Protein S total antigen results are potentially affected by:
Heparin (unfractionated or low-molecular-weight) >4 U/mL
Hemoglobin >2 g/L
Bilirubin >100 mg/L
Rheumatoid factor >300 IU/mL may lead to an overestimation of the result
Antirabbit antibodies: certain subjects may have aberrant results
Lipemic specimen may lead to an overestimation
Free protein S antigen results are potentially affected by:
Heparin (unfractionated or low-molecular-weight) >4 U/mL
Hemoglobin >200 mg/dL
Bilirubin >25 mg/dL
Triglycerides >1500 mg/dL
Platelets >10
Rheumatoid factor >900 IU/mL
Factor V Leiden variant (APC-R)
Methodology
PSF, PST: Latex Immunoassay (LIA)
Estimated TAT
1-3 days
Testing Schedule
Monday-Friday
Test Includes
Protein S Antigen, Free
CPT Code(s)
85306
Reference Range
Demographic
Free Protein S Antigen (%)
Total Protein S Antigen (%)
Males
65 - 160
80 - 160
Females: < 50 years
50 - 160
70 - 160
Females: ≥ 50 years
65 - 160
80 - 160
Normal, full-term newborn infants or healthy premature infants may have decreased levels of total protein S (15-50%) but because of low levels of C4b-binding protein, free protein S may be normal or near the normal adult level (≥ 50%). Total protein S reaches adult levels by 90 to 180 days postnatal.