Thyroid replacement therapy in hypothyroid Desmethyl Erlotinib patients has been shown to improve their prognosis and reduce their cardiovascular risk. However, some hypothyroid patients might Ethacridine lactate monohydrate remain at an increased risk for the morbidity associated with circulatory diseases and ischemic heart disease as well as other systemic manifestations despite treatment with LT4. After 6 weeks of PTU treatment, the fT3 and fT4 levels were depressed, whereas the TSH level drastically increased, indicating the establishment of hypothyroidism. The normal levels of fT3 and fT4 following the one week treatment with LT4 confirmed the rapid reversal of hypothyroidism. Intriguingly, the levels of fT3 and fT4 rose but still remained significantly low with high TSH 6 weeks after the PTU treatment was stopped in the animals that did not receive LT4. This apparent discrepancy in the levels of thyroid hormones and TSH has been described in the literature; in fact, the usual reverse relationship between the serum levels of TSH and T4 might not be maintained in hypothyroid patients. Patients with severe or long-standing primary hypothyroidism may require three to six months of hormone replacement before the TSH levels are fully suppressed. Conversely, the serum TSH concentration may remain low or normal for up to five weeks after the withdrawal of thyroid hormone replacement when the serum levels of T4 and T3 have already declined to values well below the lower range of normal. Hypothyroidism significantly reduced body weight and elevated the plasma leptin concentration. These findings may be contradictory to the data in human subjects with thyroid disorders, where the majority of the hypothyroid patients suffer from an increased body weight. However, these findings are in agreement with previously reported data on rats ; those studies showed that, in hypothyroid rats, the body weight gain per week was very low and the body growth was strongly restricted. Additionally, the hypothyroid state was found to increase the serum leptin level; the “satiety hormone” leptin suppresses food intake in hypothyroid rats and may reduce the level of metabolism and body growth gain.