The PDIN balance (g/d) was the best independent variable to explain MUL variation (R2 = 0.950,CV=9.74).The regression between MUL and PDIN balance(%) is shown in Fig. 1. The intercept (22.9mg/dL) of this regression represents the predicted MUL value when PDIN balance is null. This predicted value is lower than the minimum value of the range (28–32mg/dL ) suggested by Brun-Bellut et al.(1991). Using the equation describing the relationship between MUL and PDIN balance(%), when MUL is 28mg/dL, the estimated PDIN balance is nearby+15%.