osteoblasts and secreted into the serum in an unchanged state. Serum con-
centrations of osteocalcin are, therefore, directly related to osteoblastic activ-
ity. It is a more specific marker than alkaline phosphatase, because other
organs, such as the liver and kidney, produce that enzyme.
Radiologic methods such as conventional x-ray can be used to detect
osteoporosis, but only after patients have lost 30–50% of their bone mass.
Dual-beam photon absorptiometry allows a much more accurate diagnosis
of loss of bone mass.
112.The answer is a.(Favus, pp 378–379. Kumar, pp 679–681. Kasper,
pp 656–658.)The patient is suffering from multiple myeloma, which causes
increased plasma cell activity and anemia (hemoglobin data and increasing
fatigue). Those plasma cells produce elevated levels of interleukin 1 (IL-1),
which functions as an osteoclast activation factor, resulting in elevated serum
calcium (12.3 mg/dL). Depletion of bone calcium results in lytic lesions of
the skull and pelvis as well as compression fractures of the spine. The Bence-
Jones protein represents free-immunoglobulin light chains, a diagnostic fea-
ture (Bence-Jones proteinuria) in the urine of patients with multiple
myeloma. RANK is found on osteoclasts, binds to RANK-L produced by
osteoblasts, and stimulates osteoclastic activity (“High-Yield Facts”, p 21).
113.The answer is b.(Favus, pp 330–335. Kumar, pp 453–455. Greenspan,
pp 320–322. Junqueira, pp 135, 148. Kasper, pp 2247–2248.)The patient suf-
fers from osteomalacia, a disease related to malnutrition, specifically vitamin
D deficiency. On the basis of the first bone biopsy in which the tissue was
decalcified, one could make a diagnosis of osteoporosis. The second, non-
decalcified bone biopsy indicates that osteoid is being formed but is not
undergoing mineralization. This correlates with the low 25-hydroxyvitamin
D levels. Vitamin D replacement and calcium supplementation would be
prescribed for this patient.
114.The answer is e.(Favus, pp 398–401. Kasper, pp 2091, 2226–2231,
- Greenspan, pp 310–320. Kumar, pp 1282–1284.)Osteoporosis is a major
problem of normal aging in both sexes but is particularly prevalent in
older women. In that disease, the quality of bone is unchanged, but the
balance between bone deposition and bone resorption is lost. The disease
is prevalent in postmenopausal women because the protective effect of
estrogens is no longer present. Osteoporosis may also be induced by other
Specialized Connective Tissues: Bone and Cartilage Answers 211