[Transient neonatal hyperthyroidism in the child of a treated hyperthyroid mother. Subsequent appearance of sexual precocity].

We report a newborn female with neonatal hyperthyroidism, born to a mother with Graves disease treated with potassium iodide and carbimazole. At four months she had some breast development, a bone age advance of one year, and elevated levels of FSH and estradiol. Later on the prolactin level was also raised, while LH and TSH values continued low. Posteriorly, irregular cutaneous pigmentation, brown in colour, was evident on the neck and trunk, and a McCune-Albright syndrome was suspected. The relationship between these conditions and treatment of them is discussed.