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Test Code CRTS1 Creatinine with Estimated Glomerular Filtration Rate (eGFR), Serum


Necessary Information


Patient's age and sex are required.



Specimen Required


Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL

Collection Instructions:

1. Serum gel tubes should be centrifuged within 2 hours of collection.

2. Red-top tubes should be centrifuged and the serum aliquoted into a plastic vial within 2 hours of collection.


Useful For

Diagnosing and monitoring treatment of acute and chronic kidney diseases

 

Adjusting dosage of renally excreted medications

 

Monitoring kidney transplant recipients

 

Estimating glomerular filtration rate for people with chronic kidney disease (CKD) and those with risk factors for CKD (diabetes, hypertension, cardiovascular disease, and family history of kidney disease)

Reporting Name

Creatinine with eGFR, S

Specimen Type

Serum

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 7 days
  Frozen  90 days
  Ambient  24 hours

Reject Due To

Gross hemolysis Reject

Reference Values

CREATININE

Males(1)

0-11 months: 0.17-0.42 mg/dL

1-5 years: 0.19-0.49 mg/dL

6-10 years: 0.26-0.61 mg/dL

11-14 years: 0.35-0.86 mg/dL

≥15 years: 0.74-1.35 mg/dL

 

Females(1)

0-11 months: 0.17-0.42 mg/dL

1-5 years: 0.19-0.49 mg/dL

6-10 years: 0.26-0.61 mg/dL

11-15 years: 0.35-0.86 mg/dL

≥16 years: 0.59-1.04 mg/dL

 

ESTIMATED Glomerular Filtration Rate (eGFR)

≥18 years old: ≥60 mL/min/BSA (body surface area)

 

Note: eGFR results will not be calculated for patients younger than 18 years old.

Estimated GFR calculated using the 2021 CKD-EPI creatinine equation

2021 CKD-EPI creatinine eGFR not valid for patients younger than 18 years old.

Method Description

Creatinine:

This enzymatic method is based on the conversion of creatinine, with the aid of creatininase, creatinase, and sarcosine oxidase, to glycine, formaldehyde, and hydrogen peroxide. Catalyzed by peroxidase, the liberated hydrogen peroxide reacts with 4-aminophenazone and hydroxy(tosyloxy)iodobenzene (HTIB) to form a quinone imine chromogen. The color intensity of the quinone imine chromogen formed is directly proportional to the creatinine concentration in the reaction mixture.(Package insert: cobas creatinine reagent. Roche Diagnostics; 12/2016)

 

Estimated Glomerular Filtration Rate:

Estimated GFR (eGFR) is calculated using the 2021 Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation:

Females:

If creatinine ≤0.7 mg/dL: 142 x (Scr/0.7)(-0.241) x 0.9938age x 1.012

If creatinine >0.7 mg/dL: 142 x (Scr/0.7)(-1.200) x 0.9938age x 1.012

 

Males:

If creatinine ≤0.9 mg/dL: 142 x (Scr/0.9)(-0.302) x 0.9938age

If creatinine >0.9 mg/dL: 142 x (Scr/0.9)(-1.200) x 0.9938age

Values are reported for calculated glomerular filtration rate (GFR) estimates between 15-90 mL/min/1.73 m(4). Estimated GFR values outside of this range are reported as "<15 mL/min/1.73 m(2)" or ">90 mL/min/1.73 m(4)" and not as an exact number.

Day(s) Performed

Monday through Sunday

Report Available

Same day/1 to 2 days

Specimen Retention Time

1 week

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

82565

LOINC Code Information

Test ID Test Order Name Order LOINC Value
CRTS1 Creatinine with eGFR, S 45066-8

 

Result ID Test Result Name Result LOINC Value
CRTSA Creatinine, S 2160-0
EGFR1 Estimated GFR (eGFR) 98979-8

Forms

If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:

-Kidney Transplant Test Request

-Renal Diagnostics Test Request (T830)