may i make an educated guess about the patient's albumin and phosphate?
The short answer is: YES
BUT the long answer is:
These components are often not routinely measured.
Both together constitute the bulk of the "weak acids", with albumin usually being the dominant one. In cases of severe hyperphosphataemia, as in severe untreated
renal insufficiency, the negative charge of phosphate can be bigger, though.
If you didn't specify a value, our programme assumes a normal phosphate, when calculating,
as this usually will not make much of a difference - an error of 2mEq/l at most, except for cases of severe hyperphosphataemia, where these values can be much higher than 10mEq/l.
albumin, though, is different, it typically contributes about 10mEq/l of negative charges.
A good rule of thumb is to calculate 1mEq/l negative charge per 4g/l albumin (or 0,4g/dl or 1,5mmol/l).
Most critically ill patients rapidly develop a pronounced hypalbuminaemia, so after a day or two of being
critically ill they tend to have values of about half the normal range. You can also take a lead from their
serum calcium levels. most blood gas machines report free ("ionised") calcium, while the lab report uses to give
total calcium. The lower the difference between the two is, the lower is the patient's albumin bound to be.
BEWARE THOUGH, A GUESS IS ALWAYS BUT A GUESS! So take the results with a grain of salt,
if what you just did, was guessing!
consult the glossary for other aspects of acid-base equilibria and the rules and mathematics behind our website: