Abstract #1403717: Thyro-Adrenal Insufficiency in Severe Hypothyroidism – A Clinical Mirage? A Cross-Sectional, Propensity-Matched Case-Control Study from a Tertiary Care Centre Kalaburgi, Kalyana Karnataka

Abstract

Assessment of 8:00 AM cortisol levels and predict risk of adrenal insufficiency in treatment naïve severe hypothyroidism. A cross-sectional, observational, case-control study was conducted at tertiary care teaching hospital in Kalaburagi, Kalyana Karnataka, South India between January 2017 and March 2020. We included 71 consecutive adult individuals in the age group of 18-50 years of either gender, referred to the Division of Diabetes and Endocrinology, Department of Internal Medicine. All the cases were treatment naïve, diagnosed with severe hypothyroidism defined as TSH levels > 100 μIU/ml. We excluded patients with a past history of Grave’s disease, those who had ever used anti-thyroid drugs, those who had taken radioactive iodine, received steroids for any reasons, patients with a history of thyroidectomy, pre-existing pituitary or adrenal disorders, pregnancy, patients on oral contraceptives and patients with any underlying malignancies. The control population included individuals without any known thyroid disorder or any other comorbid conditions that are known to affect the function of hypothalmo-pituitary-adrenal axis. The controls were age and gender-matched. We used SAS 9.4 version software to analyze the data. T3, T4, and cortisol have been categorized and summarized descriptively with the actual collected values. Continuous variables are presented with mean and standard deviation. Categorical parameters are summarized with counts and percentages. Correlation coefficients among the T3, T4, and cortisol were generated for the overall population. Seventy-one cases of severe hypothyroidism (TSH >100 mIU/L) were compared with age and gender-matched controls (n=40). The mean age of the patients was 30.0±9.0 years and 88.7% were females. Serum cortisol levels were significantly lower in cases than in controls (8.6±4.2 vs. 16.0±2.22 μg/dl respectively, p<0.0001). Six (8.5%) cases were identified with adrenal insufficiency. After propensity matching, T3 (20.32±16.94 vs. 39.33±38.92 ng/dl, p=0.018) and T4 (0.81±0.55 vs. 1.93±1.17 μg/dl, p=0.005) levels were comparatively lower in adrenal insufficiency cases than those without adrenal insufficiency. Serum T3 (r = -0.243, p=0.041) but not T4 (r = -0.103, p=0.391) had a significant negative correlation with serum cortisol levels. Transient adrenal insufficiency can be seen in treatment naïve severe hypothyroidism. In our cohort, the incidence of adrenal insufficiency was 8.5%. An apt clinical vigilance is needed to identify adrenal insufficiency in such patients. Further studies are needed to understand the implications of severe hypothyroidism with adrenal insufficiency. A short synaecthien test may be needed in with low cortisol at diagnosis of severe hypothyroidism.