SEQC Spanish Society of Laboratory Medicine

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• “Screening, diagnosing, and monitoring both thyroid dysfunctions and gestational diabetes help prevent complications and ensure the health of the mother and baby,” explains Dr. Gregori Casals, from the Biochemistry and Molecular Genetics Service at the Hospital Clínic de Barcelona

• The fetal DNA test in maternal blood presents detection rates of 95% of the most common trisomies (Down, Patau and Edwards syndromes)

Bilbao, November 21, 2024 – The development of new strategies in the screening for preeclampsia during the second and third trimester of pregnancy, gestational diabetes,and prenatal diagnosis are some of the areas of Laboratory Medicine that were addressed in the new edition of the National Clinical Laboratory Congress (LABCLIN 2024), which was held from November 20 to 22 in Bilbao.

The congress was organized by the Spanish Society of Laboratory Medicine (SEQC^ML), the Spanish Association of Medical Biopathology (AEBM-ML) and the Spanish Association of Clinical Laboratory Medicine (AEFA), and brought together more than 1,200 health professionals. It was a great opportunity to attend discussion panels and scientific activities organized by the different scientific societies, as well as different symposia where one could delve deeper into and analyze the main innovations in Laboratory Medicine.

Specifically, the symposium, “The laboratory in maternal-fetal medicine: current situation and future prospects” moderated by Dr. Belén Prieto, clinical biochemist of the Metabolic and Population Screening Section in the Clinical Biochemistry Service at the Central University Hospital of Asturias in Oviedo, will delve into the work of the Clinical Laboratory specialist in the areas of thyroid dysfunction in pregnancy, gestational diabetes, and prenatal diagnosis of chromosomal abnormalities (TPNI).

Thyroid dysfunction and gestational diabetes during pregnancy 

Thyroid disorders that occur during pregnancy are common and can cause negative effects for both the mother and the fetus. Therefore, it is important to make a correct and early diagnosis in order to carry out an effective therapy that reduces risks. In this sense, Laboratory Medicine plays a key role in “screening, diagnosis and monitoring both thyroid dysfunctions and gestational diabetes, allowing for early and appropriate intervention that helps prevent complications and ensure the health of the mother and baby,” according to Dr. Gregori Casals, member of the Hormones Commission and the Biochemical Assessment Commission for Liver Disease of the SEQC^ML and consultant for the Biochemistry and Molecular Genetics Service of the Hospital Clínic de Barcelona. 

The most common thyroid dysfunction in pregnancy is hypothyroidism (insufficient thyroid activity), which if left untreated can lead to complications such as an increased risk of spontaneous abortion (miscarriage), premature birth, and alterations in fetal neurological development. “The main biochemical test for its detection is the measurement of thyrotropin (TSH) which, if altered, must be complemented with a more complete study of thyroid function,” explains Dr. Casals. 

As the researcher points out, gestational diabetes is characterized by glucose intolerance, mediated in part by hormonal changes that increase insulin resistance. “It can cause complications such as fetal macrosomia (the baby is born with a greater than normal weight), difficult delivery, and a higher risk of type 2 diabetes and repeated gestational diabetes in a future pregnancy.” Similarly, “for screening and diagnosis there are various protocols based on the determination of glucose intolerance,” adds Dr. Casals. 

Protocols for monitoring pregnancy and acting in accordance

At a territorial level, and specifically in the Basque Country, according to Dr. Eva Barrenechea Iparraguirre, a specialist in the Biochemistry Service of the Galdakao-Usansolo Hospital in Bizkaia, “pregnancy requires adequate monitoring, in order to control possible alterations that may appear and prevent them or diagnose them early, especially those with a higher prevalence, such as diabetes.” In the words of the speaker, “the laboratory performs an oral glucose tolerance test on pregnant women to see whether or not they have developed gestational diabetes, and to be able to not only monitor the health of the pregnant woman, but also that of her future baby, as well as prevent future complications.” 

Currently, there are many protocols for monitoring pregnancy. “Some of those we have implemented in our center are: screening for thyroid dysfunction, anemia, infections prior to pregnancy, preeclampsia, and chromosomal abnormalities,” explains the specialist. 

The role of Laboratory Medicine in monitoring the mother's health during pregnancy and identifying the risk of complications, such as preeclampsia, is also important. In addition, the importance of carrying out nutritional status assessments and screening tests to detect metabolic or genetic disorders was highlighted.

At this time, "Osakidetza has launched a preeclampsia screening programme to identify those pregnant women at higher risk of developing it and to be able to establish a preventive treatment that reduces the risk of serious complications during pregnancy and premature birth," adds Dr. Barrenechea.

Prenatal Diagnosis (non-invasive prenatal test)

When specialists talk about NIPT (non-invasive prenatal test) they are referring to the analysis of circulating free DNA in maternal blood. "We have been doing prenatal screening for chromosomal abnormalities for over 20 years, which consists of determining the risk of the 3 most common trisomies," explains the specialist. “Trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome) and trisomy 13 (Patau syndrome) seriously affect the life of the future child, with trisomy 21 having the highest prevalence in live births,” she stresses.

Since 2000, different strategies have been developed for prenatal screening of chromosomal abnormalities using biochemical and ultrasound markers, such as nuchal translucency (fluid accumulation in the nape of the neck and posterior part of the fetus’ neck). Thanks to these strategies, according to Dr. Barrenechea, it has been possible to calculate the risk of chromosomal abnormalities with a detection rate of over 90% and a false positive rate of less than 5%. Since 2011, the noninvasive prenatal test (NIPT) began to be used for screening for the most frequent chromosomal abnormalities. “In recent years, the advance of genomic technologies has allowed the introduction into clinical practice of screening strategies based on analysis of circulating free DNA, with a detection rate of over 95% for the three most common trisomies and false positive rates of 0.5%,” highlights Dr. Eva Barrenechea. 

Finally, in the coming years, greater progress and innovation are expected in the field of prenatal diagnosis, where “the use of more powerful techniques will allow more cases to be detected reliably, and screening can even be extended to other diseases,” says the speaker.