FGF21 and thyrotoxicosis: The primary research questions in this study are a) whether there is any alteration in peripheral signals that control appetite, namely leptin and ghrelin, in thyrotoxicosis, b) whether levels of the thermogenic hormones FGF21 and leptin are altered in thyrotoxicosis, and c) what the influence of excess thyroid hormones on weight, body composition, insulin resistance, and adipokines is.