What is tertiary hyperparathyroidectomy?

Excessive secretion of PTH after long-standing secondary hyperparathyroid, results in hypercalcemia, after successful renal transplant hyperparathyroid persists, autonomous hypersecretion causing hypercalcemia (hypertrophied glands cannot get back to normal after renal transplant) Dangerous since phosphorus is high, so high phosphorus w/calcium leads to diffuse calcinosis