Which of the following biochemical findings are seen in osteoporosis?

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.