2-4

Estimated Renal Function

• Estimated GFR = 1.8 x (Cs) x (age)

• Cockcroft-Gault eq.– Estimated creatine clearance (mL/min)

= (140 – age x body weight, kg) 72 x Cs (mg/dl)

-1.154 -0.203

Estimated Renal Function

• Estimated GFR = 1.8 x (Cs) x (age)

= 1.8 x (9.3 mg/dl) x (60) = 0.0598 mL/min per 1.73 m

-1.154 -0.203

-0.203-1.154

2

Estimated Renal Function

• Cockcroft-Gault eq.– Estimated creatinine clearance (mL/min)

= (140 – 60 x 83 kg) 72 x 9.3 mg/dl)= 6640 669.6= 9.916 mL/min

Inulin Renal Clearance• Inulin– A polysaccharide molecule which is not produced in the

body. It is freely filtered and not reabsorbed or secreted by the renal tubules.

– Therefore, the rate at which it is excreted in the urine is equal to its filtration rate.

– Thus, GFR can be calculated as the clearance of the substance

GFR =(Inulin conc in urine) (urine flow rate)

Inulin conc. in plasma

Stages of the development of diabetic nephropathy

• Stage 1 (very early diabetes)—Increased demand upon the kidneys is indicated by an above-normal glomerular filtration rate (GFR).

• Stage 2 (developing diabetes)—The GFR remains elevated or has returned to normal, but glomerular damage has progressed to significant microalbuminuria (30mg/24 hr).

• Stage 3 (overt, or dipstick-positive diabetes) – Glomerular damage has progressed to clinical albuminuria. The urine is “dipstick positive”, containing more than 300 mg of albumin in a 24-hour period. Hypertension typically develops during this stage.

Stages of the development of diabetic nephropathy

• Stage 4 (late-stage diabetes) – Glomerular damage continues, with increasing amounts of protein albumin in the urine. The kidney’s filtering ability has begun to decline steadily, and blood urea nitrogen (BUN) and creatinine (Cr) has begun to increase. The glomerular filtration rate (GFR) decreases about 10% annually. Almost all patients have hypertension at this stage.

• Stage 5 (end-stage renal disease, ESRD) – GFR has fallen to approximately 10 mL per minute (<10mL/min) and renal replacement therapy (i.e. hemodialysis, peritoneal dialysis, kidney transplantation) is needed.