Hemoglobin is a molecule attached to red blood cells that helps move oxygen and carbon dioxide through the body.
Red blood cells have an average life span of 120 days. After this time, they are broken down into parts that can make a new red blood cell. This typically takes place in the spleen, bone marrow, and liver. If the red blood cells break down the blood vessels, their parts move freely in the bloodstream.
If the level of hemoglobin in the blood rises too high, then hemoglobin begins to appear in the urine. This is called hemoglobinuria.
This article focuses on the urine test done to diagnose hemoglobinuria. There are two different types:
Urine - hemoglobin
How the test is performed
A clean-catch (midstream) urine sample is needed.
Men or boys should first 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.
In infants, 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 boys, the entire penis can be placed in the bag and the adhesive attached to the skin. For girls, 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. The urine is drained into a container for transport back to the health care provider.
How to prepare for the test
No special preparation is necessary for this test. If the collection is being taken from an infant, a couple of extra collection bags may be necessary.
How the test will feel
The test involves only normal urination.
Why the test is performed
This test may be used to help diagnose:
Normally, hemoglobin does not appear in the urine.
What abnormal results mean
Hemoglobinuria may be a result of any of the following:
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 28.
Brodsky RA. Paroxysmal nocturnal hemoglobinuria. In: Hoffman R, Benz EJ, Shattil SS, et al, eds. Hematology: Basic Principles and Practice. 5th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2008:chap 30.
Linda J. Vorvick, MD, Medical Director and Director of Didactic Curriculum, MEDEX Northwest Division of Physician Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, David R. Eltz, Stephanie Slon, and Nissi Wang.