PUBMED:
http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmedMEDSCAPE (you have to sign up but it's free):
http://www.medscape.com/medscapetodayCECIL'S Medical Textbook chapter on adrenals is excellent!:
http://www.goodhormonehealth.com/adrenal-cecils.pdf Page 606 discusses the ACTH stim test results specifically
Here is an excellent portion of an article that discusses the ACTH stim tests (you will need to sign into MedScape to gain access):
http://www.medscape.com/viewarticle/565766_6I too had a blunted response to the ACTH stim test. Here is an excerpt from the paper (and complete references at the bottom) I wrote to get myself diagnosed:
ACTH Stimulation Test
The ACTH stimulation test was done on July 2, 2001(Appendix C, p 38-40-Test Results) because my baseline cortisol level was 8 ug/dL (range of 6-23 ug/dL) (Appendix C, p 41-Test Results) . The 250 mcg Synacthen test with a baseline measurement of ACTH and 30 and 60-minute measurements of cortisol was the test was performed. Please note: AURP recommends testing baseline cortisol, 30-minute cortisol and 60 minute cortisol. My results to this test have been interpreted as normal and borderline abnormal. AURP ACTH testing guidelines are in Appendix D, p 51-Lab Test Protocol.
“The ACTH stimulation test examines adrenal responsiveness but may not examine the entire hypothalamic-pituitary-adrenal (HPA) axis…” The ACTH stimulation test may not be reliable for assessing hypothalamic-pituitary disease, however, it can be a strong indicator of a problem with the HPA axis depending upon which cut-off level is used for the 30 minute reading. This was determined in a study where 30 patients with known hypothalamic or pituitary disease were given the insulin hypoglycemia test and the ACTH stimulation test. A cut off 550 nmol/L for the ACTH stimulation test was only a 70% indicator of hypothalamic-pituitary disorders. At 30 minutes, my response to the ACTH stimulation test was 433 nmol/L, well below the 550 nmol/L cut-off used in this test. “The short Synacthen may be misleading if used as a screening test…”
In “Defining the normal cortisol response to the short Synacthen test: implications for the investigation of hypothalamic-pituitary disorders” in Clinical Endocrinology (Oxf) a normal cortisol response at 30 minutes was a cortisol range of 510 to 626 nmol/L (18.5-22.7 ug/dL) for men and women. In addition, cortisol responses were gender dependent with females showing significantly higher responses regardless of the basal cortisol values . My response was 433 nmol/L, which is nearly 20% below the low end of the normal range (which was not gender correlated) as determined in this study. My cortisol response to exogenous ACTH stimulation was not normal and was worthy of follow up testing.
My ACTH stimulation test result of 433 nmol/L is abnormal as defined by recent medical literature. Abnormal cortisol rise during exogenous ACTH stimulation is indicative of adrenal hypofunction or problems further up the HPA axis. “It is suggested that partial ACTH deficiency may prevent involution of the adrenal cortex and preserve the cortisol response to ACTH stimulation. ” The adrenal hypofunction could have been caused by decreased stimulation of the adrenals by ACTH for an extended period of time. I say this because my ACTH level was 4 pg/mL (range 6-58 pg/mL) the one time it was tested (Appendix C, p 40-Test Results). Lack of ACTH production indicates a problem with either the hypothalamus or pituitary. The ACTH stimulation test is not a reliable indicator of hypothalamic-pituitary problems because the adrenals can still function normally and give results in the ‘normal’ range despite the fact that they are not able to function normally without exogenous stimulation .
Fiad, TM, et al., “The overnight single dose-metyrapone test is a simple and reliable index of the hypothalamic-pituitary-adrenal axis,” Clinical Endocrinology (Oxf), 1994 Nov;40 (5):603-609.
Orem, SM, et al., “Comparison of tests of stress-released cortisol secretion in pituitary disease,” Clinical Endocrinology (Oxf), 1997 May;46(5):643-644
Clark, et al., “Defining the normal cortisol response to the short Synacthen test: implications for the investigation of hypothalamic-pituitary disorders,” Clinical Endocrinology (Oxf), 1998 Sep;49(3):287-292.
Soule, SG, et al., “Failure of the short ACTH test to unequivocally diagnose long-standing symptomatic secondary hypoadrenalism,” Clinical Endocrinology (Oxf), 1996 Feb;44(2):137-40.
Greenspan, FS and Forsham, PH, Basic & Clinical Endocrinology (Los Altos, CA: LANGE Medical Publications, 1983) p. 277
Berkow, Robert, et al., p. 700.