Lab test · Immunology
Complement C3
Immune system activity (lupus)
- Blood sample
- No fasting
- Report within 2 days
- Home collection
What this test is for
Immune system activity (lupus)
Complement C3 is one of a group of proteins in the blood that help the immune system fight infection and clear away damaged cells. When the immune system is very active, as in lupus flares or some kinds of kidney inflammation, C3 can be used up faster than it is made and its level falls. Doctors use the C3 level to help diagnose these conditions and to follow how active they are.
Why a doctor may order it
- To help assess lupus and follow how active it is
- When blood or protein in the urine suggests inflammation of the kidneys
- Together with anti-dsDNA, to monitor lupus over time
- To investigate repeated or unusual infections
How to prepare
Fasting: Not needed.
There is no need to fast, and you can eat and drink as usual. Keep taking your usual medicines, including any treatment for lupus or kidney disease, unless your doctor says otherwise. Bring earlier C3 results if you have them, as the trend over time is often more useful than a single value.
At home
- Sample
- Blood sample
- How it works
- At your home, the collector cleans the skin, takes a small sample of blood from a vein in the arm and presses a cotton pad on the spot. It takes a few minutes.
- Report
- Within 2 days of collection.
What the results can mean
Your report shows the C3 level next to the laboratory's reference range. A low C3 can suggest active lupus, some types of kidney inflammation or, less often, an inherited complement problem. C3 can rise with infection or inflammation, as the body makes more of it at these times. Your doctor will interpret the level with your symptoms and other tests, often including anti-dsDNA and urine tests.
What's included
One test: Complement C3, from one blood sample.
Related tests
- Antinuclear Antibodies (ANA)Autoimmune disease screen (lupus)৳550
- Anti-dsDNA AntibodyThis blood test measures antibodies against double-stranded DNA, the genetic material inside the cell nucleus.
- Urine Routine Examination (Urine R/E)A urine routine examination, also called urinalysis, looks at your urine in three ways: its appearance, its chemistry (such as protein, sugar and acidity) and, under a microscope, any cells, crystals or bacteria.
- Kidney Function Test (RFT)A kidney function test, also called a renal function test (RFT), is a group of blood tests that show how well your kidneys are filtering waste from the blood.
- Rheumatoid Factor (RF)Rheumatoid arthritis check৳430
Questions people ask
Why is C3 low in lupus?
In active lupus, immune complexes form and use up complement proteins faster than the body can replace them. A falling C3 can be a sign that lupus is becoming more active.
Is C3 usually tested with C4?
Often, yes. C3 and C4 are both complement proteins, and doctors commonly look at them together. Ask your doctor whether you also need C4 measured.
Can a normal C3 rule out lupus?
No. C3 can be normal in lupus, especially when the disease is quiet. It is one piece of information that your doctor puts together with symptoms and other tests.
How much does a C3 test cost in Dhaka?
With Mukti Health the price is ৳750, and the sample is collected at your home in Dhaka. You see the price again before you confirm the booking in the Mukti Health app.
Can I do the C3 test at home in Dhaka?
Yes. Book it in the Mukti Health app and a trained sample collector comes to your home in Dhaka to take the blood sample. You do not need to go to a laboratory.
How long does the C3 report take?
The report is usually ready within 2 days of the sample being collected.