Table 2.
False-positive immunoassay results in a multicentre study of 74 analytes 98
| Analyte | No. of assay systems tested | Number (%) of heterophile false-positives per number of analyses performeda | Number (%) of false-positives of uncertain etiology per number of analyses performedb |
|---|---|---|---|
| Thyroglobulin Antibody | 3 | 2/19 (11%) | 4/19 (21%) |
| AFPc | 12 | 0/105 | 9/105 (8.6%) |
| β-hCG + hCG | 15 | 14/281 (5.0%) | 26/281 (9.3%) |
| CA 19-9d | 10 | 1/84 (1.2%) | 9/84 (11%) |
| Cortisol | 8 | 0/85 | 17/85 (20%) |
| Estradiol | 7 | 3/59 (5.1%) | 34/59 (58%) |
| FSH / LH | 12 | 0/136 | 9/136 (6.6%)g |
| Myoglobin | 7 | 28/59 (48%) | 0/59 |
| PTHe | 4 | 6/43 (14%) | 1/43 (2.3%) |
| TNIf | 9 | 18/156 (12%) | 9/156 (5.8%) |
| TSH | 14 | 10/249 (4.0%) | 4/249 (1.6%) |
a
Heterophile false-positive when immunoassay result was elevated above the reference interval and restored to within the reference interval by pre-treatment with heterophile blocking reagent, or within the reference interval but nevertheless reduced by >30% by pre-treatment with heterophile blocking reagent.
b
Abnormally increased results that were not restored to within the reference interval by pre-treatment with heterophile blocking reagent.
c
AFP, α-fetoprotein
d
CA 19-9, cancer antigen 19-9
e
PTH, parathyroid hormone
f
TNI, cardiac troponin I
g
Results were false-negative