<prompt> Serum marker of rickets isAcid phosphatesAlkaline phosphataseDecreased serum calciumUrinary posphates  <response>: Amongst the given options, alkaline phosphatase is best because it is raised in all type of rickets.The primary Basic investigations in a child of rickets are :-Serum calciumSerum phosphorusAlkaline phosphataseIf the patient does not respond to calcium and Vit D therapy, secondary investigations are done:-Vit D levelSerum PTHUrinary calcium and phosphorus. 