URINARY-EXCRETION OF 5-S-CYSTEINYLDOPA AND 6-HYDROXY-5-METHOXYINDOLE-2-CARBOXYLIC ACID IN CHILDREN

5-S-Cysteinyldopa (5SCD) and 6-hydroxy-5-methoxyindole-2-carboxylic ac id (6H5MI2C) are formed during biosynthesis of melanins. They are used as indicators of pigment formation and markers of melanoma progressio n in adults and could possibly be used as markers of activity, growth and even malignant transformation in large pigmented naevi in children . We investigated the urinary excretion of these pigment precursor met abolites from 136 children, 5 to 15 Sears of age. The mean 5SCD excret ion mas 38.1 mu mol/mol creatinine. A significant age-related decrease from a mean of 60.4 mu mol/mol creatinine at 5 years of age to 28.0 m u mol/mol creatinine at age 15 was found. In a reference group (29 adu lts, 20-33 years of age) the mean excretion mas 48.9 mu mol/mol creati nine. The mean excretion of 6H5MI2C was 42.8 mu mol/mol creatinine at 5 Sears of age and 26.1 mu mol/mol creatinine at the age of 15. The me an value for the young adults was 33.4 mu mol/mol creatinine. No corre lation between the mean excretion of 5SCD and 6H5MI2C was demonstrated . We suggest an upper reference level of 90 mu mol/mol creatinine for the excretion of 5SCD in the age group 5-11 years and of 60 mu mol/mol creatinine in the age group 13-15 years. Corresponding figures for th e indole 6H5MI2C are 70 and 60 mu mol/mol creatinine. The establishmen t of reference values in children mill make it possible to use SSCD an d 6H5MI2C measurements as diagnostic tools, indicating growth or malig nant transformation in giant melanocytic naevi during childhood.