Urine pH

Function

Urine pH measures the acidity or alkalinity of a urine sample. The kidneys play a major role in maintaining the body's acid-base balance by excreting hydrogen ions and reabsorbing bicarbonate. The pH level of urine reflects this ongoing metabolic activity and can vary significantly based on diet and systemic health.

Why it is Ordered

Physicians monitor urine pH to:

• Assist in the diagnosis of metabolic or respiratory acidosis/alkalosis.
• Evaluate the risk of developing specific types of kidney stones (urolithiasis).
• Monitor the effectiveness of medications intended to alkalinize the urine (e.g., for gout treatment).
• Check for Urinary Tract Infections (UTIs), as certain bacteria alter the pH.

Associated Conditions

• Acidic Urine (Low pH): Associated with high-protein diets, starvation, diabetic ketoacidosis, and uric acid stones.
• Alkaline Urine (High pH): Associated with vegetarian diets, Urinary Tract Infections caused by urea-splitting bacteria (like Proteus), and Renal Tubular Acidosis (RTA).
• Kidney Stones: Uric acid and cystine stones form in acidic environments; calcium phosphate and struvite stones form in alkaline environments.

Diet is the most common factor affecting urine pH; for example, citrus fruits, while acidic themselves, actually produce an alkaline urine after metabolism.