Cinacalcet in Paediatric Secondary Hyperparathyroidism (SHPT) Due to Chronic Kidney Disease (CKD)

Inclusion Criteria: * Parents'/guardian written informed consent, and child's assent * Age \> 2 and \<18 years; * A dry body weight (BW) \>10.49 Kg in males and \>9.95 Kg in females, respectively; * Inpatient or outpatient status at the time of enrolment; * Males or females. Female subjects sexually active must be neither pregnant nor breastfeeding, and must lack childbearing potential from screening visit to the end of the safety follow-up * On stable hemodialysis (HD) or peritoneal dialysis (PD) for their CKD for at least one month before entering the 6-month pre-treatment period; * Plasma iPTH levels \> 300 pg/mL, AND * Plasma Ca levels \> 9.4 mg/dL (with normal serum albumin level), AND * Plasma P levels \<6.5 mg/dL in patients younger than 6 years, or \<6.0mg/dL in older patients, OR * Ca x P product \> 60; * Records' availability for the following parameters 6 months prior to study entry: demographic information, physical examination, height and dry weight, auxological/anthropometric indices, blood pressure values, Kt/V urea, plasma iPTH, calcium, phosphorus, and alkaline phosphatise levels, blood pH and bicarbonate, serum creatinine/urea, C reactive protein (CRP) levels, liver function tests, blood count, blood 25(OH) vitamin D3 level. Exclusion Criteria: * The following laboratory values: Hb\<9.0 g/dL, WBC\<2000/mm3 (2x109/L), platelets \<150,000/mm3 (150x109/L) only in subjects who are otherwise eligible for PK/PD assessments; abnormal liver function, defined by a total bilirubin ≥2 times the upper limit of normal values, ASAT, ALAT, γ-GT levels ≥2 times the ULN values. * Any other lab values that in the opinion of the investigator might place the subject at unacceptable risk for participation in the study. * History of malignancy (active malignancy, or off therapy since less than 1 year) * History of diseases causing hypercalcemia * Chronic inflammatory diseases (C-Reactive Protein-CRP \>2 times the upper limit of normal values) requiring a concomitant corticosteroid or immunosuppressive therapy * History of infectious diseases (including opportunistic infections) within 4 weeks prior to study entry * Evidence as assessed by the Investigator of active or latent bacterial, viral or fungal infections at the time of potential enrollment, including subjects with evidence of HIV infection. * Hepatitis-B surface antigen-positive subjects only in subjects who are otherwise eligible for PK/PD assessments * Hepatitis C antibody-positive subjects who are also PCR-positive or RIBA positive only in subjects who are otherwise eligible for PK/PD assessments * Use of recombinant human growth hormone therapy * Use of drugs that interact with cinacalcet disposition * Previous use of cinacalcet