This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Medicine
In osteomalacia which of the following biochemical feature is true? 
Select and explain. 
A. Elevated serum calcium level, B. Elevated serum phosphate level, C. Elevated serum alkaline phosphatase, D. Elevated 25-hydroxyvitamin D3
C: Elevated serum alkaline phosphatase
Answer: C: Elevated serum alkaline phosphatase 
Explanation: 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