Gates developed equations for predicting the glomerular filtration rate (GFR) from serum creatinine, gender, and age. The author is from Good Samaritan Hospital in Portland, Oregon.
(1) serum creatinine in mg/dL
(2) age in years (with age set to 20 if true age < 20 years)
estimated GFR for a male in mL per min per 1.73 square m BSA =
= 89.4 * (((creatinine)^(-1.2)) + (0.005 * (55 - (age in years)) * ((creatinine)^(-1.1))))
estimated GFR for a female in mL per min per 1.73 square m BSA =
= 60 * (((creatinine)^(-1.1)) + (0.005 * (56 - (age in years)) * ((creatinine)^(-1.1))))
• The 0.005 (rounded up from 0.00475) factor indicates the annual decline in inulin clearance per year, assuming a decline of 4.75% every 10 years.
• The author compared his method with those of (1) Jeliffe and (2) Cockcroft and Gault. This estimate performed fairly well except at very low and very high GFRs.
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Specialty: Nephrology, Clinical Laboratory