Bone, calcium, and hydroxyproline metabolism in hyperparathyroidism and after removal of parathyroid adenoma

Several laboratory parameters have been followed before and after surgery in a 69-year-old woman with parathyroid adenoma and severe skeletal involvement. High preoperative levels of immunoreactive parathyroid hormone rapidly decreased postoperatively, accompanied by a similar fall in the peptide-bound hydroxyproline (HP) excretion in the urine. Renal clearance of free HP was high both pre- and postoperatively, probably because of renal damage associated with the disease. The high serum alkaline phosphatase levels increased slightly after the operation. The patient developed severe postoperative hypocalcaemia, and prolonged calcium supplement therapy was necessary. The results imply a clear correlation between the changes in Ca homeostasis and the breakdown rate of bone collagenous matrix. Postoperative hypocalcaemia was mainly due to the rapid change in the rates of bone formation and destruction.