At a glance:
Resonable measurement methods
Possibilities and limits of measuring pH
Urinary pH measurement does not provide a reliable assessment of acid-base balance! On one hand, due to nutritional influences, urinary pH ranges between 5 and 8. On the other hand, 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 always have to eat the same food and to 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.
The method developed by Friedrich Sander (urine pH)
The method developed in the 1930s 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 pH measurement method.
The method developed by Jörgensen and Stirum
This method determines the buffer capacity of the blood. Information can be obtained about the buffer capacity of red blood cells and hence about the possible degree of acidosis within the cells. This special blood analysis is used by special laboratories.