Table 4: Analysis of the parameters of diagnostic efficiency of the RF according to the reference values. The first 60 U/mL is recommended by the reagent supplier, the second 18 U/mL is obtained from the 97.5 percentile from the average obtained in a population of 150 healthy individuals, and the third 12.5 U/mL corresponds to the mean ± two standard deviations of the results obtained in the same population. The results are expressed in percentages.