C3 deficiency is a rare inherited immune disorder characterized by extremely low levels of complement component C3, a critical protein in the immune system. It is caused by genetic mutations that prevent normal production or function of the C3 protein, leaving the body unable to effectively fight bacterial infections. The Complement Component C3c and C4c blood test is the most important test for diagnosis because it directly measures C3 levels in the blood.
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C3 deficiency is caused by inherited genetic mutations that affect the production or function of complement component C3, a crucial protein in the immune system. These mutations are typically autosomal recessive, meaning a person must inherit a defective gene from both parents to develop the condition. When C3 protein is absent or significantly reduced, the complement system cannot properly identify and eliminate harmful bacteria, making the body highly vulnerable to severe and recurrent bacterial infections, particularly from encapsulated bacteria like Streptococcus pneumoniae and Haemophilus influenzae.
The Complement Component C3c and C4c test is the most important test for C3 deficiency because it directly measures the levels of these critical complement proteins in your blood. In people with C3 deficiency, C3c levels will be significantly reduced or completely absent, providing clear diagnostic confirmation of this rare immune disorder. This blood test is essential because it distinguishes C3 deficiency from other complement deficiencies and immune disorders that may present with similar symptoms of recurrent infections. The test also measures C4c levels, which helps doctors understand whether other parts of the complement system are affected and guides appropriate treatment strategies.
You should get tested if you experience recurrent bacterial infections, especially pneumonia, meningitis, or severe sinus infections that keep coming back despite antibiotic treatment. Testing is particularly important if you have a family history of immune disorders or unexplained infections, if you were diagnosed with frequent infections as a child, or if your doctor suspects a complement system problem. Early diagnosis through blood testing is critical because it allows for prompt treatment with antibiotics and immunizations to prevent life-threatening infections and enables genetic counseling for family members who may be carriers of the mutation.
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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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