We read with great interest the paper by Dr Oklu and coworkers on the use of desmopressin during inferior petrosal sinus sampling (IPSS) as an alternative to corticotropin-releasing hormone (CRH) for the diagnostic investigation of Cushing's disease.1 As the authors report, evidence collected in small series suggests that desmopressin achieves an equivalent diagnostic accuracy to CRH and thus appears to be a tempting and less expensive alternative. It is worth recalling, however, that desmopressin is also a potent hemostatic agent and that patients with Cushing's syndrome are at increased risk for thromboembolic events,2 some even occurring during IPSS performed at expert centers.3 In this context, we have recently observed that endothelial factors are released upon administration of desmopressin to patients with Cushing's disease,4 although the dose used for diagnostic purposes is roughly half the hemostatic dosage. The magnitude of the increase in von Willebrand factor, a promoter of platelet adhesion to the subendothelium in the early phases of hemostasis, was comparable to that observed in healthy subjects and possibly counterbalanced by increased fibrinolytic factors, but the extent to which these changes might affect general hemostatic processes remains to be ascertained. As a consequence, as long as no further evidence is available on the safety of this hemostatic agent during endovascular damages, procedures which are themselves at risk for vascular events, extreme caution should be exercised when using desmopressin instead of CRH during IPSS.