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Test ID ECULI Eculizumab, Serum

Ordering Guidance

Therapeutic drug monitoring of eculizumab may be useful when assessing response to therapy is difficult, or patients need to be above a certain therapeutic monoclonal antibody (mAb) concentration in order to improve the odds of a clinical response for therapy optimization, including potential dose de-escalation or discontinuation of therapy in remission states. Pharmacodynamic studies of complement blockage are also common, see ECUMP / Eculizumab Monitoring Panel, Serum for more information on related testing.

Specimen Required

Patient Preparation: Pembrolizumab/Keytruda must be discontinued at least 4 weeks prior to testing for eculizumab quantitation in serum.


Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

1. Collect blood immediately before next scheduled dose.

2. Centrifuge and aliquot serum into plastic vial within 2 hours of collection.

Useful For

Assessing the response to eculizumab therapy


Assessing the need for dose escalation


Evaluating the potential for dose de-escalation or discontinuation of therapy in remission states


Monitoring patients who need to be above a certain eculizumab concentration in order to improve the odds of a clinical response for therapy optimization

Method Name

Liquid Chromatography-Tandem Mass Spectrometry, High-Resolution Accurate Mass (LC-MS/MS HRAM)

Reporting Name

Eculizumab, S

Specimen Type


Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 28 days
  Frozen  30 days
  Ambient  4 days

Reference Values

Lower limit of quantitation =5.0 mcg/mL

>35 Therapeutic concentration for paroxysmal nocturnal hemoglobinuria (PNH)

>50 Therapeutic concentration for atypical hemolytic uremic syndrome (aHUS)

Day(s) Performed


Report Available

3 to 9 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
ECULI Eculizumab, S 90240-3


Result ID Test Result Name Result LOINC Value
65676 Eculizumab, S 90240-3


If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:

-Renal Diagnostics Test Request (T830)

-Coagulation Test Request (T753)

-Therapeutics Test Request (T831)