Which is not a component of MELD score

Recently, the Child-Pugh system has been replaced by the Model for End-Stage Liver Disease (MELD) system for the latter purpose. The MELD score is a prospectively derived system designed to predict the prognosis of patients with liver disease and poal hypeension. This score is calculated from three noninvasive variables: the prothrombin time expressed as the international normalized ratio (INR), the serum bilirubin level, and the serum creatinine concentration.Ref: Harrison&;s Textbook of Internal Medicine; 19th edition; Chapter 357; Approach to the Patient with Liver Disease; Page no: 1993