Anabolic/androgenic steroids can cause a number of changes in the hematological system that affect blood clotting. This effect can be very variable, however. The therapeutic use of these drugs is known to increase plasmin, antithrombin III, and protein S levels, stimulate fibrinolysis (clot breakdown), and suppress clotting factors II, V, VII, and X. These changes all work to reduce clotting ability. Prescribing guidelines for anabolic/androgenic steroids warn of potential increases in prothrombin time, a measure of how long it takes for a blood clot to form. If prothrombin time increases too greatly, healing may be impaired. The effects of anabolic/androgenic steroids on prothrombin time are generally of no clinical significance to healthy individuals using these drugs in therapeutic dosages. Patients taking anticoagulants (blood thinners), however, could be adversely affected by their use.
Conversely, anabolic/androgenic steroid abuse has been linked to increases in blood clotting ability. These drugs can elevate levels of thrombin and C-reactive protein, as well as thromboxane A2 receptor density, which can support platelet aggregation and the formation of blood clots. Studies of steroid users have demonstrated statistically significant increases in platelet aggregation values in some subjects. There are also a growing number of case reports where (sometimes fatal) blood clots, embolisms, and stokes have occurred in steroid abusers. Although it has been difficult to conclusively link these events directly to steroid abuse, the adverse effects of anabolic steroids on components of the blood coagulation system are well understood. These serious adverse effects are now regarded as recognized risks of steroid abuse among many that study these drugs.
In therapeutic levels, the anti-thrombic effects of anabolic/androgenic steroids seem to dominate physiology, and decreases in blood clotting ability may be noted. At a certain supratherapeutic dosage point, however, the pro-thrombic changes appear to overtake the anti-thrombic changes, and physiology begins to favor fast and abnormally thick clot formation (hypercoagulability). The exact dosage threshold or conditions required to increase blood clotting has not been determined, and some studies with steroid users taking supraphysiological doses fail to demonstrate increased coagulability. Individuals remain warned of the potential increases in thrombic risk with anabolic/androgenic steroid abuse. Blood clotting tendency should return to the pretreated state after the discontinuance of anabolic/androgenic steroids. 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