Table 2.

Basal and cosyntropin-stimulated serum cortisol concentrations as a function of the presence of a normal or abnormal result during SST, and mean follow-up of the patients in each subgroup

	Normal responses at both times (n=307)	Confirmed primary AI (n=18)	Confirmed secondary AI (n=45)
Basal ACTH (pmol/L)	4 (1–43)	6 (1–71)*	3 (1–11)
Basal SC (nmol/L)	386±166	165±110	138±83
SC at 30 min (nmol/L)	662±193	248±110	276±110
SC at 60 min (nmol/L)	745±221	304±138	304±110
Follow-up (months)	37±17	43±18	36±15

From the whole sample, ACTH measurements were available for 342 samples.

Data are presented as mean±SD or median (minimum–maximum) as appropriate. To convert SC to metric units, multiply nmol/L by 0.03625 (results in μg/dL). To convert ACTH to metric units, multiply pmol/L by 4.54545 (results in pg/mL).

*Despite not having any hypothalamic–pituitary condition at diagnosis or throughout their follow-up, and not having received drugs that suppress the hypothalamic–pituitary–adrenal axis, seven patients with clinical suspicion of primary disease who required replacement therapy presented with normal ACTH levels. Three of them had begun glucocorticoid therapy at the time of SST. In another four cases, there is a strong suspicion that was the case, although the possibility of an inadequate sample processing also existed (ie, sample transport at room temperature).

ACTH, adrenocorticotropic hormone; AI, adrenal insufficiency; SC, serum cortisol; SST, short standard high-dose test.