A strict vegetarian is not getting sufficient vitamin D in his diet, and he develops osteomalacia. This disease is characterized by which of the following changes in his bones?
The hallmark of osteomalacia is widened osteoid seams. Although the trabeculae are normal in number and size, they do not mineralize effectively, and the rim of uncalcified osteoid is much larger than normal. Osteoclast activity is normal in osteomalacia. Increased osteoclast activity is typical of hyperparathyroidism and Paget's disease of bone. There are increased numbers of osteoblasts in osteomalacia, which lay down increased quantities of osteoid in an effo to strengthen the bone. Unfounately, the increased osteoid is not mineralized and the bone remains soft and weak. The bone marrow space is normal in osteomalacia. Marrow fibrosis is more typical of hematopoietic disorders, although hyperparathyroidism may also lead to bone marrow fibrosis. Ref: Molina P.E. (2013). Chapter 5. Parathyroid Gland and Ca2+ and PO4-Regulation. In P.E. Molina (Ed), Endocrine Physiology, 4e.
Decreased osteoblasts
Increased osteoclast activity
Increased osteoid
Marrow fibrosis