Erythrocytosis is when you have more red blood cells than normal. Red blood cells are also called erythrocytes. Red blood cells carry oxygen throughout your body and remove carbon dioxide from your body. Your bone marrow (the tissue inside your bones) makes red blood cells and releases them into your bloodstream.

What happens during erythrocytosis?

Erythrocytosis is a condition in which your body makes too many red blood cells (RBCs), or erythrocytes. RBCs carry oxygen to your organs and tissues. Having too many of these cells can make your blood thicker than normal and lead to blood clots and other complications.

Why does dehydration cause erythrocytosis?

Relative erythrocytosis generally results from hemoconcentration due to decreased fluid intake and/or marked loss of body fluids. A contraction of plasma volume produces the appearance of erythrocytosis without any actual increase in the body red cell mass.