Corticotropin Releasing Factor is a 41 amino acid peptide produced in the hypothalamus. It stimulates the release of ACTH from the pituitary which in turn releases Cortisol from the adrenal gland. The Cortisol produced rapidly shuts off CRF secretion acting as a negative feedback control. CRF also releases b-Endorphin, b-Lipotropin and other related proopiomelanocortin peptides. Ectopic tumors producing ACTH also frequently produce CRF. In these patients ACTH usually does not respond to Dexamethasone suppression. CRF is markedly elevated in third trimester pregnancy. Most of it is produced by the placenta and is bound to CRF-Binding Protein and is biologically inactive. The CRF stimulation test is the most effective method of differentiating primary from secondary adrenal insufficiency and in differentiating hypothalamic from pituitary causes.
Up to 10 pg/ml
Corticotropin Releasing Factor is measured by direct radioimmunoassay.
Patient should be fasting 10 – 12 hours and should not be on any corticosteroid, ACTH, or estrogen medications, if possible, for at least 48 hours prior to collection of specimen. An am specimen is preferred.
3 ml EDTA plasma should be collected and separated as soon as possible. Plasma should be frozen immediately after separation. Minimum specimen size is 1 ml.
For tumor/tissue and various fluids (i.e. CSF, peritoneal, synovial, etc.), contact the Institute for requirements and special handling.
Ship specimens frozen in dry ice.
1. Jones SA, Brooks AN, and Challis JRG. Steroids Modulate Corticotropin-Releasing Hormone Production in Human Fetal Membranes and Placenta. J Clin Endocrinol and Metab 68: 825-830, 1989
2. Vigh S, Merchenthaler I, Torre-Aleman I, et al. Corticotropin Releasing Factor (CRF): Immunocytochemical Localization and Radioimmunoassay (RIA). Life Sci 31: 2441, 1982.