Pediatric GFR
Epic Lab Code: LAB7477
Downtime Form: A-1a General Laboratory Requisition
Chemistry
6240 RCP
356-3527
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 16-17 years old 0.6 - 1.2 mg/dL Females 16-17 years old 0.5 - 1.0 mg/dL Note: There are gender-specific ranges only for ages 16 and 17 years old only.
Comments:
This order is for a plasma creatinine, with the estimated glomerular filtration rate (GFR) calculated by the pediatric Schwartz equation:

   GFR (mL/min/1.73 m^2) = (0.41 x Height) / (Plasma creatinine)
     [Height in cm; plasma creatinine in mg/dL]

This order requires that the ordering LIP input the height in centimeters (cm) at the time of placing the order. Please use caution when placing future orders, especially if the height is likely to change significantly when the order is released and the blood sample drawn.

This order cannot be carried out for patients 18 years or older as the Schwartz equation is not recommended for adult patients.

This order is NOT recommended for premature infants in the first several months of life, for which more specialized equations for estimated GFR are indicated.

References:
1. National Kidney Foundation

2. National Kidney Disease Education Program (NKDEP)

3. Lamb EJ, Tomson CRV, Roderick PJ. Estimating kidney function in adults using formulae. Ann Clin Biochem 2005; 42:321-345.

4. Schwartz GJ, et al. New equations to estimate GFR in children with CKD. J Am Soc Nephrol. 2009; 20: 629-637.

5.Schwartz GJ and Work DF. Measurement and estimation of GFR in children and adolescents.
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
CPT Code:
82565