Test Overview
Test Methodology

Direct Radioimmunoassay

Test Usage

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.

Reference Range *

Up to 10 pg/mL

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Test Details
Soft Order Code
  • Corticotropin Releasing Hormone (CRH)
Reference Laboratory
Mayo Wild 71 (ZW71) (Interscience)
Special Testing
Specimen Requirements

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. Collect specimen in a lavender top tube, aliquot plasma into a plastic vial and freeze immediately.

Special Handling

Fasting specimen. Centrifuge, aliquot and freeze immediately after collection.

Normal Volume
3 mL EDTA plasma
Minimum Volume
1 mL EDTA plasma
Additional Information

Test sent to Mayo Medical Laboratories; perfomed by Interscience Institute.

CPT Code