ESA-SRB-AOTA 2019

Investigation of an adrenal incidentaloma leads to an unsuspected diagnosis (#582)

Thomas Chesterman 1 2 , Lachlan Angus 1 , Jui Ho 1 2 , Morton Burt 1 2
  1. Flinders Medical Centre, Bedford Park, SA, Australia
  2. College of Medicine and Public Health, Flinders University, Bedford Park, South Australia, Australia

Introduction:

Phaeochromocytomas and paragangliomas are rare catecholamine producing tumours arising from the adrenal medulla or extra adrenal autonomic paraganglia. Biochemically, they are characterised by elevated plasma or urinary normetanephrine levels. Patients with end stage renal failure typically have higher plasma levels which may make diagnosis more challenging in this setting.

Case:

A 76 year old woman with end stage renal failure was referred for further evaluation of a 25 mm adrenal mass with indeterminate washout characteristics. Initial plasma metanephrines, normetanephrines and 3-methoxytyramine levels were elevated approximately two, nine and four times the upper limit of normal respectively. On repeat testing plasma normetanephrines remained elevated >4 times the upper limit of normal. Surprisingly, Gallium DOTATATE PET scan revealed that the adrenal lesion was not avid, however intense tracer uptake was seen in a nodule in the left carotid sheath. The patient was medically managed with prazosin but declined further surgical or genetic investigation.

Discussion:

Studies consistently demonstrate elevation of plasma normetanephrine and metanephrine levels in patients with renal disease. The kidneys are only responsible for about 15% of the clearance of free metanephrines, therefore the elevated levels are hypothesised to be related to increased sympathetic activation and analytic interference, rather than reduced renal clearance. Adjusted limits of twice the upper limit of normal for metanephrines and at least three times the upper limit of normal for metanephrines have been proposed to account for this increase.

Conclusion:

It is important for clinicians involved in the diagnosis of phaeochromocytomas and paragangliomas to be aware of how renal failure may affect their biochemical investigations.

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  2. Vantomme, B., et al., Diagnosis of pheochromocytoma in a hemodialysis patient through measurement of plasma catecholamines. Hemodial Int, 2016. 20(3): p. E6-9.
  3. Pamporaki, C., et al., Optimized Reference Intervals for Plasma Free Metanephrines in Patients With CKD. Am J Kidney Dis, 2018. 72(6): p. 907-909.
  4. Eisenhofer, G. and M. Peitzsch, Laboratory evaluation of pheochromocytoma and paraganglioma. Clin Chem, 2014. 60(12): p. 1486-99