Urine pH

• 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

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., Inc.