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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

This test measures how acidic your urine is. 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.

Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

What abnormal results mean

A high urine pH may be due to:

  • Gastric suction
  • Kidney failure
  • Kidney tubular acidosis
  • Urinary tract infection
  • Vomiting

A low urine pH may be due to:

  • Diabetic ketoacidosis
  • Diarrhea
  • Starvation

The test also may be performed to investigate:

  • Alkalosis
  • Interstitial nephritis
  • Acidosis
  • Sepsis

What the risks are

There are no risks.

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

Bazari H. Approach to the patient with renal disease. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 115.

Review Date: 8/7/2009

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Information developed by A.D.A.M., Inc. regarding tests and test results may not directly correspond with information provided by UCSF Medical Center. Please discuss with your doctor any questions or concerns you may have.