Sm Antibody Test
The Sm Antibody test measures Smith (Sm) antibody in a blood sample. Quest describes Sm antibody as highly specific for systemic lupus erythematosus (SLE), though it is found in only a minority of people with the condition.
About this test
Sm antibody, also called Smith antibody, is one of the more specific markers clinicians use when evaluating for SLE. Quest reports that it is detected in about 15% of people with SLE overall, and in more than half of young African-American women with SLE, meaning its detection rate varies by population even though its specificity for the condition is high.
Who might consider this test?
- People who consider this test are usually being evaluated for lupus, often alongside other antibody tests such as Sm/RNP.
- Highly specific but not present in most people with SLE
- A negative result does not rule out the condition
Test details
| Quest code | 37923 |
|---|---|
| Methodology | Immunoassay |
| Sample type | 1 mL serum |
| Collection | Quest patient service center |
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Quest resources
Additional details
What this test looks at
The test reports a single result: the presence of Smith (Sm) antibody in serum. Quest also lists it under the alias Sm or Smith Antibody. It is a separate product from the combined Sm and Sm/RNP Antibodies test, which reports both antibodies together.
Order online and a physician order is included — no doctor's visit and no insurance needed. Your sample is collected at a Quest Diagnostics patient service center.
Laboratory results should always be interpreted by a licensed clinician who knows your health history. This page is information about a test, not medical advice.
Frequently asked questions
What does the Sm antibody test measure?
It measures the presence of Smith (Sm) antibody in a serum sample, using immunoassay methodology.
How is the sample collected?
The test uses a 1 mL serum sample from a routine blood draw.
Do I need to prepare for this test?
No preparation instructions are listed for this test, though people follow any instructions their ordering clinician provides.
How specific is Sm antibody for lupus?
Quest describes it as highly specific for SLE, though it is detected in only about 15% of people with SLE overall, and in more than half of young African-American women with SLE.
Is this the same as the Sm and Sm/RNP Antibodies test?
No. This product reports Sm antibody only. A separate Quest product reports Sm antibody and Sm/RNP antibody together.
How much does the Sm Antibody test cost?
The cash price at Celio Health is $200. That covers the physician's order and sample collection at a Quest patient service center — no insurance is needed and there's no separate doctor's visit to pay for.