Assessment of renal function Urinalysis Patricia Aristimuño MD

Outline Variability and normal value Measurement Creatinine Urea Cystatin C Markers of tubular damage New markers Urinalysis

Physiologic variability of GFR and normal value What is it? Reductions Normal varies with age, sex, body size, physical activity, diet, pharmacologic therapy, pregnancy. 130 ml/min/1.73m2 men, 120 ml.min/m2 women Normalizing GFR 8% higher in men than women Age decline: 0.75 ml/min per year aftr the age of 40. Pregnancy increases by 50% Diurnal variation Within individual stable. Quite variation among individuals

Measurement Concept of clearance Volume of plasma cleared by a substance per unit of time Substance that is not reabsorbed or secreted The volume of plasma cleared of that substance per unit time is the volume of the GFR

Measurement

Creatinine

CystatinC

Markers of tubular damage Low molecular weight proteins –B2 macroglobulin –Alpha1 macroglobulin N-Acetyl-B-glucosaminidase (NAG)

New markers

Urinalysis

5 year old boy with edema

30 y/o woman with dysuria and hematuria

60 y/o alcoholic who was found unresponsive

10 y/o girsl with history of kidney stones

30 y/o man with history of URI treated with PCN and AKI

83 y/o woman s/p cardiac catheterization x2 and AKI

56 y/o man with 60% BSA burns BP 90/50 on 3 pressors and AKI