Effectiveness and Safety of IV Zemplar in Patients on Hemodialysis and With Secondary Hyperparathyroidism Using iPTH/100 as Initial Dose

Inclusion Criteria: * Patients \>=18 years old with secondary hyperparathyroidism (PTH\>300pg/mL, measured in the last 2 weeks). * Patients on hemodialysis who require starting therapy with IV paricalcitol (de novo). * Patients attending 3 hemodialysis sessions per week. * Patients signing the informed consent approved by the Ethics Committee. If any individual is not capable of giving his/her consent, it can be obtained from a next of kin or from his/her legal representative, according to local laws and regulations. * The decision to initiate treatment is upon the investigator and the decision to treat patients with IV paricalcitol must not be based on the inclusion of the patient in the study or any other way. The decision to treat a patient with IV paricalcitol will be taken prior to asking the patient to participate in the study. Exclusion Criteria: * Patients with any concomitant clinical condition that, according to the investigator's opinion, might impede an adequate assessment of the treatment response. * Patients with severe hyperparathyroidism (PTH\>3000pg/mL). * Patients with a serum calcium level greater or equal to 10.5mg/dL, phosphorus greater or equal to 6.5mg/dL, or those with Calcium X Phosphorus product 65 (measured at least 2 weeks before the study). * Patients with neoplastic disease. * Pregnant or lactating women. * Known hypersensitivity and/or toxicity to vitamin D metabolites and/or to other ingredients of the product. * Having participated in another study with an investigational product or device within the previous 30 days or having planned to participate in another study within the same period of time as the actual study. * Use of vitamin D analogue during the last 3 months prior to the inclusion to this study.