Creatinine

375

eGFR

1 mL serum collected in a serum separator tube (SST)

0.5 mL

Plasma collected in a: sodium or lithium heparin (green-top) tube

Centrifuge serum specimens within 1 hour of collection, transfer serum to a sterile, plastic screw-capped vial(s), ship at room temperature.

Plastic screw-cap vial

Room temperature

Room temperature: 7 days
Refrigerated: 7 days
Frozen: 28 days

Grossly icteric • Anticoagulants other than heparin

Set up: Daily; Report available: Next day

Creatinine
Age	Male (mg/dL)	Female (mg/dL)
≤2 days	0.79-1.58	0.79-1.58
3-27 days	0.35-1.23	0.35-1.23
1 month-9 years	0.20-0.73	0.20-0.73
10-12 years	0.30-0.78	0.30-0.78
13-15 years	0.40-1.05	0.40-1.00
16-17 years	0.60-1.20	0.50-1.00
18-29 years	0.60-1.24	0.50-0.96
30-39 years	0.60-1.26	0.50-0.97
40-49 years	0.60-1.29	0.50-0.99
50-59 years	0.70-1.30	0.50-1.03
60-69 years	0.70-1.35	0.50-1.05
70-79 years	0.70-1.28	0.60-1.00
≥80 years	0.70-1.22	0.60-0.95

For patients >49 years of age, the upper reference limit for creatinine is approximately 13% higher for people identified as African-American.

eGFR	≥60 mL/min/1.73m2

Serum creatinine is useful in the evaluation of kidney function and in monitoring renal dialysis. A serum creatinine result within the reference range does not rule out renal function impairment: serum creatinine is not sensitive to early renal damage since it varies with age, gender and ethnic background. The impact of these variables can be reduced by an estimation of the glomerular filtration rate using an equation that includes serum creatinine, age and gender.