Urine melanin is a test to determine the abnormal presence of melanin in the urine.
Thormahlen's test; Melanin - urine
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.
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.
There are no risks associated with this test.
This test is rarely done to diagnose melanoma because there are better tests available.
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: Elsevier Saunders; 2011:chap 27.