Measurement of eumelanin precursor metabolites in the urine as a new marker for melanoma metastases.

BACKGROUND AND DESIGN

This article introduces a rapid high-performance liquid chromatographic assay to measure urinary pheomelanin and eumelanin metabolites, 5-S-cysteinyldopa and indoles, 5(6)-hydroxy-6(5)-methoxyindole-2-carboxylic acid.

RESULTS

Our high-performance liquid chromatographic study clearly showed (1) urine of melanoma patients with positive metastasis revealed significant amounts of 5-S-cysteinyldopa and indoles (5,6-dihydroxyindole-2-carboxylic acid plus 6-hydroxy-5-methoxyindole-2-carboxylic acid) above 1 mumol/d and 2 mumol/d, respectively; and (2) in patients with metastasis-free melanoma these melanin metabolites might be excreted into the urine but always less than the two values cited above.

CONCLUSIONS

As there is a discrepancy regarding the specificity of 5-S-cysteinyldopa as a marker for estimation of melanoma metastasis, high-performance liquid chromatographic measurement of urinary indoles will provide an additional assay in the detection of melanoma metastasis from an early stage. Both melanoma markers were increased in the urine of patients with metastatic melanoma.