Decreasing the misdiagnosis of Alzheimer's disease patients

Beta-amyloid 42 (Ab42) in cerebral spinal fluid (CSF) is a biomarker of Alzheimer’s disease pathology. Decreased concentrations of Ab42 are suggestive of the presence of increased amyloid plaque deposition in the brain, which is consistent with this disease. Ab42 is easily adsorbed into commonly utilized lumbar puncture polystyrene tubes. A falsely low Ab42, due to incorrect sample collection, may contribute to misdiagnosis of patients.

A custom tube to prevent adsorption

At Mayo Clinic Laboratories, we require a specific polypropylene low-binding tube. In clinical studies, this tube has been most effective in preventing Ab42 adsorption and can provide more accurate results for patients.

Specimen instructions

Patient Preparation: For 12 hours before this test do not take multivitamins or dietary supplements containing biotin (vitamin B7), which is commonly found in hair, skin, and nail supplements and multivitamins.

Collection Container/Tube: CSF AD Biomarker Tube; specimens not collected in this tube will be rejected.

Specimen Volume: 2 mL

Collection instructions

1. Perform lumbar puncture and discard the first 1 to 2 mL of CSF.
2. Collect 2 mL of CSF directly into CSF AD Biomarker Tube. Do not aliquot. Analysis needs to be performed using collection tube.
   • Protocol recommends using drip method vs. syringe pull method.
3. Refrigerated (preferred) and send to Mayo Clinic Laboratories.
   • Frozen and Ambient are also accepted when following specimen stability requirements.