Diagnostic Tests in Cushing Syndrome
Diagnosis | Serum Cortisol, 9 AM | Salivary or Serum Cortisol, Midnight | Urinary Free Cortisol | Low-Dose or Overnight Dexamethasone Suppression Test | High-Dose Dexamethasone Suppression Test | Desmopressin Stimulation Test | ACTH Level |
|---|---|---|---|---|---|---|---|
Normal | N | N | N* | S | S | Flat | N |
Cushing disease | N or ↑ | ↑ | ↑ | NS | S | ↑ | N or ↑ |
Ectopic ACTH | N or ↑ | ↑ | ↑ | NS | NS | Flat or ↑ (rarely) | ↑ or ↑↑ |
Adrenal tumor | N or ↑ | ↑ | ↑ | NS | NS | Flat | ↓ |
* May be elevated in non-Cushing conditions. | |||||||
ACTH = adrenocorticotropic hormone; Flat = no significant rise in ACTH or cortisol; N = normal; NS = nonsuppression; S = suppression; ↑↑= greatly increased; ↑= increased; ↓= decreased. | |||||||
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