FDA-approved test expands options for Alzheimer's disease


Test in Focus

Mayo Clinic Laboratories will provide a new FDA-approved test for the assessment of amyloid pathology in Alzheimer's disease (AD) — while continuing to offer the laboratory's existing AD evaluation. In this "Test in Focus" episode of the "Answers From the Lab" podcast, Joshua Bornhorst, Ph.D., offers guidance on how the tests differ and when each might be appropriate to order.

"We want to provide options and flexibility for physicians," Dr. Bornhorst says. "The new test expands the offerings for the prospective Alzheimer's disease population, while we preserve the availability of testing that clinicians are familiar with."

Both the new AMYR test and the existing AD evaluation (Test ID: ADEVL) measure protein markers in cerebrospinal fluid. And both tests, which achieve greater than 94% concordance with positron emission tomography (PET) scans, are highly accurate.

But the tests also differ in several ways. AMYR is an FDA-approved evaluation, but is only currently approved for patients ages 55 and older. ADEVL can be ordered for all adults and is a CLIA-certified laboratory developed test, and has undergone extensive clinical validation at Mayo Clinic Laboratories.

Another difference is what the tests measure and how results are reported. ADEVL evaluates the p-tau181/Ab42 ratio while AMYR evaluates the Ab42/Ab40 ratio. AMYR yields three categories of results, indicating positive, likely positive, and negative findings of amyloid deposits. ADEVL reports only two results: positive or negative.

Listen to learn more about Mayo Clinic Laboratories' options for Alzheimer's disease testing.

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Testing

Useful information

AMYR | Beta-Amyloid Ratio (1-42/1-40), CSF

  • Assisting in the evaluation of adult patients, aged 55 years and older, presenting with cognitive impairment and who are being assessed for Alzheimer’s disease (AD) and other causes of cognitive decline. 
  • This test is not intended as a screening or stand-alone diagnostic assay.

ADEVL | Alzheimer Disease Evaluation, Spinal Fluid

  • Assessment of adults with cognitive impairment being evaluated for Alzheimer disease (AD) and other causes of cognitive impairment.
  • These assays should not be used to predict the development of dementia or other neurologic conditions or to monitor response to therapies.

Specimen requirements

AMYR | Beta-Amyloid Ratio (1-42/1-40), CSF

  • Specimen Type: Cerebrospinal fluid
  • Preferred: Sarstedt 1.5 mL tube (Ref. 72.703.600) Collect at least 750 μL of CSF or (>/=50% full).
  • Acceptable: 
    • Sarstedt 10 mL tube Ref. 62.610.018  Collect at least 5mL of CSF (>/=50% full).
    •  All tubes should be filled to between 50%-100% of the total empty container volume. Samples received with less than the required fill volume may be rejected.
  • Specimen Volume:  0.75 – 1.5 mL or at least 50% container volume
  • Collection Instructions:
    • This test is intended for use in adult patients, aged 55 years and older. Do not collect CSF for this test if the patient is not 55 years of age or older.
    • Perform lumbar puncture and discard the first 1 to 2 mL of cerebrospinal fluid (CSF). Note: CSF collection should be performed by the gravity drip method.
    • Discard any visibly blood contaminated CSF.
    • Collect CSF directly into one of the listed collection tubes until the tube is at least 50% full.
    • If transporting frozen, freeze sample upright prior to placing in transport container.
    • If transporting refrigerate, tubes should be transported upright.
  • Note: Polystyrene collection tubes are not acceptable. Exposure of CSF to polystyrene tubes may result in falsely low beta-Amyloid  concentrations. For more information see Cautions.

ADEVL | Alzheimer Disease Evaluation, Spinal Fluid

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

  • Specimen Type: CSF
  • Supplies:  Alzheimer's Disease Evaluation (ADEVL) Collection Kit (T836)
  • Acceptable: Sarstedt 72.703.600 (1.5 mL) or Sarstedt 72.694.600 (2 mL)
  • Specimen Volume:  1.5-2 mL
  • Collection Instructions:
    • Perform lumbar puncture and discard the first 1 to 2 mL of cerebrospinal fluid (CSF).
    • Collect CSF directly into one of the listed collection tubes until the tube is at least 50% full*.
  • Note: Polystyrene collection tubes are not acceptable. Exposure of CSF to polystyrene tubes may result in falsely low Abeta42 concentrations. For more information see Cautions. *The Alzheimer's Association consensus protocol for handling of CSF for clinical measurements of Abeta42 and tau recommends using the drip method for CSF collection and directly collecting into a low bind polypropylene tube. Although some clinicians prefer the syringe pull method due to speed of collection, the drip method reduces the risk of Abeta42 binding to the plastic of any syringe used.

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Barbara J. Toman (@barbaratoman)

Barbara J. Toman

Barbara J. Toman is a Senior Communications Specialist at Mayo Clinic Laboratories. She is also the science writer for Mayo’s Neurosciences Update newsletter, which helps referring physicians to stay informed about Mayo’s treatment and research. Barbara has worked at Mayo Clinic since 2007. She enjoys international travel and cooking.