Table 1.
Diagnostic procedures commonly used in evaluation of hypercortisolemia.
| Diagnostic procedure | Clinical use | Cutoff values |
|---|---|---|
| First- and second-line screening tests for hypercortisolemia | ||
| 24-h UFC | Suspicion of hypercortisolemia – screening test | Depends on laboratory and assay method |
| Low-dose overnight DST | Suspicion of hypercortisolemia – screening test | <50 nmol/l (1,8 µg/dl) in healthy subjects |
| Late-night salivary cortisol | Suspicion of hypercortisolemia – screening test | Cut-off values vary depending on population and assay method (20, 22–24) |
| Two-day LDDST | Suspicion of hypercortisolemia – screening test | <50 nmol/l (1,8 µg/dl) in healthy subjects |
| Late-night serum cortisol | Suspicion of hypercortisolemia | <50 nmol/l (1,8 µg/dl) in sleeping healthy subjects |
| Two-day LDDST with consecutive CRH test |
Suspicion of hypercortisolemia, useful in non-neoplastic hypercortisolemia | Serum cortisol stays suppressed <38 nmol/l (1,4 µg/dl) after CRH administration in healthy subjects and non-neoplastic hypercortisolemia |
| DDAVP stimulation test | Suspicion of ACTH-dependent hypercortisolemia, useful in cyclic hypercortisolemia, useful in distinguishing between neoplastic and non-neoplastic hypercortisolemia (25) |
Increase of plasma ACTH by at least 50% in ACTH-dependent cases |
| Hair cortisol | Suspicion of hypercortisolemia, useful in cyclic hypercortisolemia |
Depends on laboratory and assay method |
| Evaluation of origin of hypercortisolemia | ||
| Morning plasma ACTH | Evaluation of origin of hypercortisolemia (ACTH-dependent vs. ACTH-independent) |
>20 pg/ml in ACTH-dependent cases <10 pg/ml in ACTH-independent cases |
| CRH stimulation test | Evaluation of origin of ACTH-dependent hypercortisolemia, useful in distinguishing between ACTH-dependent and ACTH-independent neoplastic hypercortisolemia when ACTH is indeterminate (10-20 pg/ml) (26) |
Increase of plasma ACTH by 35-50% or serum cortisol by 14-20% in ACTH-dependent cases of pituitary origin |
| Two-day HDDST | Evaluation of origin of ACTH-dependent hypercortisolemia, however its use remains controversial | Drop of serum cortisol by at least 50% in corticotropinoma |
DST, dexamethasone suppression test; LDDST, low-dose dexamethasone suppression test; HDDST, high-dose dexamethasone suppression test; ACTH, corticotropin; CRH, corticoliberin; DDAVP, desmopressin; UFC, urinary free cortisol.