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Urine pH

Shows how acidic or alkaline your urine is. It moves with diet and some medicines, and it is not the same as your blood pH.

AI-verified against cited sources. Awaiting expert reviewAlso called UA pHLOINC 5803-2

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What it is

Urine pH measures how acidic or alkaline your urine is, on a scale from 0 (very acidic) to 14 (very alkaline). Urine usually falls between about 4.5 and 8. Your kidneys remove extra acid in the urine, so the number moves with what you eat and drink, some medicines and some health conditions. It is a different measurement from the pH of your blood. A test strip gives a rough reading, and a lab pH meter is more precise.

Why it matters

Urine pH is rarely a problem by itself. Clinicians use it for clues about kidney stones, because different stone types form in more acidic or more alkaline urine. They also use it for clues about urinary infections, because some bacteria make urine more alkaline. It helps in reading other strip results too, since very acidic or alkaline urine can throw some of them off. A pattern across several samples says more than one reading.

If it’s low

A lower pH means your urine is more acidic. This is common with a diet high in meat, fish, cheese or other protein. It can also happen with diarrhea, going without food, or when the body has too much acid in its fluids. Acidic urine is linked to some types of kidney stones.

Common causes

  • A diet high in meat, fish, cheese and other protein, or in acidic fruits such as cranberries
  • Diarrhea
  • Fasting or starvation
  • Methenamine, a medicine used to help prevent urinary infections
  • Too much acid in body fluids (metabolic acidosis), for example in diabetic ketoacidosis

What can help

  • Ask your clinician whether the pattern matters for kidney stones, if you have had them
  • Ask your clinician before changing your diet to shift your urine pH

If it’s high

A higher pH means your urine is more alkaline. This is common and often just reflects a diet rich in fruits and vegetables. Less often, it is linked to certain medicines, vomiting, a urinary infection with bacteria that make urease (such as Proteus), or a kidney problem with removing acid. One reading rarely means much on its own.

Common causes

  • A diet high in fruits, vegetables and non-cheese dairy products
  • Citrate or bicarbonate medicines, or a medicine such as acetazolamide
  • Urinary infection with urease-making bacteria such as Proteus
  • Vomiting or stomach suction, where the body loses stomach acid
  • Kidney conditions that limit acid removal, such as renal tubular acidosis
  • Kidney failure

What can help

  • Keep your usual diet in the days before the test so the result reflects your normal
  • Ask your clinician whether a repeat sample or a urine culture makes sense, especially if you have urinary symptoms
  • If you have had kidney stones, ask what your urine pH means for the type of stone you form

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

For adults: 5–7.5 pH. Source: Labcorp, Cleveland Clinic, MedlinePlus Medical Encyclopedia (U.S. National Library of Medicine), American Family Physician 2022;106(1):27-35B, American Family Physician 2005;71(6):1153-1162.

What can affect your result

  • Diet: plant-rich meals raise pH, while meat, fish and cheese lower it
  • Medicines, including citrate, bicarbonate, acetazolamide and thiazide diuretics
  • Vomiting, diarrhea, fasting and other illness
  • How old the sample is when it is tested
  • Test method: strips are read in steps of 0.5 to 1 unit, while a pH meter is more precise
  • Diet: fruits, vegetables and non-cheese dairy raise urine pH, while fish, meat and cheese lower it. Eat your usual balanced diet in the days before the test.
  • Some medicines change urine pH, including acetazolamide, ammonium chloride, methenamine mandelate, potassium citrate, sodium bicarbonate and thiazide diuretics. Do not stop any medicine without talking to your clinician.
  • Urine that sits for hours before testing can give unreliable results. Samples should be tested promptly or refrigerated.
  • Strips are read in steps of about 0.5 to 1 pH unit, so a strip is less precise than a lab pH meter.
  • Urinary infection with urease-making bacteria such as Proteus can raise urine pH.

Urine pH changes with diet, medicines and illness, so one sample is a snapshot and can differ from the next.

