Inferior Petrosal Sampling for the Differential Diagnosis of ACTH-Dependent Cushing’s Syndrome

The role of bilateral inferior petrosal sinus sampling in the diagnostic evaluation of cushing’s disease

“…Baseline IPS/P≥2 or CRHstimulated IPS/P≥3 confirms Cushing syndrome (22). False-negative rates for BIPSS range from 1% to 10%.…”

“…We then administer 3 000-5 000 units of heparin. In addition to refraining from cannulating the IPS too centrally, heparin administration is important to avoid IPS and cavernous sinus thrombosis (22).…”

“…False-negative rates for BIPSS range from 1% to 10%. Such cases can be further evaluated by normalizing the ratio to prolactin levels, which must be measured at the time of BIPSS in a similar manner to what has been described elsewhere (22).…”

“…There is general consensus that BIPSS is indicated only once ACTH-dependent hypercortisolemia has been firmly established (13,22). In other words, BIPSS is not meant to diagnose Cushing syndrome, but to diagnose a pituitary source of ACTH hypersecretion.…”

“…If these noninvasive tests fail to distinguish Cushing syndrome from ectopic ACTH secretion or if they provide equivocal or ambiguous results, BIPSS with CRH stimulation is indicated for further evaluation (22).…”