In osteomalacia which of the following biochemical feature is true?: (A) Elevated serum calcium level, (B) Elevated serum phosphate level, (C) Elevated serum alkaline phosphatase, (D) Elevated 25-hydroxyvitamin D3
Answer is C. In osteomalacia, serum ALP (alkaline phosphatase) levels are raised, 25(OH)D levels are low or undetectable, PTH is elevated, serum calcium and phosphate levels may also be low but normal values do not exclude the diagnosis. Reference : page 1127 Davidson's Principles and practice of Medicine 22nd edition