Comparison of protein S functional and antigenic assays in normal pregnancy

OBJECTIVE: Our purpose was to determine the effect of pregnancy on the protein S functional assay (clot based), which is used to screen for all subtypes of protein S deficiency states, and to compare its behavior in pregnancy with antigenic assays. STUDY DESIGN: This was a cross-sectional study of 3...

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Bibliographic Details
Published in:American journal of obstetrics and gynecology 1996-09, Vol.175 (3), p.657-660
Main Authors: LEFKOWITZ, J. B, CLARKE, S. H, BARBOUR, L. A
Format: Article
Language:English
Subjects:
Adolescent
Adult
Antigens - blood
Biological and medical sciences
Complement Inactivator Proteins
Cross-Sectional Studies
Factor V - analysis
Factor VIII - analysis
Female
functional testing
Glycoproteins
Gynecology. Andrology. Obstetrics
Humans
Management. Prenatal diagnosis
Medical sciences
Partial Thromboplastin Time
Pregnancy
Pregnancy. Fetus. Placenta
Protein S
Protein S - analysis
Protein S - immunology
Protein S - physiology
Protein S Deficiency - blood
Protein S Deficiency - diagnosis
Receptors, Complement - blood
Reference Values
Time Factors
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Summary:OBJECTIVE: Our purpose was to determine the effect of pregnancy on the protein S functional assay (clot based), which is used to screen for all subtypes of protein S deficiency states, and to compare its behavior in pregnancy with antigenic assays. STUDY DESIGN: This was a cross-sectional study of 37 normal pregnant women without thromboembolic risks who were tested by both functional and antigenic protein S assays during the first, second, and third trimesters. RESULTS: Mean protein S functional levels decline strikingly from the first to the third trimester, all 10 third-trimester patients had functional protein S levels well below the lower limit of the reference range. In contrast, only 3 of 10 third-trimester and none of the second-trimester patients had free protein S antigenic levels below the reference range. CONCLUSIONS: The protein S functional assay should not be used in pregnancy to screen for the subtypes of protein S deficiency; misdiagnosis and inappropriate treatment could result. (Am J Obstet Gynecol 1996;175:657-60.)
ISSN:0002-9378
1097-6868
DOI:10.1053/ob.1996.v175.a73866