A nurse is reviewing the laboratory results for four clients. The nurse should recognize that which of the following clients has a manifestation of primary hyperparathyroidism?

Choice A reason: An increased magnesium level may occur in primary hyperparathyroidism due to altered renal handling and bone metabolism. However, the hallmark manifestation is hypercalcemia, which often coexists with elevated magnesium. This finding supports the diagnosis when correlated with other lab values. Choice B reason: A decreased calcium level is inconsistent with primary hyperparathyroidism. This condition typically causes hypercalcemia due to excessive secretion of parathyroid hormone, which increases calcium resorption from bone and renal reabsorption. Choice C reason: Increased phosphorus levels are not characteristic of primary hyperparathyroidism. PTH promotes renal excretion of phosphate, so phosphorus levels are usually low or normal in this condition. Choice D reason: A decreased parathyroid hormone level would suggest hypoparathyroidism, not hyperparathyroidism. In primary hyperparathyroidism, PTH levels are elevated due to autonomous gland activity.