Protein C and Protein S
Protein C activity or protein C functional; protein C antigen; Protein S antigen, free.
To assess coagulation function and assist in diagnosis of disorders such as thrombosis related to protein C and protein S deficiency.
There are no food, fluid, or activity restrictions unless by medical direction. Patients should discontinue warfarin therapy for 2 wk prior to specimen collection, as ordered. Specimen collection should not be performed sooner than 10 days following a thrombotic or clotting event.
|Age||Protein C Activity or Functional Protein C (Method: Electromagnetic Mechanical Clot Detection)||Age||Protein C Antigen (Method: Enzyme Immunoassay)|
|3–6 mo||28%–80%||3–6 mo||28%–80%|
|1–6 yr||40%–90%||1–6 yr||40%–90%|
|7–11 yr||68%–140%||7–11 yr||68%–140%|
|12–13 yr||65%–160%||12–13 yr||65%–160%|
|14 yr–Adult||70%–170%||14 yr–Adult||70%–140%|
|Values are significantly reduced in children because of liver immaturity. Functional Protein C and Free Protein S antigen, free are recommended for initial screening of Protein C and Protein S deficiency. The two are initially tested together because a deficiency in Protein S may affect Protein C activity. Protein C antigen is used to further distinguish inherited type 1 from inherited type 2 protein C deficiency.|
|Age||Protein S Free Antigen (Method: Microlatex Particle-Mediated Immunoassay)||Age||Protein S Activity or Functional Protein S (Method: Electromagnetic Mechanical Clot Detection)||Age||Protein S Total Antigen (Method: Enzyme Immunoassay)|
|Newborn–3 mo||15%–55%||Newborn–3 mo||15%–55%||Newborn||12%–60%|
|3–6 mo||35%–90%||3–6 mo||35%–90%||1 wk–29 day||25%–80%|
|7–12 mo||45%–115%||7–12 mo||45%–115%||1–89 day||30%–95%|
|1–5 yr||60%–120%||1–5 yr||60%–120%||3 mo–5 yr||55%–120%|
|6–9 yr||60%–130%||6–13 yr||60%–150%||6–10 yr||40%–115%|
|10–17 yr||60%–140%||14–17 yr||50%–145%||11 yr–Adult male||85%–135%|
|18 yr–Adult male||75%–145%||18 yr–Adult male||70%–140%||11 yr–Adult female||65%–130%|
|18 yr–Adult male||55%–125%||18 yr–Adult female||60%–130%|
|Values are significantly reduced in children because of liver immaturity; levels reach normal adult levels within 3 to 6 months of age. Protein S Free Antigen or Functional Protein S may be used to identify Protein S deficiency. Protein S Total Antigen is used to further distinguish inherited types I, II, or III Protein S deficiency.|
Critical Findings and Potential Interventions
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