PTH and Hypocalcemia: 1,25(OH)2D3 and its analogues are considered to be appropriate only for the treatment of severe and progressive hyperparathyroidism and for patients with progressively elevated parathyroid hormone levels or consistently above the normal upper limit should be assessed for hyperphosphoemia, a high-phosphorus diet, hypocalcemia, and vitamin D deficiency for individualized treatment (KDIGO, 2017).