Prevalence and risk factors for hypothyroidism in Jordanian women: comparison between different reference ranges.

The aim of this cross-sectional study in Jordan was to estimate the prevalence of hypothyroidism among women during early pregnancy and to assess the association of risk factors with hypothyroidism. According to internationally adopted thyroid stimulating hormone (TSH) and thyroxine (T4) pregnancy reference ranges (TSH > or = 2.6 mlU/L and T4 10.6-20.4 pmol/L), 67 of 322 (20.8%) women were diagnosed with sub-clinical hypothyroidism. When the general laboratory criteria were applied (TSH > or = 4.6 mlU/L and T4 < 10.6 pmol/L) the prevalence dropped to 4.3%. No cases of overt hypothyroidism were diagnosed using either diagnostic criterion. Younger age and being in gestational weeks 1-8 were significant risk factors for hypothyroidism. It is suggested that the reference criteria need revision, and that pathology laboratories should adopt appropriate pregnancy-specific reference intervals.