Valores de referencia de hormonas tiroideas en la población de gestantes en Lugo

Abstract

Background and objectiveThe complex physiology of thyroid function during pregnancy requires a hormonal evaluation according to reference values for each trimester, each area, and with the techniques of each laboratory. The objectives of this study were to analyse thyroid function in the three trimesters of pregnancy and to establish the reference values of hormones in pregnant women in this health area (Lugo). MethodsA total of 831 pregnant women were included in the study (median age: 33years, age range: 16-47years). Once the exclusion criteria were applied, the sample consisted of 641 pregnant women, a size that can be considered representative of the reference population. ResultsThe reference intervals were as follows: TSH first trimester, 0.10-3.74mIU/L; second trimester, 0.45-3.77mIU/L; and third trimester, 0.36-4.15mIU/L. For Free T4 in the first trimester, 0.87-1.34ng/dL; second trimester, 0.78-1.20ng/dL; and third trimester, 0.78-1.23ng/dL. For Free T3 in the first trimester, 2.52-3.78pg/mL; second trimester, 2.22-3.21pg/mL; and third trimester, 2.17-3.14pg/mL. The presence of thyroid autoimmunity was confirmed in 109 women (13.1%), who presented with higher TSH values than pregnant women without thyroid autoimmunity. ConclusionThe reference intervals for TSH, Free T4, and Free T3 obtained in this study are below those used in the non-pregnant adult population in this laboratory. This should help to identify more accurately a possible thyroid dysfunction in pregnant women in the study area, avoiding an underdiagnosis of subclinical hypothyroidism and reducing the possible associated perinatal complications.