Phosphorus

Test Code

PHOS

Alias/See Also

PO4, Inorganic Phosphorus, PHOS

Preferred Specimen

1.0 mL plasma (0.5 mL minimum)

Transport Container

PST (light green top). Red top and SST also acceptable

Specimen Stability

Room temperature: 8 hours, Refrigerated: 2 days, Frozen: 1 month

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

Grossly hemolyzed specimens are unacceptable.

Reference Range

Age	Female	Male
Adult (>18 years):	2.5 - 4.9 mg/dL	2.5 - 4.9 mg/dL
Pediatric:
0– 30 days	3.1-7.7	2.8-7.0
1 – 2 months	3.1-7.2	3.1-6.6
3 – 12 months	3.1-6.8	3.1-6.6
13 – 23 months	3.1-6.3	3.1-6.2
2 – 12 years	3.1-5.9	3.1-5.9
13 – 15 years	3.1-5.5	3.1-5.3
16 –18 years	3.1-4.8	3.1-5.1

Clinical Significance

Serum phosphorus levels alone are of limited diagnostic value and should be correlated with serum calcium levels. Increased phosphorus with decreased calcium suggests either hypoparathyroidism or renal disease. Decreased phosphorus and 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.