INTRODUCTIONSubclinical hypothyroidism is a state of mild thyroid failure and is essentially a laboratory diagnosis with elevated serum thyroid stimulating hormone (TSH) and a normal free thyroxine (FT4) concentration.1 Subclinical hypothyroidism is much more common than overt hypothyroidism and hence the early diagnosis and treatment of the condition may prevent the onset of overt hypothyroidism and its associated effects.2 Patients with subclinical hypothyroidism with high titre of antithyroperoxidase (anti-TPO) antibodies are more likely to progress to overt hypothyroidism. Most of the hypothyroid patients have an elevated anti-TPO titre, suggesting an autoimmune etiology for hypothyroidism. Literature evidence substantiates the positive association between serum anti-TPO levels and the activity of chronic autoimmune thyroiditis. ABSTRACTBackground: Subclinical hypothyroidism is a state of mild thyroid failure and is essentially a laboratory diagnosis with elevated serum thyroid stimulating hormone (TSH) and a normal free thyroxine (FT4) concentration. The main objective of study is to evaluate the prevalence of anti-thyroid peroxidise (anti-TPO) antibodies among patients with clinical and subclinical hypothyroidism. Methods: A prospective study was conducted involving 50 patients with biochemical evidence of hypothyroidism. Subclinical hypothyroidism was defined as thyroid stimulating hormone (TSH) >5.0 µIU/ml with normal FT4 and clinical hypothyroidism as free thyroxine (FT4) and high TSH. A detailed history, clinical examination, and investigations comprising of complete haemogram, fasting plasma glucose, fasting FT4, TSH, anti-TPO antibodies and lipid profile were done for all the patients. Results: Out of 50 cases, 28 subjects had clinical hypothyroidism (25 females and 3 males) and 22 had subclinical hypothyroidism (14 females and 8males). Among the 50 subjects with clinical and subclinical hypothyroidism, 33 were anti-TPO positive. The corresponding percentage of anti-TPO positivity noted in the clinical hypothyroidism and subclinical hypothyroidism groups were 80 % and 50% respectively. Conclusions: Serum TSH and anti-TPO analyses are essential in determining the etiology of hypothyroidism and risk of progression to overt hypothyroidism in patients with subclinical.

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