Objective To determine the correlation of tumor volume and weight with biochemical parame-ters in patients with parathyroid adenoma(PA).Methods A prospective electronic database collected clinical da-ta on 208 patients with PA treated for the first time by surgery at department of general surgery,Peking Union Medi-cal College Hospital,Chinese Academy of Medical Sciences & Peking Union Medical College.The relationship be-tween biochemical parameters and tumor volume and weight was analyzed with Spearman's correlation.Results Tumor volume and weight were positively correlated with parathyroid hormone(PTH)(r=0.33,P<0.001;r=0.39,P<0.001),calcium(r=0.16,P=0.018;r=0.18,P=0.007)and alkaline phosphatase levels(r=0.24,P<0.001;r=0.27,P<0.001),respectively.Clinical correlates affecting serum PTH were age,serum calcium and tumor weight(F=30.325,P<0.001).Conclusions Tumor burden in patients with PA correlates with some laboratory biochemical parameters.Age and cystic lesions of the tumor may influence the actual serum PTH levels.