Endogenous restoration of noradrenaline by precursor therapy in dopamine-beta-hydroxylase deficiency.

DL-dihydroxyphenylserine was given by mouth in a single-blind, placebo-controlled trial to two patients with orthostatic hypotension due to dopamine-beta-hydroxylase deficiency, in the hope of providing noradrenaline by endogenous decarboxylation. Dose-dependent increases in blood pressure were obtained over the range 150-600 mg. After 600 mg mean arterial pressure rose 33 and 19 mm Hg and these rises were tightly correlated with an increase in plasma noradrenaline (r = 0.995, p less than 0.001 and r = 0.88, p less than 0.05). Urinary noradrenaline increased from undetectable levels to 338 and 511 micrograms/24 h. Standing time (a correlate of functional capacity) also increased significantly in both patients. No side-effects were noted.