Antithrombin III deficiency is a hereditary blood clotting disorder that dramatically increases the risk of developing dangerous blood clots throughout the body. It is caused by insufficient production of antithrombin III protein, a natural anticoagulant that prevents excessive clot formation in blood vessels. The Antithrombin III Antigen test is the most important test for diagnosis because it directly measures the amount of this critical protein in your blood.
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Antithrombin III deficiency is caused by genetic mutations inherited from one or both parents that affect the production or function of antithrombin III protein. This protein normally acts as a natural blood thinner by blocking clotting factors in your blood, preventing clots from forming when they are not needed. When you have a deficiency, your blood lacks this protective mechanism, making it much more likely to form dangerous clots in your veins and arteries, particularly in the legs, lungs, and brain.
The Antithrombin III Antigen test is the most important test for diagnosing antithrombin III deficiency because it directly measures the actual amount of antithrombin protein circulating in your bloodstream. Low levels of this protein confirm the deficiency and help your doctor determine how severe your condition is. This test is especially valuable if you have experienced unexplained blood clots, have a family history of clotting disorders, or have had multiple miscarriages, as these are all signs that your body may not be producing enough of this critical anticoagulant protein.
You should get tested if you have experienced blood clots before age 50, have recurrent clots without obvious causes, have multiple family members with clotting problems, have had unexplained pregnancy losses, or developed a blood clot in an unusual location like your abdomen or brain. Testing is also recommended before starting birth control pills or hormone therapy if you have a family history of this deficiency, as these medications can significantly increase your clot risk when combined with antithrombin deficiency.
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What this means
Your testosterone levels are slightly below the optimal range. While this is not necessarily cause for concern, it may contribute to occasional fatigue, reduced motivation, or lower muscle mass over time.
Recommended actions
Increase resistance or strength training
Prioritize 7–8 hours of quality sleep per night, try to reduce stress
Include more zinc- and magnesium-rich foods (like shellfish, beef, pumpkin seeds, spinach)
Consider retesting in 3–6 months
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