At a glance:
Reasonable measurement methods
Possibilities and limits of measuring pH
Urinary pH measurement does not provide a reliable assessment of acid-base balance! Due to nutritional influences, the urinary pH ranges between 5 and 8. Apart from that only 1% of total urinary acid is excreted as free acid detectable by paper strips. Most of the urinary acid is excreted as ammonium compounds which is undetectable by the pH colour indicator.
Measuring pH values is only helpful if the pH value in the urine is measured regularly several times per day at relatively short intervals. In addition, you should have always eaten the same food and be free of kidney problems. If these requirements are met, measuring pH with pH test strips over the course of the day can provide an indication of the status of acid-base balance.
Determine net acid excretion instead of pH
Acid-base balance can be accurately determined by measuring net acid excretion within one day. The urine collected over 24 hours is analysed for all excretion products relevant to assessing acid-base status, which means that net acid excretion for a day can be determined.
Friedrich Sander method (urine pH)
Developed by Sander in the 1930s this method is still used today. In addition to urine pH, the urine’s buffer capacity is determined through five measurements spread out over the day. Interpretation by a specialist is necessary for this method.
The method developed by Jörgensen and Stirum
This method determines the buffer capacity of the blood - in particular the of red blood cells’ one and hence about the possible degree of acidosis within the cells. This specific blood analysis is used by special laboratories.