5 WARNINGS AND PRECAUTIONS5.1 HypercalcemiaHypercalcemia may occur during Paricalcitol Injection treatment. Acute hypercalcemia may increase the risk of cardiac arrhythmias and seizures and may potentiate the effect of digitalis on the heart [see Warnings and Precautions (5.2)]. Chronic hypercalcemia can lead to generalized vascular calcification and other soft-tissue calcification. Severe hypercalcemia may require emergency attention.Hypercalcemia may be exacerbated by concomitant administration of high doses of calcium-containing preparations, thiazide diuretics, or other vitamin D compounds [see Drug Interactions (7)]. In addition, high intake of calcium and phosphate concomitantly with vitamin D compounds may lead to hypercalciuria and hyperphosphatemia. Patients with a history of hypercalcemia prior to initiating therapy may be at increased risk for development of hypercalcemia with Paricalcitol Injection. In these circumstances, frequent serum calcium monitoring and Paricalcitol Injection dose adjustments may be required.When initiating Paricalcitol Injection or adjusting Paricalcitol Injection dose, measure serum calcium frequently (e.g., twice weekly). Once a maintenance dose has been established, measure serum calcium at least monthly. If hypercalcemia occurs, reduce the dose or discontinue Paricalcitol Injection until serum calcium is normal [see Dosage and Administration (2.2, 2.3)].Inform patients about the symptoms of elevated calcium (feeling tired, difficulty thinking clearly, loss of appetite, nausea, vomiting, constipation, increased thirst, increased urination, and weight loss) and instruct them to report new or worsening symptoms when they occur.5.2 Digitalis ToxicityParicalcitol Injection can cause hypercalcemia [see Warnings and Precautions (5.1)] which increases the risk of digitalis toxicity. In patients using Paricalcitol Injection concomitantly with digitalis compounds, monitor serum calcium and patients for signs and symptoms of digitalis toxicity. Increase the frequency of monitoring when initiating or adjusting the dose of Paricalcitol Injection [see Drug Interactions (7)].5.3 Adynamic Bone DiseaseAdynamic bone disease with subsequent increased risk of fractures may develop if intact PTH levels are suppressed by Paricalcitol Injection to abnormally low levels. Monitor intact PTH levels to avoid over suppression and adjust Paricalcitol Injection dose, if needed [see Dosage and Administration (2.2, 2.3)].