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Lab test

Sm/RNP Antibody Test

The Sm/RNP Antibody test measures Sm/U1-RNP antibody in a blood sample. Quest associates detection of this antibody with mixed connective tissue disease, a condition that can present with features of systemic lupus erythematosus, scleroderma and polymyositis.

Blood drawQuest patient service center

About this test

Sm/U1-RNP antibody is the marker this test reports, using a 1 mL serum sample analyzed by immunoassay. Quest ties its detection to mixed connective tissue disease, describing that condition as one that can share features with several other connective tissue conditions rather than presenting as a single distinct illness.

People who consider this test are usually being evaluated for a connective tissue condition where features overlap, since mixed connective tissue disease can resemble lupus, scleroderma or polymyositis. A clinician reads a result together with symptoms and other antibody tests, since Sm/U1-RNP antibody detection is one piece of that broader evaluation rather than a stand-alone answer.

Test details

Quest code38567
MethodologyImmunoassay
Sample type1 mL serum
CollectionQuest patient service center

Reference range

<1.0 Negative

Reference ranges are general guidance. The range printed on your own laboratory report is the one that applies to your result.

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Quest resources

Additional details

What this test looks at

The test reports a single result: the presence of Sm/U1-RNP antibody in serum. This is a separate product from the combined Sm and Sm/RNP Antibodies test, which reports Sm antibody and Sm/RNP antibody 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/RNP antibody test measure?

It measures the presence of Sm/U1-RNP 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.

What condition is Sm/RNP antibody associated with?

Quest associates detection of this antibody with mixed connective tissue disease, which can share features with systemic lupus erythematosus, scleroderma and polymyositis.

Is this the same as the Sm antibody test?

No. This product reports Sm/U1-RNP antibody only. A separate Quest product reports Sm antibody alone, and another reports Sm and Sm/RNP antibodies together.

What does a Sm/RNP Antibody test cost without insurance?

$200. Celio Health's price is a flat cash price and insurance is never billed: the required physician's order is included.

Last updated 2026-09-18 · How we write about lab testing

Educational content

This page is for general educational purposes only. It is not medical advice, and it is not a substitute for consultation with a qualified healthcare professional. Laboratory results should always be interpreted by a licensed clinician who knows your health history. If you have questions about your health or your results, talk with your doctor. If you think you may be experiencing a medical emergency, call 911.