0.17 х albumin0.318
(creatinin in mkmol/l, age in years, urea in mmol/l, albumin in g/l)
•For black х 1.18
•For female х 0.762
Those methods can’t be used in patients with low muscle mass, low protein diet, vegetarians, in pregnancy and massive edema
INVESTIRATION OF URINARY TRACT
ULTRASOUNDINTRAVENOUS UROGRAPHYMICTURATING
CYSTOURETHROGRAMRETROGRADE
URETOPELOGRAPHYRENAL ARTERIOGRAPHYISOTOPE RENAL SCANSANTEGRADE NEPHROSTOMY
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