PTH and Hypercalcemia: The major role of PTH may be attributed to its well‐established, multiple direct physiologic effects on calcium metabolism, including enhanced gastrointestinal absorption and bone resorption, as well as inhibited renal excretion.(12, 13) However, PTH induced a rise in 1,25(OH)D via accelerated conversion of 25OHD; this may also be a minor contributor to hypercalcemia because calcium absorption by the gut and the kidneys is facilitated by 1,25(OH)D.