The effects of the noradrenaline precursor, L-threo-3,4-dihydroxyphenylserine, in children with orthostatic intolerance.

To evaluate the usefulness of L-threo-3,4-dihydroxyphenylserine (L-DOPS), a precursor of noradrenaline, in the treatment of orthostatic intolerance in children, we examined the circulatory responses to orthostatic stress and clinical symptoms before and after medication. Seven children with orthostatic intolerance, two boys and five girls, aged 11-15 years (mean age 13.3 years), were studied. L-DOPS (100-200 mg) was administered orally once or twice a day for 4 weeks. Blood pressure (BP) and heart rate (HR) were measured with a non-invasive beat-to-beat method (Finapres). All had a marked reduction in BP (delta SBP/DBP = -50 +/- 9/-27 +/- 6 mmHg) with prolonged recovery time in the initial phase during standing. After L-DOPS for 4 weeks, BP reduction in the initial phase was significantly attenuated (delta SBP/DBP = -37 +/- 9/-17 +/- 7 mmHg, p < 0.05) and recovery time was normalized in all, although supine BP and HR were unchanged. Two reported relief of all symptoms, while in five symptoms were markedly improved. There were no adverse effects reported. These preliminary studies have indicated that L-DOPS may be an effective drug for the treatment of orthostatic intolerance in children.