An unusual case of precocious puberty and macroorchidism

The role of thyroid hormone in pubertal development is complex, with majority of the hypothyroid patients failing to attain puberty. However, isosexual precocious puberty with delayed bone age has been described in female hypothyroid patients, and is called Van Wyk Grumbach Syndrome (VWGS). The presentation of VWGS in boys is different, with the major presentation being isolated enlargement of the testes, with no signs of virilisation. The cross over action of Thyroid Stimulating Hormone (TSH) on Follicle Stimulating Hormone (FSH) receptor producing Sertoli cell hyperplasia produces testicular enlargement, and lack of action of TSH on Luteinizing hormone (LH) with no Leydig cell hyperplasia explaining lack of virilisation. Delayed bone age and typical features of hypothyroidism help to differentiate this condition from other causes of precocious puberty.