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Heparin cofactor assay, AT-III.

Common Use:
To assist in diagnosing heparin resistance or disorders resulting from a hypercoagulable state such as thrombus.

Plasma collected in a completely filled blue-top (3.2% sodium citrate) tube. If the patient’s hematocrit exceeds 55%, the volume of citrate in the collection tube must be adjusted.

Normal Findings:
(Method: Chromogenic Immunoturbidimetric)

AT-III Activity
AgeConventional Units (% of Normal)
1–4 days39–87
5–29 days41–93
1–3 mo48–108
3–6 mo73–121
6–12 mo84–124
1–5 yr82–139
6–17 yr90–131
18 yr–older adult80–120
AT-III antigen
6 mo–Adult82–136

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