Urinary excretion of 5-S-cysteinyldopa in healthy Japanese.

Urinary excretion of 5-S-cysteinyldopa was investigated in 20 healthy Japanese (10 men and 10 women). The values of excretion varied between 46 and 193 microgram/24 h. The mean (+/- S.D.) was 96 1 +/- 9.8 microgram/24 h. It was higher in the men than in the women, being 13 +/- 15 vis-a-vis 80.8 +/- 11.4 microgram/24 h. This finding indicates that 5-S-cysteinyldopa is formed and excreted by active melanocytes even in Mongoloids. The excretion of dopa and dopamine was found not correlative with the excretion of 5-S-cysteinyldopa.