Downstream systemic effects driven by elevated PTH may enhance renal conversion of 25OHD to [1,25(OH)2D] with subsequent suppression of 25OHD production in the skin and liver (2, 7), but the possibility that chronic 25OHD deficiency can itself initiate changes in parathyroid tissue that predispose to adenoma development and PHPT remains an open question. Here, PTH is linked to adenoma.