Corticotropin- and growth hormone-releasing factor (CRF and GRF) in the diagnosis of hypothalamo-pituitary diseases.

The recently discovered releasing factors for ACTH and growth hormone, CRF and GRF, have stimulated our understanding of the hypothalamo-pituitary physiology and pathophysiology. Whereas CRF, a 41 amino-acid residue peptide, seems to be a useful additional tool in the differential diagnosis of Cushing's syndrome, GRF, a 44 amino-acid residue peptide, seems to be of little value in the diagnosis of active acromegaly. However, both releasing factors are useful in the follow-up of these two hypersecretory diseases after neurosurgical treatment. In addition, the measurement of CRF and GRF activity by radioimmunoassay in the peripheral circulation will be of great importance in making the diagnosis of ectopic CRF- and GRF-secretion, syndromes which have been appreciated only in recent years. Furthermore, CRF and GRF-stimulation tests are useful in elucidating the cause of anterior pituitary failure and GRF may be of benefit for the treatment of pituitary dwarfism. However, it has to be stressed that the results of the new CRF and GRF tests can only be interpreted together with results of other established pituitary function tests and the neuroradiological evaluation of the hypothalamo-pituitary area.