Diagnosis associated with Tau higher than 1200\u202fpg/mL: Insights from the clinical and laboratory practice.

Abstract

CONTEXT\nCerebrospinal fluid (CSF) biomarkers are valuable tools for the diagnosis of neurological diseases. We aimed to investigate within a retrospective multicentric study the final diagnosis associated with very high CSF Tau levels and to identify patterns of biomarkers that would differentiate them in clinical practice, to help clinical biologists into physicians counseling.\n\n\nPATIENTS AND METHODS\nWithin the national multicentric network ePLM, we included 1743 patients from January 1, 2008, to December 31, 2013, with CSF biomarkers assayed by the same Innotest assays (protein Tau, phospho-Tau [pTau], and Aβ 1-42). We identified 205 patients with protein Tau concentration higher than 1200\u202fpg/mL and final diagnosis.\n\n\nRESULTS\nAmong those patients, 105 (51.2%) were suffering from Alzheimer s disease, 37 (18%) from sporadic Creuztfeldt-Jakob disease, and 63 (30.7%) from other neurological diseases including paraneoplastic/ central nervous system tumor, frontotemporal dementia, other diagnoses, amyloid angiopathy, Lewy body dementia, and infections of the central nervous system. Phospho-Tau, Aβ1-42 and Aβ1-42/pTau values differed significantly between the three groups of patients (p\u202f<\u202f.001). An Aβ1-42/pTau ratio between 4.7 and 9.7 was suggestive of other neurological diseases (threshold in AD: 8.3). CSF 14-3-3 was useful to discriminate Alzheimer s disease from Creuztfeldt-Jakob disease in case of Aβ1-42 concentrations <550\u202fpg/mL or pTau>60\u202fpg/mL.\n\n\nCONCLUSION\nThis work emphasizes the interest of a well-thought-out interpretation of CSF biomarkers in neurological diseases, particularly in the case of high Tau protein concentrations in the CSF.