Improved blood diagnostic

A method to quantify the abundance of Neurofilament light chain (NFL) in a blood sample, comprising the steps of supplementing to the said blood sample a composition comprising a polyanionic molecule and of reacting the said supplemented blood sample with at least one antibody, or a fragment thereof, coupled to a detection system, wherein the said polyanionic molecule has a molecular wight comprised between 5000 and 2000000 Da, and a charge density comprised between 1 and 20 negative charges per 1000 Da at a pH of 7, wherein the said polyanionic molecule is present in the supplemented blood sample in an amount between 0.01 wt % and 10 wt %, preferably between 0.1 wt % and 5 wt %, more preferably between 0.5 wt % and 1 wt % (weight polyanionic molecule:

• weight of the blood sample after supplementation), and wherein the said antibody, or the said antibody fragment, coupled to a detection system specifically binds to one epitope of the said NFL.