Hi there
3 causes of hypercalacemia with detectable PTH level:
1. Primary hyperparathyroidism
2. Familial hypocalciuric hypercalcemia
3. Secondary hyperparathyroidism secondary to chronic hypocalcemia
Also in paraneoplastic syndromes in which hypercalcemia is due to PTH secretion or secretion pf PTH like substances
regards
Ash