This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Which of the following biochemical findings are seen in osteoporosis? 
Select and explain. 
A. Low Ca, high P04. high alkaline phosphatase, B. Low Ca. low P04. low alkaline phosphatase, C. Normal Ca, normal PO4, normal alkaline phosphatase, D. Low Ca, low P04, normal alkaline phosphatase
C: Normal Ca, normal PO4, normal alkaline phosphatase
Answer: C: Normal Ca, normal PO4, normal alkaline phosphatase 
Explanation: In osteoporosis the levels of calcium, PO4, alkaline phosphatase and parathyroid hormone are normal. Vitamin D deficiency is commonly associated with this condition. Osteoporosis is a skeletal disorder characterized by a loss of bone osteoid that reduces bone integrity, resulting in an increased risk of fractures. Most common causes are aging, use of steroids, alcoholism, smoking and sex hormone deficiency. According to WHO, osteoporosis is defined as a bone density that falls 2.5 standard detions (SD) below the mean for young healthy adults of the same sex. Ref: Fitzgerald P.A. (2013). Chapter 26. Endocrine Disorders. In M.A. Papadakis, S.J. McPhee, M.W. Rabow, T.G. Berger (Eds), CURRENT Medical Diagnosis & Treatment 2014.