Dopamine, Plasma details

Measurement of dopamine levels in urine or blood in addition to urinary vanillylmandelic acid (VMA) and homovanillic acid (HVA) levels may aid in the biochemical diagnosis and monitoring of neuroblastomas [1]. This test may also be useful in evaluating dopamine-secreting pheochromocytomas and paragangliomas (PPGLs) [2].

Neuroblastomas occur predominantly in children and are the most common malignancy under 1 year old. Neuroblastomas are catecholamine-metabolizing tumors, and thus catecholamine metabolites (including VMA and HVA) are more reliable than catecholamines as biochemical markers for neuroblastomas [1]. However, urinary VMA and HVA levels may have limited accuracy for diagnosis of neuroblastomas with high-risk metastatic biology [1]. Because poor prognosis is associated with immaturity of catecholamine metabolism, dopamine levels in urine or blood have been proposed as an additional marker to aid in diagnosis and monitoring of neuroblastomas [3].

Most PPGLs secrete catecholamines, but the relative amount of dopamine, norepinephrine, and epinephrine varies widely. Measurements of plasma free or urinary fractionated metanephrines (ie, the O-methylated catecholamine metabolites) are recommended by the Endocrine Society for the initial biochemical testing of PPGLs [4]. In patients with high clinical suspicion but normal blood pressure and normal levels of metanephrines, measurement of dopamine and its metabolites (HVA and methoxytyramine) may help diagnose PPGLs that predominantly secrete dopamine [2].

The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.

References

1. Eisenhofer G. Monoamine-producing tumors. In: Rifai R, et al. eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elsevier Inc; 2022.

2. Jain A, et al. Pediatr Nephrol. 2020;35(4):581-594.

3. Brodeur GM, et al. J Clin Oncol. 1993;11(8):1466-1477.

4. Lenders JW, et al. J Clin Endocrinol Metab. 2014;99(6):1915-1942