Recombinant human TSH acutely impairs endothelium dependent vasodilation

We read with interest the review article by Duntas & Biondi dealing with clinical and quality of life consequences induced by short-term hypothyroidism (1). Withdrawal of levothyroxine therapy exacerbates neuropsychiatric symptoms and increases cardiovascular risk, although these effects are usually reversible restoring a condition of stable euthyroidism (1). Shortterm hypothyroidism is associated with cardiac abnormalities, increased peripheral vascular resistance, and endothelium dysfunction. In this setting, the recent use of recombinant human thyrotropin (rhTSH) in the clinical practice of thyroid carcinoma represents a valid alternative to levothyroxine withdrawal. The authors state that rhTSH administration is not accompanied by significant cardiac alterations and induces beneficial effects on the vascular system by increasing circulating nitric oxide (2).