Urine melanin

Definition

Urine melanin 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 Values

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 doctor about the meaning of your specific test results.

What abnormal results mean

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

What the risks are

There are no risks associated with this test.

Special considerations

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

Figures

References

McPherson RA, Ben-Ezra J, Zhao S. Basic examination of urine. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 27.

Revision

Last reviewed 9/9/2012 by David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.

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