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Urine pH

Definition

A urine pH test measures the acidity of urine.

See also: Acid loading test

Alternative Names

pH - urine

How the test is performed

A urine sample is needed. For information on collecting a urine sample, see: Clean-catch urine sample

How to prepare for the test

Your health care provider may tell you to stop taking certain drugs that can affect the results of the test.

  • Drugs that increase urine pH include acetazolamide, potassium citrate, and sodium bicarbonate.
  • Drugs that can decrease urine pH include ammonium chloride, thiazide diuretics, and methenamine mandelate.

Eat a normal, balanced diet for several days before the test.

  • A diet high in citrus fruits, vegetables, or dairy products can increase your urine pH.
  • A diet high in meat products or cranberries can decrease your urine pH.

How the test will feel

The test involves only normal urination, and there is no discomfort.

Why the test is performed

Your doctor may order this test to check for changes in your body's acid levels.

It may be done to see if you are at risk for kidney stones. Acidic urine is associated with xanthine, cystine, uric acid, and calcium oxalate stones. Alkaline urine is associated with calcium carbonate, calcium phosphate, and magnesium phosphate stones.

Your doctor may also order this test if you need to take certain medications. Some medications are more effective in acidic or alkaline environments. For example, streptomycin, neomycin, and kanamycin are more effective in treating urinary tract infections when the urine is alkaline.

Normal Values

The normal values range from 4.6 to 8.0.

The examples above are common measurements for results of these tests. 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

A high urine pH may be due to:

A low urine pH may be due to:

The test also may be done under the following conditions:

Special considerations

Urine pH can be affected by various factors after collection such as leaving the urine standing in an uncovered container. Bacteria usually increase the pH as they break down urea in the urine to ammonia.

References

Israni AK, Kasiske BL. Laboratory assessment of kidney disease: glomerular filtration rate, urinalysis, and proteinuria. In: Taal MW, Chertow GM, et al, eds. Brenner & Rector's The Kidney. 9th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 25.


Review Date: 9/3/2012
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.
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