Desmopressin test during petrosal sinus sampling: a valuable tool to discriminate pituitary or ectopic ACTH-dependent Cushing's syndrome.
Corticotropin-releasing hormone (CRH)-stimulated petrosal sinus sampling is currently the gold standard method for the differential diagnosis between pituitary and ectopic ACTH-dependent Cushing's syndrome. Our objective was to determine sensitivity and specificity of desmopressin test during petrosal sinus sampling.


METHODS
Forty-three patients had petrosal sinus sampling because of the lack of visible adenoma on magnetic resonance imaging (MRI) and/or because of discordant cortisol response to high-dose dexamethasone suppression test. ACTH sampling was performed in an antecubital vein, right and left petrosal sinuses, then at each location 5 and 10 min after injection of desmopressin. Diagnosis was based on the ACTH ratio between petrosal sinus and humeral vein ACTH after desmopressin test. Diagnosis was confirmed after surgery. A receiver operating characteristics curve was used to determine optimal sensitivity and specificity.


RESULTS
Thirty-six patients had Cushing's disease (CD) and seven had ectopic ACTH secretion. A ratio > 2 after desmopressin was found in 35 of the 36 cases of CD (sensitivity: 95%). A ratio < or = 2 was found in the seven patients with ectopic ACTH secretion (specificity: 100%). Sinus sampling was ineffective in determining the left or right localization of the adenoma (sensitivity = 50%). No major adverse effects were observed during or after the procedure.


CONCLUSIONS
Desmopressin test during petrosal sinus sampling is a safe and effective diagnostic procedure in ACTH-dependent Cushing's syndrome. It thus represents a valuable alternative to CRH.
Castinetti
F
F
Federation of Endocrinology, Diabetes, Metabolic Diseases and Nutrition, Hôpital de la Timone, Centre Hospitalier Universitaire de Marseille, Marseille, France.
Morange
I
I
Dufour
H
H
Jaquet
P
P
Conte-Devolx
B
B
Girard
N
N
Brue
T
T
D000182:ACTH Syndrome, Ectopic / Q000175:diagnosis*; D049913:ACTH-Secreting Pituitary Adenoma / Q000150:complications / Q000175:diagnosis*; D000293:Adolescent; D000328:Adult; D050034:Antidiuretic Agents; D002648:Child; D003480:Cushing Syndrome / Q000175:diagnosis* / Q000209:etiology; D003894:Deamino Arginine Vasopressin; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017591:Petrosal Sinus Sampling / Q000379:methods* / Q000592:standards; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
D050034:Antidiuretic Agents; D003894:Deamino Arginine Vasopressin