High normal TSH is associated with lower mannan-binding lectin in women of childbearing age

Malgorzata Karbownik-Lewinska,Adrian Krygier,Andrzej Lewinski,Magdalena Marcinkowska,Jan Stepniak

doi:10.1186/s12902-019-0484-y

Malgorzata Karbownik-Lewinska, Adrian Krygier + Show 3 more

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https://doi.org/10.1186/s12902-019-0484-y

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Abstract

BackgroundMannan-binding lectin (MBL) is a main component of the lectin pathway of the complement system. Lower MBL levels are associated with, among other conditions, hypothyroidism and adverse pregnancy outcomes. In turn, adverse pregnancy outcomes and infertility may result from hypothyroidism, even in patients with high normal Thyroid-stimulating hormone (TSH). The aim of this study was to determine if MBL level differs between women of reproductive age with low normal (< 2.5 mIU/l) and high normal (≥2.5 mIU/l) TSH. Associations with other parameters potentially affected by hypothyroidism were also evaluated.MethodsNinety five (95) patients with normal thyroid tests (TSH 0.27–4.2 mIU/l), aged 18–48 years, were prospectively enrolled. Several laboratory parameters were measured, including MBL level, thyroid tests and lipid profile.ResultsSerum MBL level was lower in women with TSH ≥ 2.5 mIU/l than with TSH < 2.5 mIU/l. This association was confirmed by univariate regression analysis. MBL level was significantly lower in patients with abnormally low HDLC/cholesterol ratio and a positive correlation was found between MBL level and HDL/cholesterol ratio.ConclusionIn women of reproductive age with normal thyroid tests, lower MBL is associated with high normal TSH and with less favourable lipid profile. Therefore treatment with L-thyroxine should be considered in women of reproductive age with TSH ≥ 2.5 mIU/l.

Highlights

Mannan-binding lectin (MBL) is a main component of the lectin pathway of the complement system
The patients were divided into two groups of seventy (70) patients with low normal Thyroid-stimulating hormone (TSH) (< 2.5 mIU/l) (Controls), and twenty five (25) patients (26.3% of the whole sample examined) with high normal TSH (≥2.5 mIU/l), which were well matched at baseline in terms of age and body mass index (BMI) (Table 1)
Parameters measured in blood serum Apart from hormones (TSH, Free thyroxine (FT4), Free triiodothyronine (FT3)), thyroid antibodies (i.e. thyroid peroxidase antibodies (TPOAb), thyroglobulin antibodies (TgAb) and thyrotropin receptor antibodies (TSHRAb)), among other laboratory parameters (such as total cholesterol, high-density lipoprotein cholesterol (HDLC), low-density lipoprotein cholesterol (LDLC), HDLC/cholesterol ratio, triglycerides (TGs), glucose, C-reactive protein (CRP), iron), and Clinical/laboratory parameters TSH < 2.5 mIU/l TSH ≥ 2.5 mIU/l p n = 70 n = 25

Summary

Introduction

Mannan-binding lectin (MBL) is a main component of the lectin pathway of the complement system. Lower MBL levels are associated with, among other conditions, hypothyroidism and adverse pregnancy outcomes. Adverse pregnancy outcomes and infertility may result from hypothyroidism, even in patients with high normal Thyroid-stimulating hormone (TSH). Mannan-binding lectin (MBL, referred to as mannose-binding lectin) is a main component of the lectin pathway of the complement system which plays a crucial role in the immune response. Taking into account the above relationship it is worth noting that hypothyroidism causes infertility and contributes to adverse pregnancy outcomes. This outcome has been repeatedly documented in human as well as in experimental studies [8].

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