Melanin - urine

Alternative names
Thormahlen’s test; Urine melanin

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

How the test is performed

Collect a “clean-catch” (midstream) urine sample. To do so, men and 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.

As you start to urinate, allow a small amount to fall into the toilet bowl (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. Give the container to the health care provider or assistant.

For an infant:
Thoroughly wash the area around the urethra. Open a Urine collection bag (a plastic bag with an adhesive paper on one end), and place it on your infant. For males, the entire penis can be placed in the bag and the adhesive attached to the skin. For females, the bag is placed over the labia. Place a diaper over the infant (bag and all).

Check your baby frequently and remove the bag after the infant has urinated into it. For active infants, this procedure may take a couple of attempts - lively infants can displace the bag, causing an inability to obtain the specimen. The urine is drained into a container for transport back to the health care provider.

How to prepare for the test
If you are collecting urine from an infant, it may be helpful to have a few spare collection bags.

How the test will feel
The test involves only normal urination.

Why the test is performed

Malignant melanoma is a cancerous tumor of the skin cells that produce pigment. This disease is usually visible on the skin, but if the malignant cells metastasize to internal areas of the body, you may never see the cancer.

If the skin cell tumors are growing within the body (especially within the liver), melanin may be produced in sufficient quantities to be present in the urine.

This test measures the absence or presence of melanin in the urine.

Normal Values
Normally, melanin is not present in urine.

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.

Johns Hopkins patient information

Last revised: December 4, 2012
by Harutyun Medina, M.D.

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