PTH and rickets: However, both patients had recently started supplementation with cholecalciferol for hypovitaminosis D and in both cases repeated PTH after some months of adequate 25OHD3 levels resulted in the reference range, thus confirming their hyperparathyroidism to be secondary to hypovitaminosis D. In 2/31 cases (6.4%) TmP/GFR was below the reference range, thus indicating renal phosphate wasting.