Acid loading test (pH)

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Female urinary tract

Male urinary tract

The acid loading test (pH) measures the ability of the kidney tubules to acidify urine when there is increased plasma acidity.

See also: Urine pH

You'll be told to take ammonium chloride capsules by mouth for 3 days. Then, a urine and blood sample are taken. (The blood sample is needed to show that the ammonium chloride made the blood slightly acidic.) The laboratory measures the level of acid found in both samples.

For information on how the urine and blood samples are obtained, see:

• Clean catch urine collection
• Venipuncture (blood draw)

Your doctor will tell you to take ammonium chloride capsules by mouth for 3 days prior to the test.

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

This test is done to see how well your kidneys control the body's acid-base status.

Review Date: 12/02/2009
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Herbert Y. Lin, MD, PHD, Nephrologist, Massachusetts General Hospital; Associate Professor of Medicine, Harvard Medical School. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).

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