Hypothyroidism and obesity. Cause or effect?

OBJECTIVE To establish relationship between obesity and hypothyroidism and to analyze the frequency the frequency of primary hypothyroidism in obese patients and frequency of obesity in primary hypothyroidism patients. METHODS We conducted this retrospective, observational study in the Department of Endocrinology and Obesity Clinic, Medwin Hospital, Hyderabad, India in Mar 2008. In the last 18 months (between September 2006 to February 2008), data on 625 consecutive primary hypothyroidism patients (Group I) and 450 patients from obesity clinic (Group II) were analyzed. Frequency difference between the 2 groups was assessed by Chi-square test. RESULTS In Group I, 278/625 (44%) had body mass index (BMI) >25 kg/m2. Obesity was higher (46% versus 34%) in overt hypothyroidism than in subclinical hypothyroidism (p=0.21). More patients were overweight in overt hypothyroidism group than in subclinical hypothyroidism group (p=0.02). In obesity patients, overt hypothyroidism was present in 33% and subclinical hypothyroidism in 11% patients. CONCLUSION Overall thyroid dysfunction was found more in obese individuals with varying degree of significance. Detailed studies are required to assess the cause and effect relation between obesity and hypothyroidism.