Review Question - QID 4397

Decreased calcium, increased serum phosphate, increased alkaline phosphatase, and increased parathyroid hormone are all characteristic of renal osteodystrophy.

Renal osteodystrophy represents a spectrum of disease seen in patients with chronic renal disease. It is characterized by bone mineralization deficiency due to electrolyte and endocrine abnormalities. High turnover renal osteodystrophy is classically associated with significantly increased phosphate and parathyroid hormone (PTH) levels. Chronic renal disease leads to a decrease in renal phosphorus excretion, which leads to phosphate retention and a significant increase in PTH levels. This ultimately can lead to tertiary hyperparathyroidism.

Tejwani et al present a review article on renal osteodystrophy. They state that in high-turnover renal osteodystrophy PTH secretion is increased and, in the absence of medical intervention, leads to parathyroid gland hyperplasia. This hyperplasia is associated with loss of feedback inhibition in normal regulation of PTH secretion; consequently, even after correction of the renal disease, the parathyroid gland continues to secrete excessive levels of PTH.

Illustration A shows a pathologic fracture secondary to renal osteodystrophy.

Incorrect Answers:
2-This series of lab values is consistent with a diagnosis of nutritional rickets due to vitamin D deficiency.
3-This series of lab values is consistent with a diagnosis of low-turnover renal osteodystrophy. This is classically caused by excess deposition of aluminum into bone which impairs PTH release from the parathyroid gland and disrupts the mineralization process.
4-This series of lab values is consistent with a diagnosis of hypoparathroidism.
5-This series of lab values is consisten with a diagnosis of primary hyperparathryoidism.