Why can’t a single blood test show you all the information you need instead of having to take multiple tests for different markers?

145 views
0

Why can’t a single blood test show you all the information you need instead of having to take multiple tests for different markers?

In: Biology

[removed]

A lot of blood tests needs the sample to be prepared in a specific way. All blood needs preparation in some way to avoid it coagulating in the test tube. But this might damage some of the things they are looking for. If you pay attention the next time you get your blood drawn you may notice that the test tubes they use are not completely empty but have a tiny droplet of something in them. This is what gets mixed with the blood as it is drawn. And different tests need different things to prepare the blood sample.

A blood test looks at the number of molecules or ions in a specified volume of blood.

To get this information, you need to mix the blood with different chemicals to draw them out before processing them. This is why different blood bottles exist, because mixing with the wrong ‘reagent’ will produce errors.

Even the most basic (common, not necessarily easiest) blood test like kidney function is still looking for four things: urea, creatinine, sodium and potassium. They all get processed off the same bottle helpfully, but if you wanted to do a full blood count (haemoglobin, white cells etc etc) that’s a different bottle and will give you upwards of 8 different numbers depending on the lab.

TL:DR – most blood tests are actually lots of results rolled into a list. There a far too many things in the blood to look for everything every time, it would cost tons.

Because we usually don’t need all. And getting them all would just be a burden on the individual. But there are times when we do them collectively in one blood sample. Such as post-partum (delivery) bleeding. We draw a single large enough sample for 5 different tests.

[removed]