When to talk to a clinician

No urine pH value needs urgent action by itself. Talk with your clinician if an unusual pH comes with burning when you urinate, fever, pain in your side or back, or blood in your urine, or if you have had kidney stones.

Questions you could ask

  • Is a dipstick pH enough for my situation, or would a more precise measurement help?
  • Could my diet, a medicine or a supplement explain this result?
  • Should we repeat the test or check for a urinary infection?
  • Could my diet or a recent illness explain this result?
  • If I have had kidney stones, does my urine pH matter for the type I form?

Questions people ask

Is urine pH the same as blood pH?

No. They are two different measurements. Your kidneys adjust the acid in urine to help keep your blood balance steady, so urine pH moves with diet and other things while blood pH stays in a narrow range. A urine pH result does not tell you your blood pH.

What is a normal urine pH?

Urine pH can range from about 4.5 to 8. Labcorp prints 5.0 to 7.5, other sources give 5.0 to 8.0 or 4.6 to 8.0, and values are often between 5.5 and 6.5. Ranges differ between labs, so use the range printed on your report.

Can my diet change my urine pH?

Yes. Fruits, vegetables and non-cheese dairy raise urine pH, and fish, meat and cheese lower it. That is why clinicians ask you to eat your usual balanced diet before the test.

Does a high urine pH mean I have an infection?

Not by itself. Some bacteria, such as Proteus, can make urine more alkaline, but diet, medicines and other conditions raise it too. Clinicians look at the other urinalysis results and your symptoms.

Should I change my diet to change my urine pH?

Only if your clinician suggests it, for example because you form kidney stones. What helps depends on the type of stone, so ask your clinician what target, if any, makes sense for you.

Show the science and sources

For clinicians and researchers

Dipstick pH pads use indicator dyes and are read visually or by reflectance in steps of about 0.5 to 1 unit (for example 5, 6, 6.5, 7, 8 and 9 on one common analyzer). A pH meter reads finer and has its own LOINC code. Urine pH can range from about 4.5 to 8, and a usual value of 5.5 to 6.5 reflects the daily acid load, with protein-rich diets and acidic fruits lowering it and high-citrate diets raising it. Urine pH generally tracks serum pH except in renal tubular acidosis: failure to acidify urine below about 5.5 despite an overnight fast and an acid load is the hallmark of RTA, and in type 1 (distal) RTA the serum is acidic while the urine is alkaline (AFP 2005). Urease-positive organisms such as Proteus split urea to ammonia and raise urine pH. In stone formers, low pH goes with uric acid, cystine and calcium oxalate stones, and high pH with calcium phosphate and infected struvite or staghorn stones (AFP 2022). A random dipstick pH is not the same measurement as the 24-hour urine pH used in stone work-ups (urine-ph-24h). Urine pH also affects other pads: a pH below 5.1 can cause a falsely negative blood pad and a pH below 6.0 a falsely negative nitrite pad (AFP 2005), and a high pH can cause a falsely negative glucose pad (AFP 2022). Alkaline urine can look cloudy from precipitated phosphate crystals.

LOINC 5803-2 (primary), 2756-5, 50560-2, 106930-1. Specimen: urine.

Sources

  1. Urine pH test, MedlinePlus Medical Encyclopedia (U.S. National Library of Medicine) (2025)
  2. Urinalysis: What It Is, Purpose & Results, Cleveland Clinic (2024)
  3. Office-Based Urinalysis: A Comprehensive Review, American Family Physician 2022;106(1):27-35B (2022)
  4. Urinalysis: A Comprehensive Review, American Family Physician 2005;71(6):1153-1162 (2005)
  5. Automated urine sediment analyzers underestimate the severity of hematuria in glomerular diseases, Scientific Reports 2021;11:20981 (2021)
  6. Urinalysis, Complete (test 003772) sample patient report with reference intervals, Labcorp (2026)
  7. Urinalysis, Complete With Microscopic Examination (test 003772), Labcorp
  8. LOINC codes verified with the NLM Clinical Tables LOINC search (e.g. 5803-2), U.S. National Library of Medicine

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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