DIAGNOSTIC TEST 997

Beta Amyloid Ratio 42/40

Diagnostic test for Ratio Aβ42/40. For memory investigation, Alzheimer's disease.

Indication

Suspicion of Alzheimer's disease and in memory investigation

Sample material

CSF

  • Minim. volume: 0,5 mL

Transport

  • Within Sweden: frozen
  • International: frozen

Method

Chemiluminescence enzyme immunoassay (CELEIA)

Reference interval

>0.72 (≥ 50 years)

Result

Results are reported as a ratio.

Interpretation

When beta-Amyloid 42 aggregates in plaques, the ratio of beta-Amyloid 42/40 in CSF decreases. Decreased ratio can be found in early stages of Alzheimer's disease and can also be seen without evident cognitive impairment.

References

  • Hansson O et al. Alzheimers Res Ther. 2019. Advantages and disadvantages of the use of the CSF Amyloid β (Aβ) 42/40 ratio in the diagnosis of Alzheimer's Disease. PMID: 31010420
  • Dumurgier J et al. Alzheimers Res Ther. 2015. Cerebrospinal fluid amyloid-β 42/40 ratio in clinical setting of memory centers: a multicentric study. PMID: 26034513
  • Woyk K et al. J Alzheimers Dis Rep. 2025. The relationship of 18F-FDG-PET to other common biomarkers of dementia in a clinical cohort with memory deficits. PMID: 40290782
  • Amft M et al. Alzheimers Res Ther. 2022. The cerebrospinal fluid biomarker ratio Aβ42/40 identifies amyloid positron emission tomography positivity better than Aβ42 alone in a heterogeneous memory clinic cohort. PMID: 35473631
  • Martino-Adami PV et al. Lancet Reg Health Eur. 2024. Prognostic value of Alzheimer's disease plasma biomarkers in the oldest-old: a prospective primary care-based study. PMID: 39253733
  • Jack CR Jr et al. Alzheimers Dement. 2024. Revised criteria for diagnosis and staging of Alzheimer's disease: Alzheimer's Association Workgroup. PMID: 38934362

Included in these panels

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How to order

This test is available worldwide for hospitals, clinics, and physicians.

  1. Print and complete the request form

    Download the request form. Clearly state the name and phone number of the referring hospital, clinic, or physician.

  2. Prepare your samples

    CSF: At least 0.5 mL CSF (polypropylene tubes).

  3. Send samples and request form

    Within Sweden
    Send samples frozen to:
    Envelopes and smaller boxes:
    Wieslab AB, Box 50117, 20211 Malmö, Sweden

    Larger boxes and frozen samples:
    Wieslab AB, Lundavägen 151, 21224 Malmö, Sweden

    International
    Send samples frozen to:
    Wieslab AB, Lundavägen 151, 21224 Malmö, Sweden

Read our sampling instructions for more information

Last updated: 2025-12-05