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Natural Killer Cells, Functional

Test Code


CPT Code(s)

88184, 88185 (x2)

Patient Preparation

Normal diet, fasting preferred to avoid lipemia

Preferred Specimen(s)

10 mL whole blood collected in a sodium heparin (green-top) tube

Minimum Volume

5 mL

Collection Instructions

Specimen must be received in the testing lab within 48 hours of collection. Submit Monday through Thursday only. Maintain and transport blood at room temperature. Avoid temperatures <15° C and >37° C. In hot weather, it may be necessary to pack the specimen in a container with insulating material around it and place this container inside another that contains a cold pack (ice pack) and absorbent material. This method will help retain the specimen at ambient temperature. For longitudinal studies, draw specimens at the same time of day to minimize diurnal variation.

Clients: Contact the lab prior to ordering for special logistics arrangements.

PSC: Follow short stability protocol. Test available by prior arrangement only. Special sample collection and transportation arrangements must be made prior to ordering the test. Contact your local customer service department and request to speak to someone in referral testing department for specific instructions. Submit Monday-Thursday only. Do not draw day before a holiday. Samples received >48 hours after collection will be rejected. Date and time of draw are required and must be provided.

Transport Container

Sodium heparin (green-top) tube

Transport Temperature

Room temperature

Specimen Stability

Room temperature: 48 hours
Refrigerated: Unacceptable
Frozen: Unacceptable

Reject Criteria

Hemolysis • Received refrigerated • Received frozen • Clotted specimens • Expired (>48 hours)


Flow Cytometry (FC)

This test was developed and its performance characteristics have been determined by Quest Diagnostics. Performance characteristics refer to the analytical performance of the test.

Performing Laboratory

Quest Diagnostics Nichols Institute-San Juan Capistrano, CA
33608 Ortega Highway
San Juan Capistrano, CA 92675-2042

Setup Schedule

Set up: Tues-Sat

Reference Range(s)

Decreased Activity <7 LU30
Normal Activity 7-125 LU30
Increased Activity >125 LU30

Clinical Significance

Natural killer cells (NK cells) are a subset of non-B, non-T peripheral blood lymphocytes that appear to play a crucial role in the human innate immune response. The function of NK cells is important for the clearance of tumor cells, for the removal of immunoglobulin-bound antigens, and for the control of viral infections. NK function has been reported to be decreased in certain individuals, including those with primary immunodeficiencies, those with late-stage human immunodeficiency virus infections, and pregnant women.

LOINC®' Code(s)

The Result and LOINC information listed below should not be used for electronic interface maintenance with Quest Diagnostics. Please contact the Quest Diagnostics Connectivity Help Desk for more information at 800-697-9302.

NOTE: The codes listed in the table below are not orderable Test Codes.

Result NameLOINC CodeComponent Name
85969340NATURAL KILLER CELLS, FUNCTIONAL34439-0Natural killer cell function

Reference ranges are provided as general guidance only. To interpret test results use the reference range in the laboratory report.

The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.

LOINC assignment is based on a combination of test attributes, including the method used by the performing laboratory. For tests not performed by Quest Diagnostics, codes are assigned by the performing laboratory.

* The tests listed by specialist are a select group of tests offered. For a complete list of Quest Diagnostics tests, please refer to our Directory of Services.