Specimen

Plasma

Collection Medium:

Alternate
Collection Media:

Call laboratory for additional acceptable specimen collection 
containers.

Minimum:

2 mls whole blood from light green tope tube or one 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:

2.7-4.5 mg/dl

Pediatric Reference Ranges:

Age        Range    Units
Newborn    4.2-9.0  mg/dl
1 year     3.8-6.2  mg/dl
2-5 years  3.5-6.8  mg/dl

Critical value: <1.0 mg/dl

Test
Limitations:

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

Plasma
Icterus: No significant interference up to an I index of 62.

Hemolysis: Significant positive interference at an H index greater than 
300 (approximate hemoglobin concentration: 300 mg/dl). NOTE: This 
interference results from inorganic phosphates produced by the action 
of phosphatases on organic phosphates, both of which are released from 
the red cell upon hemolysis (2).

Lipemia (Intralipid): No significant interference up to an L index of 
1250.  There is poor correlation between turbidity and triglycerides 
concentration.

Thirty-five commonly used pharmaceuticals were tested in vitro. No 
interference with the assay was found.


References:

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

(2) Tietz NW, ed, Clinical Guide to Laboraotry Tests, 3rd ed. 
Philadelphia, Pa: WB Saunders Company, 1995:486, 487.

Methodology:

Spectrophotometric

CPT Code:

84100

See Additional Information:
Chemistry Critical Lab Values
Chemistry Pediatric Reference Ranges