A serum creatinine test measures the level of creatinine in your blood and provides an estimate of how well your kidneys filter (glomerular filtration rate).

Also Known As: Creat, Blood Creatinine, Serum Creatinine,
Panel Tests: Urea, Blood Urea Nitrogen, Creatinine, Calcium, Phosphorus, Albumin, Magnesium, Total Protien, Electrolytes,
Test Procedure:
Method: Colorimetric, 2 Point Kinetic, “mod. Jaffe”, Increasing reaction
TEST PRINCIPLE:
Creatinine forms a colored orange-red complex in an alkaline picrate solution. The difference in absorbance at fixed times during conversion is proportional to the concentration of creatinine in the sample.
Kit Componants:
- Reagent 1 (R1):
- Reagent 2 (R2):
- Standard: 2.0 mg/dl
REAGENT COMPOSITION
COMPONENTS | CONCENTRATIONS |
---|---|
Reagent 1 (R1) | |
Sodium Hydroxide | 0.2 mol/L |
Reagent 2 (R2) | |
Picric Acid | 20 mmol/L |
REAGENT PREPARATION:
Substrate Start: The reagents are ready to use.
Sample Start: Mix 4 parts of Reagent 1 with 1 part of Reagent 2. (= Working Reagent)
Sample Preparation:
- Serum: No Need any Preparation
- Urine: Dilute urine 1 + 49 with distelled water.
Test Parameters:
Method | Colorimetric, 2 Point Kinetic, “mod. Jaffe”, Increasing reactio |
Wavelength | Hg 492 nm (490 nm – 510 nm) |
Temperature | 20°C-25°C / 37°C |
Sample | Serum, heparin plasma, urine |
Linearity | up to 15 mg/dL (1330 µmol/L) |
Sensitivity | The lower limit of detection is 0.2 mg/dL |
MANUAL TEST PROCEDURE
Bring reagents and samples to room temperature.
Substrate Start :
Pipette into test tubes | Blank | Std/Cal. | Sample |
---|---|---|---|
Reagent 1 | 1000 µl | 1000 µl | 1000 µl |
Sample | – | – | 50 µL |
Std./Cal. | – | 50 µL | – |
Mix. Incubate 0 – 5 min., then add: | |||
Reagent 2 | 250 µL | 250 µL | 250 µL |
Mix. Incubate 1 min. and read A1against reagent blank. Incubate for exactly 2 min. and read A2 against reagent blank. Calculate: ΔA = (A2 – A1) sample or stdandard |
Sample Start :
Pipette into test tubes | Blank | Std/Cal. | Sample |
---|---|---|---|
Working Reagent | 1000 µL | 1000 µL | 1000 µL |
Sample | – | – | 50 µL |
Std./Cal | – | 50 µL | – |
Mix. Incubate 1 min. and read A1 against reagent blank. Incubate for exactly 2 min. and read A2 against reagent blank. Calculate: ΔA = (A2 – A1) sample or standard |
CALCULATION (light path 1 cm)

The calculated creatinine clearance refers to the average body surface of an adult (1.73 m2).
For serum creatinine (sCr) [mg/dL]:
GFR = 175 x sCr-1.154 x age-0.203 x 1.212 (if Afro-American) x 0.742 (if female)
For serum creatinine (sCr) [µmol/L]:
GFR = 30849 x sCr-1.154 x age-0.203 x 1.212 (if Afro-American) x 0.742 (if female)
Normal Ranges:
Serum/ Plasma:
- 0.6 – 1.1 mg/dl
Urine:
- 11 – 20 mg/kg/24h
Creatinine Clearance:
- 95 – 160 mL/min/1.73 m2
- Read more about Blood Creatinine
- Read more about Urine Creatinine
- Read more about Creatinine Clearance
⚠️ Disclaimer:
The content on LabTestsGuide.com is for informational and educational purposes only. We do not guarantee the accuracy, completeness, or timeliness of the information provided. Always consult qualified healthcare professionals for medical advice, diagnosis, or treatment. LabTestsGuide.com is not liable for any decisions made based on the information on this site.