Gonadotrophinomas	

Gonadotrophinomas are more common than thyrotrophinomas (thyroid-stimulating hormone (TSH) producing adenomas), and are increasingly being recognised. Gonadotroph and thyrotroph cell adenomas, however, are rare and have a combined incidence of five per cent. Clinically, gonadotrophinomas are most often seen in middle-aged men who have a history of normal puberty and normal fertility (Fig. 2.5). Such patients come to medical attention because they experience visual impairment, often caused by an enormous pituitary tumour. Examination shows normal virilisation, but the testes may be larger than normal. In vivo, they most commonly secrete follicle-stimulating hormone (FSH), often accompanied by excessive production of FSH b- and a-subunits. Intact luteinising hormone (LH) is much less commonly secreted.