<s>[INST] sir my calcium blood level is 8.7 and 48 years old. as per doctor advise i have used 0000 iu d3 once in week last four month along with calcitrol but still my level continuing as 8.6 , how long i should take same medicine, and suffering back pain ,knee pain while step up stair [/INST] Hello and welcome to HCM,Vitamin D supplement (calcitriol) has to be taken till blood levels of vitamin D and calcium reach normal range.Back pain and knee pain are most probably associated with deficiency of vitamin D and calcium if there is no other known cause of back and knee pain.Thanks and take careDr Shailja Puri </s>