It has been demonstrated that the prevalence of Shypo in patients with obesity is relatively high (33), but the diagnosis of Shypo may be complex in the severely obese, particularly with body mass index ≥ 40 kg/m2 (3), since a slight increase in TSH levels (usually < 8 mU/L) can occur as a consequence of the direct stimulatory effect of leptin on the hypothalamic neurons secreting the thyrotropin stimulating hormone (34,35), which is not a true thyroid disease. This evidence concerns the gene LEP and thyroiditis.