Performance characteristics of the Access Inhibin A assay.
BACKGROUND
Second trimester maternal screening using AFP, uE3, hCG, and inhibin A has shown a detection rate for Down's syndrome of 81% with a 5% false positive rate. Inhibin A may also have utility as a serum tumor marker in postmenopausal women with ovarian cancer and men with testicular stromal tumors.


METHODS
The Beckman Coulter Access Inhibin A assay was evaluated for limit of blank, dilution linearity, imprecision, interferences, reference intervals, and comparison to an inhibin A ELISA.


RESULTS
The limit of blank was 0.1 ng/l. The assay was linear from 0.2 to 1347 ng/l. Total inter-assay CVs were <5% for control levels ranging from 24.6 ng/l to 811 ng/l. Interference studies showed recoveries of inhibin A within 10% of expected values at interferent concentrations of 10 g/l hemoglobin and 22 g/l triglycerides. No significant interference was observed at a bilirubin concentration of 400 mg/l. The 97.5th percentile upper reference limits were 6.8 ng/l for postmenopausal women and 3.0 ng/l for men. The Access assay compared to an ACTIVE ELISA showed a slope of 0.88, an intercept of -3.7 ng/l, S(y/x)=40 ng/l, and r=0.98.


CONCLUSIONS
The analytical performance of the Access inhibin A assay is acceptable for routine laboratory testing.
Rawlins
Mindy L
ML
ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, UT 84108, USA.
La'ulu
Sonia L
SL
Erickson
J Alan
JA
Roberts
William L
WL
D004314:Down Syndrome / Q000175:diagnosis*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007265:Inhibins / Q000097:blood*; D008297:Male; D010051:Ovarian Neoplasms / Q000175:diagnosis*; D011247:Pregnancy; D011296:Prenatal Diagnosis; D015203:Reproducibility of Results; D013736:Testicular Neoplasms / Q000175:diagnosis*
C422362:inhibin A; D007265:Inhibins