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Test Directory

Test Directory SM & RNP Antibodies

SM & RNP Antibodies

Test Summary

Antibodies to Sm are highly specific for systemic lupus erythematosus (SLE) and when present are considered a marker antibody. However, these antibodies are found in only 20% of patients with SLE. RNP antibodies (also known as anti-u1 or ribonucleoprotein antibodies) are found in 45% of SLE patients but are also observed in numerous other disease states such as Sjögren's syndrome, scleroderma and polymyositis. Elevated levels of antibodies to RNP are seen in mixed connective tissue disease. In SLE, RNP antibodies have been associated with a relatively benign disease course with lower incidence of renal and central nervous system involvement. Patients may be considered positive for RNP antibodies when the RNP antibody result is significantly higher than the SM antibody result.

Aliases

Anti-ENA
Anti-RNP: Anti-Smith ABS
Anti-Smith Antibody
ENA
ENA Antibodies
ENA Screen
RNP Antibody
SM &
RNP Antibodies
Smith Abs

Specimen Collection

Special Instructions

N/A

Preferred Specimen

1 mL serum (minimum 0.5 mL)

Minimum Volume

0.5 mL

Instructions

SST or Red top: Avoid hemolysis. Invert a minimum of 5 times, then allow to clot in an upright position for 30 minutes. Centrifuge the tube for at least 10 minutes. Keep tightly stoppered.

Patient Preparation

N/A

Storage

SST (speckled top), Red top , Plastic Vial (transfer) tube

Transport Temperature

Refrigerated (preferred)

Specimen Stability

Room Temperature = n/a
Refrigerated = 5 days
Frozen = at least 7 days

Limitations

N/A

Other Acceptable Specimens

N/A

Unacceptable Specimens

N/A

Order Code

SMRNP

EPIC (Premier) Code

LAB717

Includes

N/A

CPT Code

86235(2)

Billing Code

500339

CPT Statement

Methodology

Enzyme Immunoassay (EIA)

FDA Status

FDA Approved

Physician Attestation of Informed Consent

N/A

Testing Laboratory

CompuNet Clinical Laboratories, LLC
2308 Sandridge Drive
Moraine OH, 45439

Department

Molecular/Serology

Reference Range

	SEX	AGE	Report Normals
SM Antibody	N/M/F	1000Y	< 20 = Negative
			> = 20 = Positive
	Values between 20 and 40 are weak positives and repeat testing is recommended in 3 - 6 months.
	The presence of SM Antibodies is highly specific but relatively insensitive for SLE. SM Antibodies reactivity is not definitively described in other diseases, although a few studies describe them in Monoclonal Gammopathy, Schizophrenia and Uveitis.
RNP Antibody	N/M/F	1000Y	< 20 = Negative
			> = 20 = Positive
	Values between 20 and 40 are weak positives and repeat testing is recommended in 3 - 6 months.
	RNP antibodies are found in Mixed Connective Tissue Disease (MCTD), SLE, RA, Sjogren's Syndrome, Progressive Systemic Sclerosis, and drug induced LE. The presence of RNP Antibodies and the absence of SM and DS DNA Antibodies strongly suggest MCTD, while the absence of RNP usually rules out MCTD.

Setup Schedule / Expected Turnaround Time

Monday, Wednesday, Friday; BS; Reports available: 3 days