Study of intact (1-84) parathyroid hormone secretion in patients undergoing parathyroidectomy.

Patterns of intact (1–84) parathyroid hormone (intact PTH) elimination and subsequent recovery of parathyroid function were studied in 12 patients undergoing parathyroidectomy. Nine patients had primary hyperparathyroidism (HPT), with single gland disease in 6 and multiple gland disease in 3. Two patients had subtotal parathyroidectomy for HPT secondary to chronic renal failure and 1 underwent excision of a hyperfunctioning parathyroid autograft. Using a sensitive 2-site immunochemiluminometric assay, serum intact PTH levels were measured preoperatively, intraoperatively, and postoperatively. A dual phase pattern of hormone clearance was found in 10 of the 12 patients, including the patient undergoing autograft excision. A monoexponential clearance pattern was seen in the remaining 2 patients, both of whom had subtotal parathyroidectomies for multiple gland disease. In the patients with primary HPT due to single gland disease, the early phase of intact PTH clearance had a half-life (T1/2) of 3.3 (±standard deviation 0.9) minutes and a late T1/2 of 96.4 (±standard deviation 92.7) minutes. Calculation of decay curves and half-lives for the patients undergoing subtotal parathyroidectomy was more difficult because of the inherent uncertainty in determining time zero. Nevertheless, in all but 2 patients, the clearance pattern was biexponential and the T1/2 measurements were very similar to those encountered in patients with single-gland disease. In the 2 patients with monoexponential clearance, the T1/2 figures were 86.7 minutes and 26.7 minutes, respectively. In the patients undergoing parathyroidectomy for primary HPT, levels of intact PTH were lowest at 1–3 hours after surgery, recovering to normal in the majority of patients by 18–40 hours.