Endocrine Abstracts

Ferritin is a universal intracellular protein that acts as an iron carrier. Several studies have indicated that iron deficiency affects thyroid function in non-pregnant women. Our objective was to assess the relationship between serum ferritin levels and thyroid function along with thyroid autoimmunity in pregnant women during the second trimester. 1592 pregnant women were recruited from the obstetric outpatient department during the second trimester. Serum ferritin (SF) levels, thyroid function, TPOAb and TGAb were determined by electrochemiluminescence immunoassay. Age, BMI and pregnant week were recorded. Iron deficiency (ID) was defined as ferritin <12 μg/L, and subclinical hypothyroidism (SCH) when TSH was >4 mIU/L. The percentage of ID and SCH were 11.87%, 9.17% respectively. Serum FT4 levels were significantly lower in the ID group as compared with the non-ID group [13.82(8.91–25.04) vs 14.60 (8.22–47.24) mIU/L; P=0.000],TSH levels were similar in the ID and non-ID group [1.78(0.01-7.13) vs 1.71 (0.01–10.2) pmol/L; P=0.520] and The prevalence of abnormal elevated TPOAb and/or TGAb, and SCH were comparable between both groups. SF levels were negatively correlated with serum TSH levels (r=−0.112, P=0.000), and positively correlated with FT4 levels (r=0.201, P=0.000). Linear regression analysis showed SF, age, week of gestation were significant predictors of regression with TSH as the dependent variable (β:−0.002, −0.026, and 0.061 respectively; all P<0.05), or with FT4 as the dependent variable (β: 0.005, −0.054, and −0.24 respectively; all P<0.05). Interestingly, in the logistic regression model, ID remained associated with abnormal elevated TGAb after correction for confounding factors [OR=2.84, 95%CI (1.385, 5.825), P=0.004], but not correlated with abnormal elevated TPOAb. Therefore, maternal ID was a determinant of higher serum TSH, lower FT4 levels, and abnormal elevated TGAb in pregnant women during the second trimester.