Morning cortisol as an alternative to Short Synecthan test for the diagnosis of primary adrenal insufficiency

OBJECTIVE: To determine 7-9 am serum cortisol less than 5mcg/dl is an independent reliable confirmatory test for the diagnosis of primary adrenal insufficiency (PAI). METHODS: A total of 164 patients who visited the outpatient or inpatient department of Aga Khan University Hospital from June 2011 to June 2017 were included for the study. All those patients whose levels came out less than 5mcg/dl were recruited for the study and they all underwent SST. Other demographic and laboratory data were also recorded. RESULTS: The sensitivity of morning cortisol for diagnosis of PAI is 100% if levels are <1mcg/dl and decreases to 71.88% if levels are up to 5mcg/dl. CONCLUSION: Morning cortisol is sensitive enough as an alternative to SST if levels are <1mcg/dl (100%). However, if the levels are increased from > 1mcg/dl to < 5 mcg/dl, the sensitivity decreases gradually from 98% to 71%.