ad. 7. Questionable results of fβ-HCG + PAPP-A test.
Every result of a biochemical fβ-HCG + PAPP – A test should be consulted with a specialist and only they can interpret the results correctly! The values of the laboratory results received by a patient are provided in international units (IU/l) or others with a quantitative characteristic. Therefore, presenting the results in certain units, essential for interpretation (a multiple of the median MoM), requires tools and medical knowledge.
Suspicious values of biochemical parameters for the Down syndrome are as follows: if the value of fβ-HCG exceeds 2.52 MoM and the value of PAPP-A is below 0.5 MoM; for Edwards’ and Patau syndrome (Trisomy 18 and 13): if the values of both parameters are below 0.33 MoM; for Turner syndrome: if value of PAPP-A is below 0.5 MoM and fβ-HCG is 1 MoM; for triploidy syndrome: if values of fβ-HCG and PAPP-A are both below 0.1 MoM or exceed 5 MoM.
Reliable biochemical examinations can be performed in laboratories carrying out a great number of tests (local population norms are important) on an accredited analyzer, e.g. Kryptor made by Brahms (available in Poland in “Diagnostyka” network), where a strict assessment of the quality of assays is maintained.
A biochemical examination should always be confronted with a detailed ultrasound scan. For example, it is possible that the biochemical results show low levels of both previously mentioned parameters, which indicates a higher risk of trisomy 13 and 18, but if an ultrasound scan (including the assessment of early fetal anatomy) does not present any anomalies, in fact, the genetic risk is not increased.
We would like to ask our patients and their partners not to interpret the results on their own, as it might lead to unnecessary stress.