Melanocyte Stimulating Hormone, Gamma (g-MSH)

Clinical Significance:
g-Melanocyte Stimulating Hormone is a 12 amino acid peptide produced from metabolism of Proopiomelanocortin.  g-Melanocyte Stimulating Hormone is not structurally related to either a- or b-Melanocyte Stimulating Hormone, but shares the same major biological function:  hyperpigmentation.  It also stimulates Aldosterone secretion, and is excreted by the placenta.  g-Melanocyte Stimulating Hormone is usually present in very low concentrations.  In cases of ectopic ACTH tumors, g-Melanocyte Stimulating Hormone is usually elevated.  Although its release is connected to the mechanisms controlling ACTH and b-Endorphin, it is not biologically or metabollically related to either.

Reference Range:
Up to  150 pg/ml

g-Melanocyte Stimulating Hormone is measured by direct radioimmunoassay.

Patient Preparation:
Patient should not be on any Steroid, ACTH, or hypertension medication, if possible, for at least 48 hours prior to collection of specimen. 

Specimen Collection:
3mL EDTA plasma should be collected and separated as soon as possible. Freeze specimen immediately after separation. Minimum specimen size is 1mL. Serum is no longer accepted for ISI’s assay.

Special Specimens:
For tumor/tissue and various fluids (i.e. CSF, peritoneal, synovial, etc.) contact the Institute for requirements and special handling.

Shipping Instructions:
Ship specimens frozen in dry ice.

1. DB Seifer and RL Collins.  Current Concepts of b-Endorphin Physiology in Female Reproductive Dysfunction.  Clinical Chemistry 54: 757-771, 1990.

2. Y Nakai, I Tanaka, J Fukata, and K Nakao, S Oki, S Takai, and H Imura.  Evidence for g-MSH-Like Immunoreactivity in Ectopic ACTH-Producing Tumors.  Journal of Clinical Endocrinology and Metabolism 50: 1147, 1980.