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HelpOrder Code RAVMP Ravulizumab Monitoring Panel, Serum
Ordering Guidance
To measure only serum concentration of ravulizumab, order RAVU / Ravulizumab, Serum.
Specimen Required
Patient Preparation:
1. Fasting: 8 hours, preferred but not required
2. Suggest discontinuing natalizumab at least 4 weeks before specimen collection for ravulizumab testing. Patient should consult the healthcare professional who prescribed this drug to determine if discontinuation is an option. If not, it is okay to proceed with testing while taking natalizumab.
Supplies: Aliquot Tube, 5 mL (T914)
Collection Container/Tube: Red top (serum gel/SST are not acceptable)
Submission Container/Tube: 2 Plastic vials
Specimen Volume: 2 mL Serum in 2 plastic vials, each vial containing 1 mL
Collection Instructions:
1. Draw blood immediately before next scheduled dose.
2. Immediately after specimen collection, place the tube on wet ice and allow specimen to clot.
3. Centrifuge at 4° C and aliquot serum into two 5 mL plastic vials.
4. Freeze serum within 30 minutes of centrifugation. Serum must be placed on dry ice if not frozen immediately.
NOTE: If a refrigerated centrifuge is not available, it is acceptable to use a room temperature centrifuge, provided the sample is kept on ice before centrifugation, and immediately afterward, the serum is aliquoted and frozen.
Useful For
Monitoring of complement blockage by ravulizumab
Assessing the response to ravulizumab therapy
Assessing the need for dose escalation
Evaluating the potential for dose deescalation or discontinuation of therapy in remission states
Monitoring patients who need to be above a certain ravulizumab concentration in order to improve the odds of a clinical response for therapy optimization
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| RAVU | Ravulizumab, S | Yes | Yes |
| RAVUM | Ravulizumab Complement Blockage, S | No | Yes |
| RAVIN | Ravulizumab Interpretation, S | No | Yes |
Method Name
RAVU: Liquid Chromatography Tandem Mass Spectrometry, High Resolution Accurate Mass (LC-MS/MS HRAM)
RAVUM: Enzyme-Linked Immunosorbent Assay (ELISA)
RAVIN: Technical Interpretation
Reporting Name
Ravulizumab Monitoring Panel, SSpecimen Type
SerumSerum Red
Specimen Minimum Volume
Serum: 1 mL in 2 plastic vials, each vial containing 0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Frozen | 14 days |
| Serum Red | Frozen | 14 days |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | OK |
Reference Values
RAVULIZUMAB:
Lower limit of quantitation =5.0 mcg/mL
>175 mcg/mL: Therapeutic concentration for paroxysmal nocturnal hemoglobinuria and atypical hemolytic uremic syndrome
RAVULIZUMAB COMPLEMENT BLOCKAGE:
≥46% Normal
Method Description
Monoclonal immunoglobulin rapid accurate mass measurement (miRAMM) is used to quantify intact light chains from the therapeutic monoclonal antibodies (mAb) in human serum. Briefly, IgG4 along with IgG4 monoclonal or therapeutics are extracted from patient sample using a human IgG4 affinity matrix that contains a 12-kDa llama antibody fragment recognizing human IgG4. Wash steps significantly reduce background and remove all non-IgG4s as well as other proteins from the sample. After elution, the mixture undergoes a reduction step to release the light chains from the heavy chains by reducing the disulfide bonds that keep them together. While full scan data is collected, targeted selected ion monitoring occurs for the +10, 11, and 12 charge states for the eculizumab/ravulizumab light chain along with the +11-charge state for natalizumab, the surrogate internal standard. Multiple isotopes of each charge state are combined to be used for quantitation. A standard curve of the pharmaceutical mAb spiked into normal human serum is used for quantitation.(Unpublished Mayo method)
The Wieslab enzyme-linked immunosorbent assay (ELISA) complement assay for the alternative pathway combines principles of the hemolytic assay for complement activation with the use of labeled antibodies specific for neoantigens produced as a result of complement activation. The microtiter plate strips are coated with lipopolysaccharide. Patient serum is diluted in diluent containing specific blocker to ensure that only the alternative pathway is activated. During the first incubation, the diluted patient serum in the wells is activated by the coating. The wells are then washed and C5b-9 (membrane attack complex: MAC) is detected with a specific alkaline phosphatase labeled antibody to the neoantigen expressed during MAC formation. After a final wash, an alkaline phosphatase substrate is added. The amount of alternative pathway complement activity correlates with the color intensity of the solution and is measured in terms of absorbance (optical density).(Nordin JG, Truedsson L, Sjoholm A. New procedure for detection of complement deficiency by ELISA. Analysis of activation pathways and circumvention of rheumatoid factor influence. J Immunol Methods. 1993;166[2]:263-270; Frazer-Abel A, Sepiashvili L, Mbughuni MM, Willrich MA. Overview of laboratory testing and clinical presentations of complement deficiencies and dysregulation. Adv Clin Chem. 2016;77:1-75. doi:10.1016/bs.acc.2016.06.001)
Day(s) Performed
Varies
Performing Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
80299
86161
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| RAVMP | Ravulizumab Monitoring Panel, S | 101923-1 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 609500 | Ravulizumab Complement Blockage, S | 74520-8 |
| 609420 | Ravulizumab, S | 97184-6 |
| 619952 | Ravulizumab Interpretation | 59462-2 |
Forms
If not ordering electronically, complete, print, and send a Coagulation Test Request (T753) with the specimen.