Biochemical Profiles of Patients with Succinate Dehydrogenase B Gene Mutation-Related Adrenal Pheochromocytoma

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: MON 37-82-Pheochromocytoma & Paraganglioma
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-52
Jaydira Del Rivero*1, Victoria L Martucci1, Karen T Adams1 and Karel Pacak2
1Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 2National Institutes of Health (NIH), Bethesda, MD
Background: Pheochromocytomas (PHEOs) are catecholamine-producing tumors of the adrenal medulla and extraadrenal chromaffin cells. One third of these tumors are hereditary, involving mutations in one of the eleven well-known susceptibility genes (RET, VHL, SDHA, SDHB, SDHC, SDHD, SDHAF2, NF1, TMEM127, MAX, HIF2α). Patients with mutations in the tumor suppressor genes encoding the B, C, and D subunits of the succinate dehydrogenase complex (SDHx), present mainly with extra-adrenal PHEO. For patients with SDHB mutations, the majority of these tumors are located in the abdomen. It has been well established that these tumors produce mainly norepinephrine and/or dopamine, while 10% of tumors are biochemically silent. Patients with elevated norepinephrine levels present with typical signs and symptoms such as hypertension, palpitations, and flushing, and patients with elevated dopamine levels usually present in the same manner as biochemically silent tumors (pain due to tumor mass effect). SDHB mutations are much less commonly associated with adrenal PHEO, and biochemical phenotype data is still lacking. This prompted us to assess the biochemical profile of our patients in order to provide additional important information on how to recognize SDHB-related PHEO.  

Methods: The study included seven patients with histologically confirmed adrenal PHEO in the setting of an SDHB mutation. The patients had a mean age of 30 years at diagnosis and were benign at presentation. Plasma and/or 24-hr urinary catecholamine and metanephrine levels were measured. Genetic mutation analysis was performed at Mayo Clinic Laboratories.

Results: SDHB-related adrenal PHEOs showed increased catecholamine production. All our patients showed an increase in plasma and urine norepinephrine and normetanephrine. None of the patients showed an elevation of the plasma or urinary metanephrine, epinephrine, or dopamine.

Conclusions: Here we present that SDHB-related adrenal PHEOs typically have a noradrenergic biochemical profile, as evidenced by the elevation of urine and plasma norepinephrine and normetanephrine.

Nothing to Disclose: JD, VLM, KTA, KP

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