Evaluation of an enhanced luminescence assay for alpha-fetoprotein.

Abstract We evaluated a two-site enhanced luminescence immunoenzymometric assay (Amerlite; Amersham International) for alpha-fetoprotein (AFP) in maternal serum and amniotic fluid. The assay is rapid, involving two incubations totalling 4 h. The working range of the assay for serum AFP is 5.5 to 750 kilo-int. units/L (CV less than 10%), with a sensitivity of detection of 0.2 kilo-int. unit/L. The regression equation for the Amerlite assay (y) and our in-house RIA procedure (x) was y = 0.816x + 2.9 (n = 142, r = 0.96). Analytical recovery of added AFP (code 72/227) at three concentrations was 86.7%. Serum AFP concentrations were measured at 15 to 18 weeks of gestation in subjects with normal pregnancies and in subjects whose pregnancies resulted in open neural tube defects; all of the latter had serum AFP concentrations greater than 2.5 multiples of the median. We find the Amerlite system to be an efficient, reliable system for screening for open neural tube defects without use of hazardous radioactive labels.

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Implementation of a screening program for diagnosing open neural tube defects: selection, evaluation, and utilization of alpha-fetoprotein methodology.

Clinical Chemistry ◽

10.1093/clinchem/32.10.1812 ◽

1986 ◽

Vol 32 (10) ◽

pp. 1812-1817 ◽

Cited By ~ 10

Author(s):

R L Christensen ◽

M R Rea ◽

G Kessler ◽

J P Crane ◽

R Valdes

Keyword(s):

Amniotic Fluid ◽

Neural Tube ◽

Neural Tube Defect ◽

Gestational Age ◽

Screening Program ◽

Maternal Serum ◽

Alpha Fetoprotein ◽

Standard Curve ◽

Analytical Recovery ◽

Commercial Kit

Abstract We evaluated and compared three different commercial kit immunoassays for alpha-fetoprotein (AFP) before we implemented our neural tube defect screening program. Each kit can be used with either serum or amniotic fluid. Analytical recovery ranges for AFP reference sera within each kit's standard curve limits (in kilo-int. units/L) were 97-108% (7.5-180) for the Kallestad kit, 77-101% (21.8-436) for Amersham, and 92-100% (0-177) for Hybritech. CVs, within each manufacturer's standard-curve limits, for combined intra-assay (amniotic fluid pools) and inter-assay (kit serum controls) averaged 3.6-7.3% (Kallestad), 2.4-9.3% (Amersham (y) kit results showed a correlation of r = 0.97, y = 1.05x + 5.5 kilo-int. units per liter of maternal serum (n = 66; range, 2.0-98.5). Gestational age did not influence these assay correlations. The Kallestad AFP assay demonstrated a maternal serum positivity rate of 2.9% at greater than or equal to 2.5 (n = 655) and 8.9% at less than 0.5 (n = 423) multiples of the median. All kits performed well analytically.

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Evaluation of a commercial immunoenzymometric assay for alpha-fetoprotein.

Clinical Chemistry ◽

10.1093/clinchem/31.11.1868 ◽

1985 ◽

Vol 31 (11) ◽

pp. 1868-1870 ◽

Cited By ~ 4

Author(s):

D A Hullin ◽

J S Woodhead

Keyword(s):

Retrospective Study ◽

Amniotic Fluid ◽

Neural Tube ◽

Neural Tube Defects ◽

Screening Program ◽

Maternal Serum ◽

Alpha Fetoprotein ◽

Sequential Measurement ◽

Antenatal Detection ◽

Outcome Performance

Abstract A two-site immunoenzymometric assay (Abbott Diagnostics) for alpha-fetoprotein (AFP) in maternal serum and amniotic fluid has been evaluated for its suitability as a screening test for open neural tube defects. In a retrospective study based on 190 pregnancies of known outcome, performance of the kit in measuring both serum and amniotic fluid AFP correlated well with that of an in-house radioimmunoassay. Of 39 pregnancies associated with open neural tube defects, only four would not have been detected by the use of sequential measurement of serum and amniotic fluid AFP (also essentially in agreement with results obtained by the RIA). We conclude that this immunoassay could form the basis for a screening program for antenatal detection of open neural tube defects.

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Amniotic Fluid and Maternal Serum Alpha-fetoprotein Determination in Neural Tube Defects

Developmental Medicine & Child Neurology ◽

10.1111/j.1469-8749.1974.tb03460.x ◽

2008 ◽

Vol 16 ◽

pp. 122-125 ◽

Cited By ~ 5

Author(s):

N. C. NEVIN

Keyword(s):

Amniotic Fluid ◽

Neural Tube ◽

Neural Tube Defects ◽

Maternal Serum ◽

Alpha Fetoprotein ◽

Serum Alpha Fetoprotein

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Acetylcholinesterase and fetal malformations: modified qualitative technique for diagnosis of neural tube defects.

Clinical Chemistry ◽

10.1093/clinchem/27.1.61 ◽

1981 ◽

Vol 27 (1) ◽

pp. 61-63 ◽

Cited By ~ 27

Author(s):

J E Haddow ◽

M E Morin ◽

M S Holman ◽

W A Miller

Keyword(s):

Amniotic Fluid ◽

Neural Tube ◽

Neural Tube Defects ◽

False Positive ◽

Alpha Fetoprotein ◽

Blind Study ◽

Fetal Malformations ◽

Qualitative Technique ◽

Single Blind ◽

Positive Results

Abstract A single-blind study involving amniotic-fluid samples from 214 pregnancies of known outcome confirms that an electrophoretically distinct isoenzyme of acetylcholinesterase is associated with fetal open neural tube defects. Furthermore, only one of 13 amniotic-fluid samples with false-positive results for alpha-fetoprotein showed the characteristic isoenzyme, indicating that qualitative acetylcholinesterase assessment can decrease the proportion of false positives from the alpha-fetoprotein assay. We have also identified this characteristic isoenzyme in amniotic fluids from pregnancies in which other serious fetal defects occurred. A detailed electrophoresis protocol for identifying this characteristic isoenzyme is described.

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Concanavalin A binding of alpha-fetoprotein in amniotic fluid as an aid in the diagnosis of neural tube defects.

Clinical Chemistry ◽

10.1093/clinchem/27.10.1658 ◽

1981 ◽

Vol 27 (10) ◽

pp. 1658-1660 ◽

Cited By ~ 8

Author(s):

P K Buamah ◽

P Taylor ◽

A M Ward

Keyword(s):

Spina Bifida ◽

Amniotic Fluid ◽

Neural Tube ◽

Neural Tube Defects ◽

Concanavalin A ◽

Gestational Age ◽

Alpha Fetoprotein ◽

Normal Outcome ◽

Fetal Malformations ◽

Open Spina Bifida

Abstract Concanavalin A nonreactive alpha-fetoprotein was determined in samples of amniotic fluid from 16 abnormal pregnancies complicated by anencephaly (7), open spina bifida (6), intra-uterine death (1), anencephaly with exomphalos (1), or open spina bifida with exomphalos (1), and in amniotic fluid from 50 normal pregnancies with gestational age between 13 and 24 weeks. In all 16 cases with fetal malformations, the proportion of nonreactive alpha-fetoprotein was significantly decreased (median 5.3%) as compared with amniotic fluid from pregnancies with a normal outcome (median 39.7%). The results confirm that this measurement is useful in the diagnosis of neural tube defects, especially when the concentration of alpha-fetoprotein in amniotic fluid is normal or only slightly above normal and gestational age is uncertain.

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