To determine the maintenance dose of vitamin D supplementation required for children with epilepsy to maintain normal vitamin D level.

children aged 2-16 years diagnosed with idiopathic epilepsy will be randomized to receive either cholecalciferol doses (400IU vs 1000IU) with follow up at 3 and 6 months post supplementation.

Inclusion Criteria:

1. Children aged between 2-16 years who were diagnosed with Epilepsy and being treated with AEDs
2. Followed up in the outpatient pediatric neurology clinic at King Khalid University Hospital during the period of two years.

Exclusion Criteria:

1. Children with pre-existing vitamin D metabolism problems; because they are known to need different vitamin D doses and monitoring for clinical improvement:

   • Vitamin D dependent rickets
   • Malabsorption syndromes like celiac disease, inflammatory bowel disease
   • Renal disease
   • Hepatic disease

2. Children who are not safe to start vitamin D supplementation; because vitamin D supplementation will causes toxicity and induces nephrocalcinosis:

   • Hypercalcemia at baseline total corrected calcium >2.5mg/dl
   • Vitamin D level > 250 nmol/L
   • Urine calcium: creatinine ration > 1.2 mol/mol, or > 0.41g/g.