All statistical analyses were performed using SPSS version 13.0(SPSS Inc., Chicago, IL). Data are expressed as mean (SEM). Variableswere tested for normality using the Kolmogorov–Smirnov statistic.Between group differences were analyzed by ANOVA with S–N–Kcorrection for multiple comparisons concerning continuous variablesand chi-square test for categorical variables, as appropriate. The areasunder the receiver operating characteristic (ROC) curves were used toestimate the power of serum calcium and the inhibition rate of PTH inthe calcium suppression test in order to differentiate the mild PHPTfrom the normal controls. The optimal cut-off point was calculated asthe maximum value of (sensitivity+specificity-1) [14]. Bivariatecorrelations were estimated using Spearman's correlation test.Pb0.05 was considered statistically significant and 95% confidenceintervals are presented.