Complement C3
A core complement protein that drops when immune activity, especially lupus, is consuming it.
Consider this test if:
- Working up known or suspected lupus, with joint pain, rash, fatigue, or kidney involvement
- Monitoring a complement-consuming autoimmune condition for flares or treatment response
- Investigating unexplained glomerulonephritis or persistent kidney inflammation
- Recurrent serious bacterial infections that raise the question of an inherited complement deficiency
- HSA/FSA eligible
- Typical results in 1-2 days · Reviewed by a real clinician
- Drawn at a CLIA/CAP-accredited lab near you ·
Pre-test considerations
No fasting required and no specific timing. C3 rises with acute inflammation or infection, so a recent illness can push an otherwise low result into the normal range; note any active infection when interpreting the value.
Video consult with your Care Team
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What this test is for
Complement C3 is the most abundant protein in the complement system and sits at the center of both the classical and alternate immune pathways. Low C3 usually means complement is being consumed faster than it is made, which points to active immune disease: systemic lupus erythematosus (especially lupus nephritis), poststreptococcal and membranoproliferative glomerulonephritis, chronic active hepatitis, and certain chronic infections. High C3 is an acute-phase response and rises with inflammation generally. It is most informative paired with C4 and, in suspected lupus, with anti-dsDNA and ANA, and serial measurements track disease flares and response to treatment.
This is the standalone C3 measurement. If you want C3 and C4 together, the Complement C3c and C4c Panel covers both, and the Autoimmune Panel adds anti-dsDNA and ANA for a fuller lupus workup.
What to expect
- 1 Book instantly
Click, book, done. Choose a convenient lab location near you. Transparent, up-front pricing.
- 2 Quick lab visit
Testing to fit your busy schedule, usually 15 minutes or less. Walk-in and appointments available.
- 3 Typical results in 1-2 days
Your results post straight to your dashboard as soon as the lab completes them.
- 4 Expert guidance
Included with Mito membership. A clinician reviews your results and your personalized action plan follows, with clear next steps.
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Frequently asked questions
View all FAQsHow does pricing work?
Every test shows the member price next to the standard non-member price, so you can see what membership saves you. The member price is our cost — covering the lab and what it takes to run the service — never a profit on the test itself; Mito makes its money on the $9 membership, not on marking up your tests. Membership is $9/mo, and you still pay the lab’s order fee. Prices are itemized before you pay, with no hidden fees.
Where do I get tested?
Choose a partner lab (Quest, Labcorp, or BioReference) at checkout. If your cart spans multiple tests, we consolidate the whole order onto a single lab so you only make one visit.
Is this eligible for HSA/FSA?
Yes. This test is HSA/FSA eligible, and you can pay with your HSA/FSA card at checkout.
When will I get my results?
Your results post to your dashboard once your lab completes them, then a clinician reviews them and your full analysis and personalized action plan (with clear next steps) follow. Turnaround varies by test: specialty assays and at-home kits take longer, and each test shows its expected turnaround before you buy.
Do I need a doctor’s order?
No. Mito provides the lab order for you, so you can book and get tested without a separate doctor visit.
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