DIAGNOSTIC TEST 987

pTau-181

Diagnostic test for pTau-181. For suspicion of Alzheimer's disease.

Important information – pTau217 replaces pTau181

During September 2026, the pTau181 assay will be discontinued from Wieslab’s routine portfolio and replaced with pTau217. The transition is expected to improve the clinical utility of blood-based biomarker testing for Alzheimer's disease.

There will be no changes to sample collection or shipment requirements for pTau217. Further information about this new test and updated request forms will be available on our website in September.

Indication

Suspicion of Alzheimer's disease or cognitive impairment.

Sample material

EDTA plasma

  • Minim. volume: 0,5 mL

Transport

Within Sweden

  • room temperature/frozen (stable for 48h at room temperature)

International

  • room temperature/frozen (stable for 48h at room temperature)

Method

Single Molecule Array (SIMOA)

Reference interval

< 45,0 pg/mL
The reference interval represents 99th-percentile of 150 healthy individuals.

Result

Results are reported as a concentration in pg/mL.

Interpretation

Plasma pTau-181 ≥ 45.0 pg/mL supports further investigations when Alzheimer's disease is suspected. The result should be combined with other investigations as well as clinical symptoms for the final diagnosis.

References

  • Querfurth HW, LaFerla FM. N Engl J Med. 2010. Alzheimer's disease. PMID: 20107219
  • Karikari TK et al. Lancet Neurol. 2020. Blood phosphorylated tau 181 as a biomarker for Alzheimer's disease: a diagnostic performance and prediction modelling study using data from four prospective cohorts. PMID: 32333900
  • Janelidze S et al. Nat Med. 2020. Plasma P-tau181 in Alzheimer's disease: relationship to other biomarkers, differential diagnosis, neuropathology and longitudinal progression to Alzheimer's dementia. PMID: 32123385
  • Liu HC et al. Dement Geriatr Cogn Dis Extra. 2020. Stability of Plasma Amyloid-β 1-40, Amyloid-β 1-42, and Total Tau Protein over Repeated Freeze/Thaw Cycles. PMID: 32308667
  • Thijssen EH et al. Lancet Neurol. 2021. Plasma phosphorylated tau 217 and phosphorylated tau 181 as biomarkers in Alzheimer's disease and frontotemporal lobar degeneration: a retrospective diagnostic performance study. PMID: 34418401
  • O'Connor A et al. Mol Psychiatry. 2021. Plasma phospho-tau181 in presymptomatic and symptomatic familial Alzheimer's disease: a longitudinal cohort study. PMID: 32665603

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. If you are a new customer, please also include a completed customer information form.

  2. Prepare your samples

    EDTA Plasma: At least 0.5 mL blood plasma (EDTA 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

Last updated: 2026-09-14