BACKGROUND: The short synacthen test (SST) is used to investigate patients with suspected hypothalamus-pituitary-adrenal (HPA) axis pathology. A rise of serum total cortisol (total cortisol) above 550 nmol/L is accepted as sufficient adrenal reserve. In total, 80% of cortisol is bound to cortisol-binding globulin (CBG) and 10% to albumin. In the acute phase responses CBG concentrations decrease and can influence the interpretation of SST. The free cortisol index (FCI) is a surrogate marker for free cortisol and is defined as total cortisol (nmol/L)/CBG (mg/L) with an FCI > 12 representing sufficient adrenal reserve. The aim of this study was to compare total cortisol and FCI in the interpretation of SST in patients with liver impairment. METHOD: SST was done on 26 patients with liver impairment. Total cortisol was measured on Advia Centaur; serum CBG by radioimmunoassay and FCI calculated. RESULTS: Eleven (42%) patients had a total cortisol >550 nmol/L (range 555-2070) and FCI > 12 (12.0-68.9) suggesting sufficient cortisol reserve. Three patients (13%) had total cortisol <550 nmol/L (268-413) and FCI < 12 (3.5-11.6) consistent with cortisol deficiency. Twelve patients (46%) had a total cortisol <550 nmol/L (144-529), but an FCI > 12 (12.0-52.9). None of the patients had a total cortisol >550 nmol/L and FCI < 12. CONCLUSION: When total cortisol alone is used to interpret SST in patients with liver impairment, 46% may have been classified as having adrenal insufficiency because of low CBG. FCI may be better for the evaluation of HPA axis insufficiency in patients with liver impairment.
BACKGROUND: The short synacthen test (SST) is used to investigate patients with suspected hypothalamus-pituitary-adrenal (HPA) axis pathology. A rise of serum total cortisol (total cortisol) above 550 nmol/L is accepted as sufficient adrenal reserve. In total, 80% of cortisol is bound to cortisol-binding globulin (CBG) and 10% to albumin. In the acute phase responses CBG concentrations decrease and can influence the interpretation of SST. The free cortisol index (FCI) is a surrogate marker for free cortisol and is defined as total cortisol (nmol/L)/CBG (mg/L) with an FCI > 12 representing sufficient adrenal reserve. The aim of this study was to compare total cortisol and FCI in the interpretation of SST in patients with liver impairment. METHOD: SST was done on 26 patients with liver impairment. Total cortisol was measured on Advia Centaur; serum CBG by radioimmunoassay and FCI calculated. RESULTS: Eleven (42%) patients had a total cortisol >550 nmol/L (range 555-2070) and FCI > 12 (12.0-68.9) suggesting sufficient cortisol reserve. Three patients (13%) had total cortisol <550 nmol/L (268-413) and FCI < 12 (3.5-11.6) consistent with cortisol deficiency. Twelve patients (46%) had a total cortisol <550 nmol/L (144-529), but an FCI > 12 (12.0-52.9). None of the patients had a total cortisol >550 nmol/L and FCI < 12. CONCLUSION: When total cortisol alone is used to interpret SST in patients with liver impairment, 46% may have been classified as having adrenal insufficiency because of low CBG. FCI may be better for the evaluation of HPA axis insufficiency in patients with liver impairment.
Authors: Laura E Dichtel; Melanie Schorr; Claudia Loures de Assis; Elizabeth M Rao; Jessica K Sims; Kathleen E Corey; Puja Kohli; Patrick M Sluss; Michael J McPhaul; Karen K Miller Journal: J Clin Endocrinol Metab Date: 2019-10-01 Impact factor: 5.958
Authors: Derek D Cyr; Joseph E Lucas; J Will Thompson; Keyur Patel; Paul J Clark; Alexander Thompson; Hans L Tillmann; John G McHutchison; M Arthur Moseley; Jeanette J McCarthy Journal: PLoS One Date: 2011-07-05 Impact factor: 3.240
Authors: Stefan R Bornstein; Bruno Allolio; Wiebke Arlt; Andreas Barthel; Andrew Don-Wauchope; Gary D Hammer; Eystein S Husebye; Deborah P Merke; M Hassan Murad; Constantine A Stratakis; David J Torpy Journal: J Clin Endocrinol Metab Date: 2016-01-13 Impact factor: 5.958