Specimen:

Plasma

Collection Medium:

Alternate
Collection Media:

Call laboratory for additional acceptable specimen collection 
containers.

Minimum:

2 ml whole blood in light green top tube or 1 light green microtube for 
pediatric patients

Testing
Schedule:

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

Analytic Time:

2 hours (upon receipt in laboratory)

Reference Range:

0.7-1.4 mg/dl

Pediatric Reference Ranges:

Age              Male     Female   Units
Birth-30 days    0.5-1.2  0.5-0.9  mg/dl
31 days-3 years  0.4-0.7  0.4-0.7  mg/dl
4-6 years        0.5-0.8  0.5-0.8  mg/dl
7-12 years       0.6-1.0  0.6-1.0  mg/dl
13-15 years      0.6-1.2  0.7-1.1  mg/dl
16-18 years      0.8-1.4  0.8-1.2  mg/dl

Test
Limitations:

Criterion: Recovery within plus or minus 10% of initial value.

Icterus: No significant interference up to an I index of 40 
(approximateconjugated bilirubin concentration: 10 mg/dl or 171 
umol/l).

Hemolysis: No significant interference up to an H index of 750 
(approximate hemoglobin concentration: 750 mg/dl or 466 umol/l).

Lipemia (Intralipid): No significant interference up to an L index of 
1000 (approximate triglycerides concentration: 2000 mg/dl or 22.8 
mmol/l). There is poor correlation between turbidity and triglycerides
concentration.

No significant interference by acetone up to 50 mg/dl, acetoacetate up 
to 20 mmol/l and beta-hydroxybutyrate up to 25 mmol/l.

Antibiotics containing cephalosporin lead to significant false-positive 
values (2).

Negatively biased results have been reported (3), due to a temporary 
production of turbidity in the early stages of the reaction. This 
effect correlates with increased triglycerides in the serum sample, but 
does not correlate as well with sample Lipemic Index values. As 
reported,  the effect disappears after overnight storage.

Do not use Creatinine Jaffé for the testing of creatinine in hemolyzed 
samples from neonates, infants or adults with Hb F levels greater than 
or equal to 5% (greater than or equal to 100 mg/dl HbF) (4). In such 
cases, use the Creatinine plus test  (less than or equal to 600 mg/dl 
HbF) to assay the sample.

References:
(1) Glick MR, Ryder KW, Jackson SA. Graphical Comparisons of
    Interferences in Clinical Chemistry Instrumentation. Clin Chem
    1986;32:470-474.

(2) Seelig HP, Wüst H. Ärztl Labor 1969;15:34.

(3) Hortin GL, Goolsby K. Clin Chem 1997;43:408-410.

(4) Mazzachi BC, Phillips JW, Peake MJ. Is the Jaffé creatinine assay
    suitable for neonates? Clin Biochem Revs 1998;19:82.

Methodology:

Spectrophotometery

Sample
Processing:

Centrifuge at 3000 RPM for 10 minutes.
Aliquot plasma into labeled container and cap.

Sample
Storage:

Refrigerate.

Transport
Instructions:

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

CPT Code:

82565

See Additional Information:
Chemistry Pediatric Reference Ranges