Phaeochromocytoma in a patient with Parkinson's disease : diagnostic dilemma

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

Poster Board MON-51
Harpreet Kaur*1 and Roberto Emilio Izquierdo2
1SUNY Upstate Med Univ, Syracuse, NY, 2SUNY Upstate Medical University, Syracuse, NY
Case report: A 79 year old female with a known history of Parkinson’s disease for 5 years on Levodopa/Carbidopa (L-dopa) and pramipexole, and breast cancer on anastrozole presented with abdominal pain and severe constipation, CT abdomen /pelvis done showed heterogeneous mass that measured 10.5 x 9.4x 9.9 cm in left adrenal gland. Prior to this, she had also been complaining of headaches, palpitations, dizziness, pre syncopal episodes and hot flashes for 2 years, worsening gradually with time. These symptoms were presumed by her physicians to be secondary to the dopaminergic drugs, which can cause orthostatic hypotension and to anastrazole, which causes hot flashes as a side effect.

A 24 hour urine collection was done which revealed elevated levels of catecholamines. The elevated levels of dopamine 5022 mcg/day (normal range: 60-440 mcg/day) were felt to be due to her L-dopa treatment but she also had concurrent elevations of norepinephrine 1726 mcg/day (0-100 mcg/day), epinephrine 225 mcg/day (0-25 mcg/day), metanephrine 93440 nmol/day (152-1775 nmol/d) and normetanephrine 189216 nmol/d (273-3548 nmol/d).

Pre operative management could not include phenoxybenzamine as patient had significant orthostatic hypotension. Alternatively, nicardepine was used. Her intra and post operative course was uneventful. Following surgery, despite ongoing L-dopa treatment, her 24 urine demonstrated normal catecholamines excretion except elevated dopamine level. Her symptoms resolved.

Discussion: The coexistence of Parkinson’s disease being treated with dopaminergic medications in a patient, being evaluated for phaeochromocytoma confounds the interpretation of biochemical tests. This unusual case provided the opportunity to analyze the combined effects of L-dopa therapy and phaeochromocytoma secretion on urinary-excreted catecholamines and their metabolites. Literature review has shown significant increase in urinary dopamine levels in patients treated with L-dopa, with severity of elevation related to drug dose. It has been demonstrated that therapeutic doses of L-dopa does not result in abnormally elevated excretion of vanillyl mandelic acid,5-hyroxyindoleacetic acid, noradrenaline or adrenaline or exhibits a correlation with the daily dose of L-dopa.

 Conclusion: Physicians should be aware of the effect of L-dopa on urinary catecholamines as a confounder in the evaluation of pheochromocytoma.

(1)  D F Davidson , K Grosset and D Grosset. Parkinson's disease: the effect of L-dopa therapy on urinary free catecholamines and metabolites. Ann Clin Biochem.2007;44:364-68. (2) Mehta SH et al. Diagnosis of pheochromocytoma in the setting of Parkinson disease. Nat Rev Neurol. 2009;5(6):343-7.

Nothing to Disclose: HK, REI

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