A case of hyperdopaminuria due to increased renal dopamine production

Increasing evidence suggests that dopamine is synthesized within the kidney and that this intrarenally formed dopamine plays a role in sodium handling. We report on a case, in which a patient had markedly elevated urinary dopamine levels, due to increased renal dopamine synthesis, while receiving chronic corticosteroid therapy. Blockade of the renal dopamine synthesis, by carbidopa, markedly reduced urinary dopamine output and urinary sodium excretion. These findings provide further evidence for the hypothesis that intrarenal dopamine plays a role in sodium handling and may be of pathophysiological importance in counteracting the sodium-retaining effects of chronic corticosteroid therapy.