Abstract: The invention relates in particular to a method for detecting and/or quantifying cell-free DNA from a sample of biological fluid of a patient of interest, comprising at least: (i) a step of extracting cell-free DNA from a sample of biological fluid to which at least one effective quantity of a first exogenous DNA fragment having 50-2000 base pairs, preferably 50-200 base pairs, preferably 60-160 base pairs, even more preferably 70-150 base pairs and better still 80-140 base pairs (ICE), is added; (ii) a step of amplifying and quantifying the cell-free DNA extracted in step (i) and the exogenous DNA fragment ICE; and (iii) a step of standardising the amount of cell-free DNA extracted, comprising the calculation of a first ratio (Grewis) of the number of copies of cell-free DNA to the number of copies of the first fragment of exogenous DNA (ICE), and the uses thereof for the purpose of diagnosis, prognosis or theragnosis, or for monitoring the progress of a specific physiological state of a patient of interest