Inferior Petrosal Sinus Sampling

Indications

• Detect or confirm the laterlization of ACTH-producing adenoma in patients with ACTH-dependent Cushing’s disease.

Procedure

Inferior petrosal sinuses are catheterized bilaterally. Simultaneous samples for ACTH are obtained from each petrosal sinus and peripherally. Samples are drawn at baseline then 3, 5, and 10 minutes after intravenous CRH or ddAVP administration.

Interpretation

• ACTH in petrosal sinus : peripheral > 2 before CRH/ddAVP administration or > 3 after ACTH administration indicates pituitary source of ACTH (as opposed to ectopic ACTH production).
• ACTH on one side : other > 1.4 lateralizes the tumour to that side.
• In 396 patients with a lateral adenoma, lateralization using IPSS was correct in 69% and incorrect in 31%. [Wind 2013]

References

• Joshua J. Wind, Russell R. Lonser, Lynnette K. Nieman, Hetty L. DeVroom, Richard Chang, Edward H. Oldfield. The Lateralization Accuracy of Inferior Petrosal Sinus Sampling in 501 Patients With Cushing’s Disease. JCEM, Volume 98, Issue 6, 1 June 2013, Pages 2285–2293.