Vitamin d was 15.6 ng/ml and normal calcium high in pth and alkaline phosphatase serum level?

Replace vitamin d. Vitamin d deficiency is very common. You need vitamin d to absorb calcium from the intestines. When you don't have enough vitamin d, in order to keep your blood calcium levels normal, your make more PTH to pull calcium from the bones and that raises the alkaline phosphatase. Replacing vitamin d should normalize all the tests.