Differences and associations of metabolic and vitamin D status among patients with and without sub-clinical hypothyroid dysfunction

Background: Sub-clinical hypothyroid dysfunction, a relatively understudied disorder in the Kingdom of Saudi Arabia (KSA), has significant clinical implications if not properly monitored. Also from KSA, more than 50% of the population suffer from hypovitaminosis D (<50 nmol/l). In this cross-sectional case-control study, we described the differences and associations in the metabolic patterns of adult Saudis with and without hypothyroid dysfunction in relation to their vitamin D status, PTH, calcium and lipid profile. Methods: A total of 94 consenting adult Saudis [52 controls (without subclinical hypothyroidism), 42 cases (previously diagnosed subjects)] were included in this cross-sectional study. Anthropometrics were obtained and fasting blood samples were taken for ascertaining lipid and thyroid profile, as well as measuring PTH, 25(OH) vitamin D and calcium. Results: Cases had a significantly higher body mass index than the controls (p < 0.001). Circulating triglycerides was also significantly higher in cases than the controls (p = 0.001). A significant positive association between HDL-cholesterol and PTH (R = 0.56; p = 0.001), as well as a negative and modestly significant negative association between LDL-cholesterol and PTH (R = - 20.0; p = 0.04) were observed. FT3 was inversely associated with circulating 25 (OH) vitamin D (R = -0.25; p = 0.01). Conclusions: Patients with hypothyroid dysfunction possess several cardiometabolic risk factors that include obesity and dyslipidemia. The association between PTH and cholesterol levels as well as the inverse association between vitamin D status and FT3 needs to be reassessed prospectively on a larger scale to confirm these findings.