Final answer:
The correct action for the nurse is to administer the prescribed dose of oral phosphate to the client with hyperparathyroidism and a serum calcium level of 12.5 mg/dL, as it may help reduce calcium levels by promoting calcium phosphate formation for renal excretion.
Step-by-step explanation:
The client who has hyperparathyroidism and a high serum calcium level of 12.5 mg/dL should be handled with caution when administering phosphate. Serum calcium levels are influenced by parathyroid hormone (PTH), which regulates calcium by increasing bone resorption, renal calcium reabsorption, and enhancing activation of vitamin D to its active form, calcitriol. In the context of hyperparathyroidism, these mechanisms are overactive, often resulting in elevated calcium levels and reduced phosphate levels due to increased excretion.
Oral phosphate administration is typically used to treat high calcium levels by binding the excess calcium. However, given that the client's calcium level is 12.5 mg/dL, which is on the higher end of normal and does not indicate severe hypercalcemia, administering oral phosphate may be appropriate. The phosphate could help to bring down the elevated calcium levels by facilitating the formation of calcium phosphate, which is excreted via the kidneys, thus potentially normalizing the serum calcium concentration. Therefore, the correct action for the nurse would be D. Administer the dose of oral phosphate, as per the healthcare provider's prescription, provided there are no contra-indications to phosphate administration in this particular client.