This is a pilot randomized, controlled trial of Vitamin D supplementation in patients on peritoneal dialysis to determine the feasibility of a future full-scale RCT exploring if oral administration of vitamin D3 could reduce the risk of subsequent Peritoneal dialysis-related (PD-related) peritonitis.

Aims of the study:

Aim 1: To determine the feasibility of oral vitamin D supplementation among PD patients who have recovered from a recent episode of peritonitis.

Aim 2: To examine the effect of vitamin D supplementation on the risk for peritonitis among patients on peritoneal dialysis.

Patients will be screened for eligibility one month after the onset of PD-related peritonitis, those who meet the inclusion criteria will be enrolled in this study.

All consenting participants will be randomized into the vitamin D treatment group or the control group, general information and baseline biochemistry data would be collected. Patients in the treatment group will be treated with oral Cholecalciferol (2000IU/day) apart from routine treatment for PD. Those in the control group will receive routine treatment for PD. Both groups will be followed for 12 months. During the observational period, any onset of subsequent peritonitis will be recorded, serum 25(OH)D, biochemical indices will be measured every 3 months. Follow up would take place frequently, any outcome events would be recorded.

Aims and hypotheses:

Aim 1: To determine the feasibility of oral vitamin D supplementation among PD patients who have recovered from a recent episode of peritonitis.

Hypothesis1: A large、full-scale randomized controlled trail on the effects of oral vitamin D on the risk for peritonitis among PD patients is feasible.

Aim 2: To examine the effect of vitamin D supplementation on the risk for peritonitis among patients on peritoneal dialysis.

Hypothesis 2: Oral supplementation of vitamin D will reduce the risk of subsequent peritoneal dialysis.

Inclusion Criteria:

1. Medically stable and receiving peritoneal dialysis (PD) for>1 months
2. Age at least 18 years.
3. Serum 25(OH)D<75nmol/l (30ng/ml)
4. Adequate dialysis on evaluation, weekly Kt/V ≥ 1.5 and no clinical uremic symptoms

Exclusion Criteria:

1. Receive Vitamin D2/D3 or drugs known to alter serum 25-hydroxyvitamin D (25(OH)D) levels during the previous 12 months;
2. History of allergic reaction to Cholecalciferol;
3. Current or past malignant disease, active hepatitis or hepatic failure, acute systemic infection, active autoimmune diseases, severe digestive malabsorption or eating disorder, HIV/AIDS;
4. A high probability (assessed by the recruiting physician) of receiving a kidney transplant or transferring to hemodialysis (HD) or drop-out due to socioeconomic causes within 6 months;
5. Pregnant or breastfeeding;