An unusual presentation of a usual disorder: Van Wyk-Grumbach syndrome.

Van Wyk-Grumbach syndrome (VWGS) is characterized by juvenile hypothyroidism, delayed bone age, and isosexual precocious puberty. A 10.7-year-old girl presented with premature menarche and isosexual precocity. She had delayed bone age and multicystic ovaries. High circulating levels of TSH with prepubertal LH confirmed the diagnosis of VWGS. Tendency to manifest sexual precocity in VWGS may be directly related to the severity of the TSH elevation. High circulating levels of TSH acting directly on FSH receptors are the actual mediators of precocity.