Inferior petrosal sinus sampling explained

Inferior petrosal sinus sampling (or IPSS), is a diagnostic medical procedure used to determine whether excess adrenocorticotropic hormone (ACTH) is coming from the pituitary gland (usually a pituitary adenoma causing Cushing's disease) or from a source outside the pituitary (a rare tumor causing ectopic ACTH syndrome). The procedure is usually reserved for patients with consistent ACTH-dependent Cushing's syndrome without a clear cut lesion on pituitary MRI.^[1]

Procedure

The procedure is typically performed in large medical centers by an experienced interventional radiologist, neurologist or neurosurgeon and guided using fluoroscopy. Catheters are inserted through the jugular or femoral veins into both inferior petrosal veins which drain blood from the pituitary gland. To maximize and stabilize the pulsatile ACTH secretion, a dose of intravenous corticotropin-releasing hormone (CRH) is usually given. ACTH levels are measured in the petrosal (central) and peripheral venous plasma before and within 10-12 minutes after administration of CRH. Where CRH is unavailable some centers use desmopressin.^[2] Measurement of the central-to-peripheral prolactin ratio can assist in verifying the correct placement of the catheters as well as in normalization of ACTH levels. In experienced centers, successful bilateral catheterization is reported in up to 90% of cases with very rare major complications.^{[3] [4]}

Interpretation

In patients with true hypercortisolism, a central-to-peripheral ACTH gradient of ≥2 before, or ≥3 after CRH administration, is considered diagnostic for a pituitary source of ACTH.^[5] Some studies have shown that if catheters were appropriately placed, a gradient of ≥1.4 for ACTH concentrations between the two sinuses predicted the side of the tumor with ~70% accuracy.^[6]

Further reading

• Fleseriu M, Auchus R, Bancos I, Ben-Shlomo A, Bertherat J, Biermasz NR, Boguszewski CL, Bronstein MD, Buchfelder M, Carmichael JD, Casanueva FF, Castinetti F, Chanson P, Findling J, Gadelha M, Geer EB, Giustina A, Grossman A, Gurnell M, Ho K, Ioachimescu AG, Kaiser UB, Karavitaki N, Katznelson L, Kelly DF, Lacroix A, McCormack A, Melmed S, Molitch M, Mortini P, Newell-Price J, Nieman L, Pereira AM, Petersenn S, Pivonello R, Raff H, Reincke M, Salvatori R, Scaroni C, Shimon I, Stratakis CA, Swearingen B, Tabarin A, Takahashi Y, Theodoropoulou M, Tsagarakis S, Valassi E, Varlamov EV, Vila G, Wass J, Webb SM, Zatelli MC, Biller BM . 6 . Consensus on diagnosis and management of Cushing's disease: a guideline update . The Lancet. Diabetes & Endocrinology . 9 . 12 . 847–875 . December 2021 . 34687601 . 10.1016/S2213-8587(21)00235-7 . 8743006 .

Notes and References

1. Fleseriu M, Auchus R, Bancos I, Ben-Shlomo A, Bertherat J, Biermasz NR, Boguszewski CL, Bronstein MD, Buchfelder M, Carmichael JD, Casanueva FF, Castinetti F, Chanson P, Findling J, Gadelha M, Geer EB, Giustina A, Grossman A, Gurnell M, Ho K, Ioachimescu AG, Kaiser UB, Karavitaki N, Katznelson L, Kelly DF, Lacroix A, McCormack A, Melmed S, Molitch M, Mortini P, Newell-Price J, Nieman L, Pereira AM, Petersenn S, Pivonello R, Raff H, Reincke M, Salvatori R, Scaroni C, Shimon I, Stratakis CA, Swearingen B, Tabarin A, Takahashi Y, Theodoropoulou M, Tsagarakis S, Valassi E, Varlamov EV, Vila G, Wass J, Webb SM, Zatelli MC, Biller BM . 6 . Consensus on diagnosis and management of Cushing's disease: a guideline update . English . The Lancet. Diabetes & Endocrinology . 9 . 12 . 847–875 . December 2021 . 34687601 . 8743006 . 10.1016/S2213-8587(21)00235-7 .
2. Castinetti F, Morange I, Dufour H, Jaquet P, Conte-Devolx B, Girard N, Brue T . Desmopressin test during petrosal sinus sampling: a valuable tool to discriminate pituitary or ectopic ACTH-dependent Cushing's syndrome . European Journal of Endocrinology . 157 . 3 . 271–277 . September 2007 . 17766708 . 10.1530/EJE-07-0215 . 40585442 . free .
3. Kaltsas GA, Giannulis MG, Newell-Price JD, Dacie JE, Thakkar C, Afshar F, Monson JP, Grossman AB, Besser GM, Trainer PJ . 6 . A critical analysis of the value of simultaneous inferior petrosal sinus sampling in Cushing's disease and the occult ectopic adrenocorticotropin syndrome . The Journal of Clinical Endocrinology and Metabolism . 84 . 2 . 487–492 . February 1999 . 10022405 . 10.1210/jcem.84.2.5437 . free .
4. Fischer M, Cahn A, Glaser B, Leibowitz G, Stokar J, Dresner-Pollak R, Cohen JE, Moshe GJ . August 2020 . Inferior petrosal sinus sampling – 16 years of experience from a single tertiary center in Israel . Endocrine Abstracts . en . Bioscientifica . 70 . 10.1530/endoabs.70.AEP698. 225285385 .
5. Oldfield EH, Doppman JL, Nieman LK, Chrousos GP, Miller DL, Katz DA, Cutler GB, Loriaux DL . 6 . Petrosal sinus sampling with and without corticotropin-releasing hormone for the differential diagnosis of Cushing's syndrome . The New England Journal of Medicine . 325 . 13 . 897–905 . September 1991 . 1652686 . 10.1056/NEJM199109263251301 . free .
6. Wind JJ, Lonser RR, Nieman LK, DeVroom HL, Chang R, Oldfield EH . The lateralization accuracy of inferior petrosal sinus sampling in 501 patients with Cushing's disease . The Journal of Clinical Endocrinology and Metabolism . 98 . 6 . 2285–2293 . June 2013 . 23553862 . 3667263 . 10.1210/jc.2012-3943 .