Normal pH Range of Urine

The normal pH of urine is approximately 5.0 to 6.0, with an average of around 5.5 to 6.0. 1

Understanding Urinary pH

Urine pH is an important physiological parameter that reflects the body's acid-base balance and kidney function 1
In the distal tubules and collecting system of the kidney, the pH of urine is approximately 5, which affects the solubility of various substances 1
Normal urine pH can range from 4.5 to 8.0, but typically averages between 5.0 and 6.0 in healthy individuals 1
Urine pH can fluctuate throughout the day based on diet, hydration status, and metabolic activity 2

Acidic urine (pH ≤5.5) can increase the risk of uric acid stone formation, as uric acid has a pKa of 5.4 to 5.7 and is poorly soluble in water 1
At a urinary pH of approximately 5, the solubility of uric acid is only about 15 mg/dL, increasing the likelihood of crystal formation and deposition 1
Persistently acidic urine (pH <5.0) is associated with increased prevalence of kidney disease, including nephrolithiasis, renal cysts, microhematuria, and proteinuria 3
Samples with pH >8 are unsuitable for analysis of urine oxalate, as oxalogenesis can occur in vitro under such conditions 1

Diet: High protein diets tend to produce more acidic urine, while vegetarian diets tend to produce more alkaline urine 1
Medical conditions: Type 2 diabetes is associated with excessively low urine pH (average 5.45), increasing the risk for uric acid nephrolithiasis 4
Medications: Some medications can alter urinary pH, such as methenamine salts which require maintaining urinary pH below 6.0 for effectiveness 1
Chronic heart failure: Acidic urine (pH ≤5.5) is associated with poor prognosis in patients with chronic heart failure 5

A single pH measurement from a spot urine sample is not reliable to identify individuals with consistently acidic or alkaline pH 2
For accurate assessment of a patient's typical urinary pH, multiple measurements should be taken (morning and evening) over several consecutive days 2
Urine pH can be measured using pH strips or a pH meter, with pH strips showing good correlation (0.94-0.95) with pH meter measurements 2
For 24-hour urine collections, samples should be collected into acid or acidified within 24 hours after collection to achieve a pH of <2 to aid sample preservation and solubility of certain compounds 1

Maintaining urinary pH between 6.2 and 6.9 is associated with the highest eGFR and lowest prevalence of nephrolithiasis, microhematuria, and proteinuria in patients with gout 3
For uric acid stone formers, urine pH should be increased to 6.0 using potassium citrate therapy 1
For cystine stone formers, a urine pH of 7.0 should be achieved to increase cystine solubility 1
Alkalization of urine has been shown to improve symptoms in patients with overactive bladder who have acidic urine 6