Why dont we use clotted blood for Hb estimation?

Question

Why dont we use clotted blood for Hb estimation?

Answer 1

I think the main reason is that the clot ties up all the red blood cells and as a result, one can not really assess the amount of hemoglobin in the clot -- one just has this mass of chemicals without any precise idea of how much hemoglobin is present. With a heparinized sample, the blood cells can be lysed (broken up) and the hemoglobin contained therein can be quantified.

I hate to take issue with John who is probably a lot smarter than I am.

Whoops! Thank you MajorMom for your correction!

Answer 2

With practically all the hemoglobin in the clot and almost none in the serum, what would it gain you? It would simply give you a clinically irrelevant number you already know.

Answer 3

Well, Gardener, I have take issue with one of your points! LOL!

EDTA is the anticoagulant used for hematology studies, not heparin.

To answer the question more specifically, hemoglobin is expressed as grams of hemoglobin per cubic millimeter of whole blood.  If you don't use whole blood, then the hemoglobin value is a nonsense answer and has no medical value/significance.