A summary of the new phenomenon of normocalcemic hyperparathyroidism and appropriate management.

PURPOSE OF REVIEW: The phenomenon of normocalcemic hyperparathyroidism (NCHPT) remains largely unknown and not well understood. Recently, with more investigators reporting on the subject, NCHPT has been proposed to be a precursor of the classic hypercalcemic primary hyperparathyroidism (HPT).

RECENT FINDINGS: This manuscript will discuss the most recent findings regarding the diagnosis, natural history, treatment and follow-up of NCHPT. Approximately 1-4% of patients undergoing parathyroidectomy for HPT are normocalcemic before surgery. To date, observation appears to be a well tolerated approach, as long as these patients remain normocalcemic. When patients with NCHPT are followed for an average of 4 years, 22% will progress to hypercalcemia. In some instances, NCHPT may be treated with parathyroidectomy, but the indications and long-term outcome for this approach are unknown.

SUMMARY: This condition is now being diagnosed more frequently. Patients with vitamin D deficiency, mild renal dysfunction, and urinary calcium leak are often mislabeled as having NCHPT and these conditions should always be excluded and medically treated. There is some evidence that parathyroidectomy may be beneficial when NCHPT patients are properly selected. The authors suggest caution when approaching these patients surgically because multiglandular disease and operative failure may be more common in these rare patients.