Association of maternal serum trace elements with newborn screening-thyroid stimulating hormone

Abstract Objectives Trace elements are essential in thyroid functioning as they incorporate into biologically important enzymes as cofactors. The placenta can either activate or inhibit the transfer of maternal trace elements to the unborn. An imbalance of maternal trace elements in pregnancy may affect both maternal and newborn thyroid function. Methods Blood samples from 315 lactating mothers were collected in the first 48 h after delivery and evaluated for selenium (Se), copper (Cu), manganese (Mn), and zinc (Zn) using flame atomic absorption spectroscopy (FAAS) and quadrupole inductively coupled plasma-mass spectrometer (ICP-MS). Thyroid hormones and auto-antibodies (thyroid-stimulating hormone (TSH), free T3 (fT3), free T3 (fT4), anti–thyroid peroxidase (anti-TPO), and antithyroglobulin (anti-TG)) were analyzed in maternal blood using an electro-chemiluminescence immunoassay (ECLIA). Between 48 and 72 postpartum hours, spot blood samples were used for newborn screening-TSH measurement. Correlation and multivariate analyses were performed to evaluate the effect of maternal trace element levels on newborn screening-TSH levels. Results The medians (min-max) of maternal Se (45.16 µg/L (21.28–79.04)), Cu (210.10 µg/dL (117.04–390.64)), Mn (2.11 µg/L (0.20–3.46)), and Zn (0.43 mg/L (0.24–0.66)) were determined. A positive correlation was detected between Zn and maternal TSH levels (r=0.12, p < 0.05). Newborn screening-TSH was significantly correlated with maternal Cu (r=0.14, p < 0.01). Similarly, Cu exhibited weak associations in clustering analysis while others shared common clusters with newborn-screening TSH. Conclusions There was no significant association between most of the maternal serum trace elements and maternal thyroid hormone parameters, with an only exception between maternal Zn and maternal serum TSH. Finally, the association between maternal serum Cu levels and newborn screening-TSH levels may highlight the importance of maternal Cu levels on the newborn thyroid health.