thenumberslie - 10-7-2011 at 13:26
The body is a really cool complex symbiotic plethora of moving parts and living beings. It consumes complex foods like a steak, a tomato, to
"simpler" things as bread breaks them up, consumes what it can and eliminates the rest. Some levels through feces but what makes its way into the
blood stream makes it way to the kidneys and once the mighty magical kidney decides its waste its flushed on out.
What I don't understand is how urinalysis tests are developed. How is the urea, salts, creatinine and water separated out to leave the "urinary
metabolites" of what ever we consumed?
Mixell - 10-7-2011 at 13:32
May be they are not separated? Or at least not all of them.
There is a huge variety of indicators for what ever you want (or almost).
Ramiel - 10-7-2011 at 21:54
In a lab setting you will mostly find automated analysers which aspirate the sample and mix with reagent. On the analysers I've worked with the
electrolytes K, Na, Cl and sometimes lithium (although not usually tested for in urine) are measured with ion specific electrodes. Proteins (total
protein and albumin), creatinine and so on are bound by tailored immunoglobulins binding to the specific analyte. Then the level of Ig is measured,
either by turbidity or a reaction with something bound to the Ig. Other methods are simple chemical reactions, usually involving a chromophore in the
reagent.
Not all labs use the same methods, e.g. creatinine, and some methods have drawbacks e.g. high billirubin and wierd proteins can mess with the Jaffe
method for creatinine.
I have to go now, but can post more later if you wish.