Urine melanin
Thormahlen's test; Melanin - urine
Urine melanin test is a test to determine the abnormal presence of melanin in the urine.
A clean-catch urine sample is performed by collecting the sample of urine in midstream. Men or boys should wipe clean the head of the penis. Women or girls need to wash the area between the lips of the vagina with soapy water and rinse well. A small amount of urine should initially fall into the toilet bowl before it is collected (this clears the urethra of contaminants). Then, in a clean container, catch about 1 to 2 ounces of urine and remove the container from the urine stream. The container is then given to the health care provider.
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
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.
Version Info
Last reviewed on: 10/16/2022
Reviewed by: Mark Levin, MD, Hematologist and Oncologist, Monsey, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
