PTH and hyperparathyroidism: On the other hand, PTH zscores show tendency of continuous cumulative increment across age groups that became significant with the start of adolescence (each p < 0.01 vs. groups A and B), and the prevalence of hyperparathyroidism increased steadily with age, reaching 14.3% in young children (group A), 27.3% in older children (group B), and 68.2% in adolescence (each p < 0.01; group C vs. groups A and B).