Review Question - QID 5558

In osteopenia, elevated parathyroid hormone (PTH), high alkaline phosphatase as well as low calcium (Ca), phosphorus and vitamin D would be expected.

In the setting of osteopenia/osteoporosis, there is a positive feedback to increase PTH in response to low serum calcium levels. In response, there is a corresponding increase in alkaline phosphatase and decrease in phosphorous and circulating vitamin D levels.

Fraser writes a concise, yet thorough synopsis on primary and secondary hyperparathyroidism. In the article, the summary regarding osteopenia/osteoporosis (typically a state of hypovitamin D) begins by stating an initial state of decreased ionised calcium, which increases PTH, results in 3 primary effects: an attempt to increase gut absorption of Ca, mobilize Ca from the bone via osteoclasts and activate vitamin D at the kidney (1,25-vitamin D).

Figure A exhibits a left femoral neck fracture, which is a fragility fracture associated with poor bone density. Illustration A is a figure from Fraser's article exhibiting the feedback loop from the hypothalamus, pituitary, adrenal/glandular axis.

Incorrect answers:
Answers 1,3: These states represents a potential primary parathyroidism which may caused by an endocrine disorder or tumor.
Answers 4,5: These states represent a mismatch in the hypothalamic, pituitary, adrenal/gland axis, which may be caused by either a primary parathryoid tumor, or a secondary endocrine mismatch disorder.