A case of isolated TSH deficiency presenting as infertility.

We report a case of late-onset isolated thyroid stimulating hormone deficiency in a woman who presented with oligomenorrhoea and secondary hyperprolactinaemia. Hypothalamic and pituitary radiology and function was otherwise normal. The underlying aetiology of this condition is thought to be due to an inborn defect in the thyrotroph and treatment is with standard thyroid replacement therapy.