Complement C1q, Quantitative

TEST: 016824
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CPT: 86160
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Special Instructions

State patient's sex on the request form.

Expected Turnaround Time

7 - 11 days

Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.

Related Documents

Specimen Requirements

Specimen

Serum

Volume

1 mL

Minimum Volume

0.1 mL (Note: This volume does not allow for repeat testing.)

Container

Red-top tube or gel-barrier tube

Collection

Separate serum from cells.

Storage Instructions

Room temperature

Stability Requirements

Temperature

Period

Room temperature

14 days

Refrigerated

14 days

Frozen

14 days

Freeze/thaw cycles

Stable x3

Causes for Rejection

Chylous or lipemic serum; hemolysis; gross bacterial contamination. Plasma should be avoided since fibrin may result in the appearance of nonspecific precipitation, which may adversely affect interpretation.

Test Details

Use

This test is used as an aid in the diagnosis and treatment of systemic lupus erythematosus (SLE).

Methodology

Radial immunodiffusion (RID)

Reference Interval

See table.

Age

Male (mg/dL)

Female (mg/dL)

0 to 1 y

Not established

Not established

2 to 5 y

9.8-18.5

9.7-19.1

6 to 17 y

10.2-19.6

10.2-19.4

>17 y

10.2-20.3

10.3-20.5

Additional Information

Serum levels of C1q are reduced in immune complex disease, SLE and meningitis. An undetectable C1q (a subunit of the first component of complement) in the presence of an absent total complement (CH50) and normal C2, C3 and C4 suggests a congenital deficiency. A low C1q in combination with a low C1 esterase inhibitor and low C4 suggests an acquired C1 esterase inhibitor deficiency.

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
016824 Complement C1q, Quantitative 4478-4 016824 Complement C1q, Quantitative mg/dL 4478-4

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The LOINC® codes are copyright © 1994-2021, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee. Permission is granted in perpetuity, without payment of license fees or royalties, to use, copy, or distribute the LOINC® codes for any commercial or non-commercial purpose, subject to the terms under the license agreement found at https://loinc.org/license/. Additional information regarding LOINC® codes can be found at LOINC.org, including the LOINC Manual, which can be downloaded at LOINC.org/downloads/files/LOINCManual.pdf