• Fasting specimens are preferred

Fasting for a blood test

• Suggest discontinuing natalizumab at least 4 weeks prior to testing for eculizumab quantitation in serum

Red serum vial/tube, 5 mL

• Recommended timeframe for the blood collection is a trough, or immediately prior to next scheduled dose
• Immediately after specimen collection, place the tube on wet ice.

1. Allow specimen to clot while on wet ice
2. Spin at 4^◦ C in a refrigerated centrifuge
3. Transfer serum to a Screw cap transfer vial/tube (Mayo T465)
4. Freeze specimen within 30 minutes.

Screw cap transfer vial/tube (Mayo T465)

Frozen (preferred) - 28 days

Refrigerated - 28 days

Ambient - 28 days

• Gross hemolysis or lipemia
• Serum gel (SST) tubes

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

Eculizumab Complement Blockage:

> or =46% normal

Eculizumab:

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)