<qa>  What is the effect of vitamin D analogues?Many patients on haemodialysis will develop secondary hyperparathyroidism. Vitamin D analogues such as alphacalcidol are needed to bring their iPTH levels down to normal. However, these analogues can cause hypercalcaemia, thus its doses are limited by this effect. Cinacalcet, which is currently not widely available to patients in hospitals, is a calcimimetic that can reduce both iPTH and serum calcium levels. No studies have yet to be carried out investigating the outcome of using low doses of Cinacalcet as a means of optimizing doses of vitamin D analogues by keeping calcium levels from going over the upper limit. So a single arm, open-labelled study has been designed to determine the effectiveness of combination Cinacalcet with Vitamin D analogue in the treatment of severe hyperparathyroidism in patients with ESRF on haemodialysis. No formal sample size calculation was done as this is a proof of concept study. Power calculation will be done at the end based on the primary outcome of the study. 