PTH and chronic kidney disease: MANCOVA of the combined PTH 2G and PTH 3G as a dependent variable with 2 repeated measurements (at PTH T0 and PTH T10) showed a significant effect of preoperative calcium on IOPTH fall (p=0.007, effect size 0.110), with no significant effects of the other factors (age, sex, CKD-EPI-eGFR, BMI, and 25(OH)D) (Table 3).