Definition

Urine melanin test is a test to determine the abnormal presence of melanin in the urine.

Alternative Names

Thormahlen's test; Melanin - urine

How the Test is Performed

A clean-catch urine sample is needed.

How to Prepare for the Test

No special preparation is needed.

How the Test will Feel

The test involves only normal urination.

Why the Test is Performed

This test is used to diagnose melanoma, a type of skin cancer that produces melanin. If the cancer spreads (especially within the liver), the cancer may produce enough of this substance that it shows up in the urine.

Normal Results

Normally, melanin is not present in urine.

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your health care provider about the meaning of your specific test results.

What Abnormal Results Mean

If melanin is present in the urine, malignant melanoma is suspected.

Risks

There are no risks associated with this test.

Considerations

This test is rarely done anymore to diagnose melanoma because there are better tests available.

References

Cruz DJS, Gru AA. Tumors of the skin. In: Fletcher CDM, ed. Diagnostic Histopathology of Tumors. 5th ed. Philadelphia, PA: Elsevier; 2021:chap 23.

Mitchell TC, Karakousis G, Schuchter L. Melanoma. In: Niederhuber JE, Armitage JO, Kastan MB, Doroshow JH, Tepper JE, eds. Abeloff's Clinical Oncology. 6th ed. Philadelphia, PA: Elsevier; 2020:chap 66.