Assessment of thyroid function during postpartum period with total thyroxine and total triiodothyronine levels measured by LC-MS/MS

Abstract

Background: Assessment of thyroid function is important during postpartum period. However, measurements of total thyroxine (TT4) and total triiodothyronine (TT3) levels by immunoassays are mostly inaccurate during pregnancy and postpartum period, as immunoassays are interfered by hormone-binding proteins. LC-MS/MS is known to be selective and specific for the analysis of endocrine hormones and can be utilized for the analysis of TT4 and TT3. The aim of this study is to evaluate the reliability of TT4 and TT3 results measured by LC-MS/MS during postpartum period.

Materials and Methods: Serum samples (n = 358) were obtained within postnatal 48 hr from participants. TT4 and TT3 levels were measured by LC-MS/MS method (TT4_MS and TT3_MS). Levels of free T4 (FT4), free T3 (FT3) and thyroid-stimulating hormone (TSH) were measured by immunoassay methods (FT3_IA, FT4_IA, and TSH_IA).

Results: Statistically significant correlation was found between TSH_IA and TT4_MS (r = −0.13 and P = 0.01), whereas no correlation was detected between TSH_IA and FT4_IA, TT3_MS or FT3_IA.

Conclusions: Significant negative correlation between TT4_MS and TSH_IA, and lack of correlation between FT4_IA and TSH_IA indicates that TT4_MS measured by LC-MS/MS could be a more reliable parameter in the diagnosis of thyroid deficiency during postpartum period.

Graphical Abstract

Keywords:

• LC-MS/MS
• postpartum period
• total thyroxine
• total triiodothyronine

Disclosure statement

The authors declare that they have no conflict of interest.