Reply To: I have secondary hyperparathyroidism from malabsorption of fats due to bariatric DS surgery. I have been taking .o25 activated calcitriol 4 a day for about 13 years. What type of test should my doctors order to check on my D3 levels? What ever test they keep using say I am dangerously low and should take an 8 week course of oral D3 at 50,000 units once a week. Can I use both of these supplements at the same time?