Increase in the serum parathyroid hormone level during a bisphosphonate drug holiday

Incidental Normocalcemic Primary Hyperparathyroidism Presenting With Symptomatic Hypophosphatemia: A Case Report

Normocalcemic primary hyperparathyroidism (NHPT) is a newly defined variant of primary hyperparathyroidism (PHPT). It's defined by consistently normal total and ionised calcium levels with elevated parathyroid hormone in the absence of secondary causes of hyperparathyroidism in at least three consecutive times over a period of three to six months. Consensus whether the same criteria used to recommend surgery in PHPT should be used to recommend surgery in NHPT is still lacking. Even though PHPT is known to cause hypophosphatemia, serum phosphate is not relevant when diagnosing it or NHPT. No current guideline include any phosphate cutoff level to guide management or indicate surgery in PHPT or NHPT patients. Herein, we present a rare case of incidental NHPT presenting with symptomatic hypophosphatemia and managed surgically.

Effect of general anesthesia and intubation on parathyroid levels in normal patients and those with hyperparathyroidism

BACKGROUND

Induction of general anesthesia and endotracheal intubation may precipitate parathyroid hormone (PTH) elevation in patients with primary hyperparathyroidism (HPT). The purposes of this study were to revisit this observation and to study its impact in healthy patients.

METHODS

Patients with primary HPT who underwent parathyroidectomy were retrospectively studied. The PTH was sampled and compared: before, immediately after general anesthesia and endotracheal intubation, and 15 minutes after parathyroidectomy. Healthy adults who underwent elective operations were prospectively studied. The PTH was sampled before general anesthesia and endotracheal intubation, immediately after, and 15 minutes later.

RESULTS

Thirty-one patients, aged 28-89 years (mean 60.1 ± 13 years), were retrospectively studied. The PTH was significantly elevated after general anesthesia and endotracheal intubation (P = .014). Fifty patients, aged 21-86 years (mean 54 ± 15 years), were prospectively studied. The PTH elevation after general anesthesia and endotracheal intubation was not significant.

CONCLUSION

General anesthesia and endotracheal intubation causes an immediate, steep, and significant PTH elevation in patients with primary HPT but only a minor change in healthy adults. The difference may be attributed to an impaired adrenergic response in patients with primary HPT.