Okay, I'll give it a shot ...
In regards to a Hb of 7 and a Hct of 24, or a Hb 10 and Hct of 38:
What's wrong with these numbers?
Well, allow me to explain this phenomenon in terms of a blood transfusion. On average, one unit of packed cells (350 cc's of 65% Hct blood) will increase the Hct of an average person by about 3% or one Hb unit (gm/dL). However, you might notice that if you send a CBC immediately after the transfusion, the crit has actually gone up by 5-7%. That's because the components of the freshly transfused blood haven't had a chance to equilibrate with the intravascular and extravascular compartments. Check the CBC a few hours later (assuming patient is stable and not actively bleeding), and the Hb will have in fact gone up by 1 unit and the Hct by 3%, (down from the 5 to 7% increase originally).
The reverse is also true. Take someone actively bleeding. We all know that if somebody is acutely bleeding and their Hct comes back at 42, it means that the blood loss has been so rapid that the intravascular volume hasn't been able to replenish itself by mobilizing fluid from extravascular stores (i.e. interstitium).
So, what's wrong with the numbers posted by Noyac? The Hb and Hct ratio is usually 1:3. If it's less (i.e. 1:4), then it means that there has been an acute and recent change in the quantity of red blood cells in the intravascular compartment, and the numbers have not had a chance to reflect that re-equilibration.
