In osteomalacia, which of the following laboratory findings is expected?

In osteomalacia, the primary issue is the inadequate mineralization of osteoid due to vitamin D deficiency, which leads to the release of parathyroid hormone (PTH) in response to low calcium levels. This regulatory mechanism results in a complex interplay of laboratory findings.

In this condition, both calcium and phosphate levels in serum are typically low due to the impaired ability to absorb these nutrients from the diet and inadequate mineralization of bone. Consequently, the body compensates for low calcium levels by increasing PTH secretion. Elevated PTH helps mobilize calcium from bones and promotes renal reabsorption of calcium; however, it also causes renal wastage of phosphate.

Therefore, in osteomalacia, one would expect to find low serum calcium and phosphate levels, along with high levels of PTH. This combination of low calcium and phosphate, with an elevated response from the parathyroid glands, illustrates the body's attempt to maintain calcium homeostasis despite the underlying mineralization defect.

This clear correlation of laboratory findings highlights the nature and physiological responses seen in osteomalacia, making the identification of low calcium, low phosphate, and high PTH the expected outcome in this condition.