Final answer:
The nadir of calcium levels after parathyroid resection occurs when there is enough calcium to bind with the receptors on the surface of the cells of the parathyroid glands.
Step-by-step explanation:
The nadir of calcium levels after parathyroid resection occurs when there is enough calcium to bind with the receptors on the surface of the cells of the parathyroid glands. This usually happens when all the processes that regulate blood calcium levels return to normal.