Blood is Thicker than Water

I took a few laboratory tests yesterday morning (13 Feb) and the results arrived promptly that afternoon. There are perhaps some interesting findings to me.

It's a pretty long list. Everything falls within the stated reference ranges. Yet reference ranges are a collection of values of which 95% of the normal population falls within. A quick search online and one will come across a variety of reference ranges for different parameters of the FBC. And that's where I've noticed some queer results.

It seems that my Haemoglobin, Packed Cell Volume and Red Blood Cell count is on the lower side of the normal range. Previously, I had expected that the volume of running I did would have required my body to produce more Hb (under stimulation by endogenous Erythropoietin) to counteract relative hypoxia induced by running. Therefore, I was rather puzzled with these findings whereby my Hb, PCV and RBC were on the lower end of the reference ranges.

After some reading, it seems like my understanding was correct, yet incomplete. It is indeed accurate that EPO does indeed increase under hypoxic exercise, stimulating RBC production. However, a dilutional pseudoanaemia may occur when undertaking high volume endurance training. In such an instance, RBC counts increase, but plasma volume increases at a faster rate than the former. This results in a lowering of Hb, PCV and RBC counts per unit volume. Note however, that this is due to a greater than proportionate increase in total plasma volume. Overall, exercise still results in an increase in absolute values of Hb and RBC. 

There is however, an unfortunate catch. Exercise may actually increase the rate of haemolysis due to mechanical rupture that occurs when RBCs pass through capillaries (circulatory trauma) in contracting muscles and compression of cells (footstrike haemolysis). Last but not least, minute amounts of iron (a requirement for the production of Hb) is lost through perspiration. 

What does this mean for me? I may hypothesize that my Hb, PCV and RBC counts are on the lower end of the reference due to dilutional pseudoanaemia. Unfortunately, my rate oh haemolysis is also likely to be increased. I suppose that what I need to ensure is progressive loading and proper nutrition and recovery to ensuring that I remain (assuming I already am) healthy.

Indeed, blood is thicker than water. Yet mine may be a little thinner than others'.