Final answer:
An effective action that a patient with hyperparathyroidism can take to reduce the incidence of renal calculi is to drink large amounts of water and fluids.
Step-by-step explanation:
An effective action that a patient with hyperparathyroidism can take to reduce the incidence of renal calculi is to drink large amounts of water and fluids. This helps to flush away materials that might form kidney stones and keeps the body hydrated, which is important for preventing stone formation.