Clinical case seminar - Reduced growth hormone receptor messenger ribonucleic acid in an aged man with chronic malnutrition and growth hormone resistance

A severely malnourished 87-yr-old man presented with hypoglycemia. Serum GH levels were elevated, and serum levels of insulin-like growth factor I (IG F-I), IGF-binding protein-3, and GH-binding protein were extremely reduced. The patient's GH was biologically active. Administration of GH for 4 conse cutive days resulted in a slight increment in serum IGF-I levels, but no el evation of serum IGF-binding protein-3. The expression of GH receptor messe nger ribonucleic acid in the liver was greatly reduced. An autopsy revealed a Rathke's cleft cyst confined to the sella turcica. Immunohistochemical s tudies for GH showed that there was nothing to suggest a tumor overproducin g GH. In addition, TSH levels were elevated in the presence of normal thyro id hormone levels, and there was a cluster of cells showing strong immunohi stochemical staining for the TSH beta-subunit in the pituitary. In this pat ient, the decreased expression of GH receptor messenger ribonucleic acid in the liver may have been responsible for the GH resistance, which was proba bly caused by malnutrition.