PRIMARY HYPOTHYROIDISM WITH HYPERPROLACTINEMIA AND PITUITARY ENLARGEMENT MIMICKING A PITUITARY MACROADENOMA

Hyperprolactinaemia can occur in patients with hypothyroidism. A 32-ye ar-old woman with primary hypothyroidism presented with amenorrhoea an d galactorrhoea of two years' duration, She had hyperprolactinaemia, l ow basal morning cortisol levels and evidence of a pituitary macroaden oma on magnetic resonance imaging, Therapy with L-thyroxine resulted i n induction of regular menses, resolution of galactorrhoea, normalisat ion of hormone levels and disappearance of the image of pituitary macr oadenoma, It seems that enlargement of the pituitary due to thyrotroph and/or lactotroph cell hyperplasia secondary to hypothyroidism is res ponsible for this 'pseudotumour' image on radiological study, Recovery of her low basal cortisol values during treatment could also be expla ined by the dissolution of the pressure effect of enlarged pituitary i n addition to the regression of hypothyroidism, In subjects with prima ry hypothyroidism and hyperprolactinaemia and pituitary enlargement, t hyroid hormone replacement should be a first line treatment preceding pituitary surgery and bromocriptine use.