Elevated red blood cell counts are quite common among men who take injectable testosterone. It is most common among men taking injectable testosterone (67% of users) and less in those using non-injectable options (about 13%.) Most physicians become concerned over this elevation of hemoglobin and hematocrit and prescribe unnecessary treatment. In most cases, they associate and confuse this elevation with a blood condition called polycythemia vera, while the symptoms might better resemble a less harmful side-effect known as erythrocytosis. To help you understand the difference between the two, here is a brief overview of their effects on the body, and the common misconceptions associated with TOT. What Is Polycythemia? Polycythemia is a condition in which all blood cells are elevated, including platelets. Also known as polycythemia vera, polycythemia rubra vera, erythremia, Vaquez disease, and Osler-Vaquez disease, it is a stem cell disorder characterized as a panhyperplastic, malignant, and neoplastic marrow disorder. Its most prominent feature is an elevated absolute red blood cell mass because of uncontrolled red blood cell production. What Is Erythrocytosis? Erythrocytosis usually affects men who inject testosterone. The condition is an increase in the red blood cells due to the stimulation of hematopoietic growth factors from testosterone therapy. Serum testosterone levels are most related to erythrocytosis, rather than erythropoietin (EPO) levels in hypogonadal men. Depending on the dose, testosterone can increase the hemoglobin and hematocrit rate but does not rise in EPO. Key Difference The difference is that erythrocytosis only causes increased red blood cells and no harm. Polycythemia causes an increase in platelets, which causes increased clotting. It also associates with a defect in the blood vessel wall, which stimulates the clotting cascade of thrombosis. These two factors cause an increased risk of blood clots and strokes, thereby requiring treatment by phlebotomy or blood donation to lower blood counts and prevent the complications of polycythemia. Many physicians confuse erythrocytosis with polycythemia rubra vera, which can cause an increase in clotting and lead to strokes and heart attacks. How Does Testosterone Cause Erythropoiesis? Testosterone stimulates erythropoiesis through the production of hematopoietic growth factors and is suggested to act directly on bone marrow, specifically on the polychromatophilic erythroblast. It is a similar phenomenon that occurs when athletes use Epogen or Procrit to raise their blood count to enhance their endurance. It is also the same process that causes people who live at high altitude to have an increase in red blood cell counts. It is because it is a physiologic yet harmless increase in RBCs alone, not in any other cells or clotting factors. Erythropoiesis Occurs Naturally Treatment is not necessary for anyone with erythrocytosis that lives at high altitude, as it does not cause any problem whatsoever and is quite beneficial. The response is normal, expected, and not harmful for their blood to carry more oxygen. Over 400 million people worldwide live at high altitude and have high blood counts, and yet no treatment is necessary nor is there ever any harm. Athletes train at high altitude to raise their blood cell counts to increase their exercise endurance at sea level. Colorado has the 8th lowest mortality rate, the 3rd lowest cardiovascular rate in the US and the longest life expectancy at 87, despite having the highest average altitude and hematocrit rates. Get a copy of the TOT Bible and start your journey with a wealth of knowledge based on meticulous research, collaboration with the top physicians, medical innovations, and stories from real patients.