Pituitary function tests in the elderly: are hypothalamic releasing factors the investigation of choice?

The use of the new hypothalamic releasing factors corticotrophin releasing factor (CRF) and growth hormone releasing factor (GHRH) has been proposed as a potential replacement for the insulin stress test in the investigation of pituitary function. The response to the injection of 100 micrograms of each compound was studied in nine elderly in-patient subjects. In response to GHRH, only four subjects demonstrated a rise in growth hormone; in response to CRF, only one subject showed a rise in cortisol. In the patients studied the combined GHRH and CRF test did not cause any cortisol or GH response in the majority.