Phosphate (as Phosphorus)

Test Code

718

CPT Codes
84100

Preferred Specimen

1 mL serum collected in a serum separator tube (SST)

Minimum Volume

0.5 mL

Transport Container

Plastic screw-cap vial

Transport Temperature

Room temperature

Specimen Stability

Room temperature: 72 hours
Refrigerated: 7 days
Frozen: 28 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Gross hemolysis • Plasma

Methodology
Spectrophotometry (SP)

Setup Schedule

Set up: Daily; Report available: Next day

Reference Range

No age	2.5-4.5 mg/dL
<7 Days	4.0-9.0 mg.dL
7 Days-2 Years	4.0-8.0 mg/dL
3-12 Years	3.0-6.0 mg/dL
13-15 Years	3.2-6.0 mg/dL
16-18 Years	3.0-5.1 mg/dL
19-20 Years	2.7-5.0 mg/dL
21-64 Years	2.5-4.5 mg/dL
>64 Years	2.1-4.3 mg/dL

Clinical Significance

Serum phosphorus (Phosphate) levels alone are of limited diagnostic value and should be correlated with serum calcium levels. An increased phosphorus with decreased calcium suggests either hypoparathyroidism or renal disease. A decreased phosphorus and an increased calcium suggests hyperparathyroidism or sarcoidosis. When both calcium and phosphorus are decreased diagnostic considerations include malabsorption, vitamin D deficiency and renal tubular acidosis. Increased phosphorus and normal or increased calcium suggests Milk-alkali syndrome or hypervitaminosis D.

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.