Creatinine

Label Mnemonic:	CRT
Epic code:	LAB66
Order form:	Laboratory Requisition
Supply order:	Supply Order Form
Billing:	Billing Policies
CPT code:	82565

Specimen(s):

Plasma

Collection Medium:

Plasma Separator Tube 4.5 mL

Alternate Collection Media:

Call laboratory for additional acceptable specimen collection containers.

Minimum:

3 mL whole blood in light green top tube or 1 Microtainer^® for pediatric patients

Testing Schedule:

24 hrs/day, 7 days a week, including holidays.

Turn Around Time:

1 hour (upon receipt in laboratory)

Reference Range:

Premature                     0.3 - 1.0 mg/dL
Neonates                      0.2 - 0.9 mg/dL
2-12 months                   0.2 - 0.4 mg/dL
1-2 years                     0.2 - 0.5 mg/dL
3-4 years                     0.3 - 0.7 mg/dL
5-6 years                     0.3 - 0.7 mg/dL
7-8 years                     0.2 - 0.6 mg/dL
9-10 years                    0.3 - 0.7 mg/dL
11-12 years                   0.3 - 0.9 mg/dL
13-15 years                   0.4 - 0.9 mg/dL

Males 16 years and older      0.6 - 1.2 mg/dL
Females 16 years and older    0.5 - 1.0 mg/dL

Note: There are gender-specific ranges only for ages 16 years and 
older.

Comments:

Refer to BD Microtainer^® Tubes product sheet for detailed sample collection instructions.

Estimated glomerular filtration rate (eGFR) calculation for patients 18 years and older shifted to 2021 CKD-EPI creatinine refit without the race variable equation on August 16, 2022.

References:
1. National Kidney Foundation

2. National Kidney Disease Education Program (NKDEP)

3. National Kidney Foundation eGFR Calculator

4. Delgado C et al. A Unifying Approach for GFR Estimation: Recommendations of the NKF-ASN Task Force on Reassessing the Inclusion of Race in Diagnosing Kidney Disease.
Am J Kidney Dis. 2022 Feb;79(2):268-288.e1. doi: 10.1053/j.ajkd.2021.08.003.

Test Limitations:

Icterus: No significant interference up to an I index of 60 (approximate conjugated and unconjugated bilirubin concentration: 60 mg/dL).

Hemolysis: No significant interference up to an H index of 800.

Lipemia (Intralipid): No significant interference up to an L index of 2000 (approximate triglycerides concentration: 4000 mg/dL). There is poor correlation between turbidity and triglycerides concentration.

Ascorbic acid < 300 mg/L (< 1.7 mmol/L) does not interfere.

Calcium dobesilate (e.g. Dexium) gives falsely low recoveries from 12.0 μmol/L (5 mg/L). Cyanokit (hydroxocobalamin) at therapeutic levels causes significantly higher results.

N-ethylglycine at therapeutic concentrations and DL-proline at concentrations > 1 mmol/L (115 mg/L) give falsely high results. No significant interference up to a creatine level of 4 mmol/L (524 mg/L).

Cephalosporin antibiotics do not affect this test. 2-Phenyl-1,3- indandion (Phenindion) at therapeutic concentrations interferes with the assay.

Hemolyzed samples from neonates, infants or adults with HbF values > 600 mg/dL interfere with the test.

In very rare cases gammopathy, in particular type IgM (Waldenström's macroglobulinemia), may cause unreliable results.

For diagnostic purposes, the results should always be assessed in conjunction with the patient's medical history, clinical examination and other findings.

Methodology:

Enzymatic Colorimetric

Sample Processing:

Centrifuge at a speed and time necessary to get barrier separation of plasma/serum and cells within 1 hour of collection. Send specimen in original tube. Do Not transfer to another tube.
Each sample must be labeled with at least TWO full patient identifiers (First/Last Name & DOB are sufficient for non-UIHC affiliated clients) to avoid sample rejection/delays.

Sample Storage:

Refrigerate.
All sample storage requirements are intended for delivery to UIHC within 24 hours of collection for testing. If samples won't arrive in this time period, please call the UIHC Core Lab for alternative storage/shipping instructions (319-356-3527).

Transport Instructions:

Place labeled specimen into zip-lock type biohazard bag; seal bag.
Place completed requisition into outside pocket of bag.
Transport in cooler with refrigerated coolant packs.

CPT Code:

82565