Serum concentrations and trimester-specific intervals for TSH and fT4 duringthe last trimester of pregnancy
General Medicine, 2023, 25(4), 18-24.
B. Delev1,2, T. Deneva1,2,3, B. Nonchev4, K. Kilova5
1 Department of Clinical Laboratory, Farmacy Faculty, Medical University ‒ Plovdiv
2 University Hospital St. George ‒ Plovdiv
3 Research institute at Medical University ‒ Plovdiv
4 Department of Endocrinology, Medicine Faculty, Medical University ‒ Plovdiv
5 Department “Medical Informatics, Biostatistics and E-learning”, Faculty of Public Health, Medical University – Plovdiv
Abstract. Disorders in the functioning of the thyroid gland are among the most common endocrine diseases during pregnancy. The main diagnostic indicator for the evaluation of thyroid diseases is the measurement of serum levels of thyroid-stimulating hormone and free thyroxine, and according to the American Thyroid Association (ATA) and the European Thyroid Association (ETA), the optimal approach for interpreting the results is the development and application of population-based reference intervals. The aim of the study to develop population-specific reference limits of TSH and fT4 for third trimesters of pregnancy. Materials and Methods: To develop reference limits, 120 pregnant women over the age of 18 were observed. Serum concentrations of TSH and fT4 were determined by immunoassay method using automatic system (Access 2, Beckman Coulter). To determine the limits of the reference intervals, we have applied the parametric method. Data analysis was performed using IBM SPSS 26 and REFVAL 4.11. Results: Our results show that reference intervals for TSH and fT4 for third trimesters are different from the interval accepted for the non-pregnant population. In conclusion the data from our study could be the basis for assessing the individual risk of gestational thyroid disorders and their administration would be more sensitive to detect thyroid dysfunction in this period.
Key words: pregnancy, TSH, fT4, reference interval, thyroid dysfunction
Address for correspondence: Boyan Delev, MD, e-mail: boyan.delev@mu-plovdiv.bg