Endocrine Abstracts

Introduction: Limited data is available on the natural history of thyroid disorders in the Middle East. We aim to report the rate of progression of subclinical hypothyroidism to overt hypothyroidism specifically for the UAE population.

Methods: Retrospective analysis was performed on all patients attending Imperial College London Diabetes Centres in the UAE over ten years from 2007 to 2017, with a diagnosis of spontaneous subclinical hypothyroidism (TSH >4.2 and <10 μIU/ml) without thyroid replacement. Categorical variable analysis and logistic regression analysis were used to identify factors associated with increased risk of conversion to overt hypothyroidism including gender, BMI, baseline TSH, diabetes status and thyroid peroxidase antibody (TPO) positivity status.

Results: 12,900 patients with subclininical hypothyroidism during the study period were identified. 847 (6.5%) of patients developed overt hypothyroidism, defined as TSH >10 μIU/ml. The mean time to development of overt hypothyroidism was 90 weeks. The majority of the patients with overt hypothyroidism were female (67.7%). 44.7% of all patients with overt hypothyroidism had diabetes and 42.8% were obese (BMI ≥30 kg/m²). In those who developed overt hypothyroidism, TPO antibodies were positive in 53%. Logistic regression analysis showed that female gender (P<0.03) and higher baseline TSH (TSH ≥6 μIU/ml; P<0.02) were both associated with increased risk of progression to overt hypothyroidism. TSH levels spontaneously normalized without treatment in 41.9% of patients (mean time of 8.5 weeks).

Conclusion: Rate of progression to overt hypothyroidism in our population is 6.5% over 10 years. In keeping with studies in other populations females and those with higher baseline TSH are more likely to develop overt hypothyroidism. Further studies are required to investigate and identify other clinical and biochemical predictors that could be associated with development of overt hypothyroidism in the UAE population.