Anabolic/androgenic steroids stimulate erythropoiesis (red blood cell production). One Anabolic/androgenic steroids stimulate erythropoiesis (red blood cell production). One potential adverse effect of this is polycythemia, or the overproduction of red blood cells. Polycythemia can be reflected in the hematocrit level, or the percentage of blood volume that is made up of red cells. As the hematocrit rises, so too does the viscosity of the blood. If the blood becomes too thick, its ability to circulate becomes impaired. This can greatly increase the risk of serious thrombic event including embolism and stroke. A high hematocrit level is also an independent risk factor for heart disease. The normal hematocrit level in men is 40.7 to 50.3%, and in women it is 36.1 to 44.3% (numbers may vary very slightly depending on the source). For the sake of scale, while a hematocrit of 50% may be normal, a hematocrit of 60% or above is considered critical (life threatening).
Anabolic/steroid administration tends to raise the hematocrit level by several percentage points, sometimes more. As a result, many steroid-using bodybuilders will have hematocrit levels that are above the normal range. For example, one study measured the average hematocrit in a group of steroid abusing competitive bodybuilders to be 55.7%. This level is considered clinically high, and would increase blood viscosity enough to raise the risk of serious cardiovascular event. Although not likely to be an isolated cause, high hematocrit is believed to have been a contributing factor in the deaths of a number of steroid abusers, usually paired with high blood pressure, homocysteine, and/or atherosclerosis. The average hematocrit level in bodybuilders not taking anabolic/androgenic steroids was 45.6%, well within the normal range for healthy adult men.
Many physicians that specialize in hormone replacement therapy consider a hematocrit level of 55% to be an absolute cutoff point. At or above this point, and anabolic/androgenic steroid therapy cannot be continued safely. Drug intake would be ceased at this point until the hematocrit issues have been corrected. Minor elevations in hematocrit may be addressed with phlebotomy. For this, 1 pint of blood may be removed periodically during steroid intake, often every two months. Proper hydration is also important, as dehydration can temporarily cause the hematocrit level to elevate, giving a false positive for polycythemia. The daily intake of aspirin is also commonly advised if the hematocrit is above normal, as this will reduce platelet aggregation, or the tendency for platelets to stick together and form clots. Individuals remain cautioned of the potential cardiovascular danger of high hematocrit levels associated with anabolic/androgenic steroid use.
Wlliam Llewellyn (2011) - Anabolics