Surgical Approaches to Primary Hyperparathyroidism

HORMONES AND DISORDERS OF MINERAL METABOLISM

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SURGICAL APPROACHES TO PRIMARY HYPERPARATHYROIDISM Monica S. Eigelberger, MD, and Orlo H. Clark, MD

INCIDENCE AND HISTORICAL BACKGROUND The first successful parathyroid operation for a patient with primary hyperparathyroidism was performed in Vienna, Austria in 1925. Hyperparathyroidism initially was diagnosed in patients with osteitis fibrosa cystica; however, by the 1930s, nephrolithiasis and nephrocalcinosis became the most common clinically recognized conditions that led to the diagnosis of primary hyperparathyroidism. By the mid-1960s, most patients with primary hyperparathyroidism were identified when hypercalcemia was documented on a routine biochemical test.13,14, 19, 2o Prevalence studies demonstrate that primary hyperparathyroidism occurs in 0.2% to 0.5% of the population, with approximately 100,000 new cases in the United States each year in a female-to-male ratio of 3:l. Because it is a relatively common disorder, all physicians should be aware of the natural history of the disease, a cost-effective method of diagnosis, the indications for surgical therapy, the appropriate use of preoperative localization studies, the surgical approaches, and the long-term benefits versus the risks of surgery. Surgical therapy for hyperparathyroidism began in 1925 when This work was supported by a National Institutes of Health T32 training grant in surgical oncology, and the Edwin H. Zeller Fund and Mt. Zion Health Systems at the University of California, San Francisco/ Mt. Zion Medical Center, San Francisco, California.

From the Department of Surgery, University of California San Francisco Medical Center at Mount Zion, San Francisco, California

ENDOCRINOLOGY AND METABOLISM CLINICS OF NORTH AMERICA

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VOLUME 29 NUMBER 3 SEPTEMBER 2000

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480

EIGELBERGER & CLARK

Mandl, a Viennese surgeon, performed the first successful parathyroidectomy for a patient with hypercalcemia and osteitis fibrosa cystica.2O His patient had previously undergone an unsuccessful parathyroid transplantation. At neck reexploration, a large parathyroid adenoma was found and removed, and the patient made a dramatic recovery. In America, the first patient undergoing neck exploration for primary hyperparathyroidism had one normal parathyroid gland removed. The patient’s clinical condition persisted, and he subsequently underwent six more explorations, the last in 1932, when an adenoma was identified and removed from the mediastinum. The patient died 6 weeks later of tetany and complications of chronic renal failure. In 1932, Albright noted that 80% of patients diagnosed and treated for primary hyperparathyroidism based on the finding of osteitis fibrosa cystica had either nephrolithiasis or nephrocalcin~sis.~~~ 2o These manifestations are still found in approximately 25% of patients with primary hyperparathyroidism. Hyperparathyroidism is now the most common cause of hypercalcemia in outpatients, and second in frequency to cancer in the inpatient populat i ~ nTogether, .~~ hyperparathyroidism and cancer account for 90% of all cases of hypercalcemia. Although most patients with primary hyperparathyroidism have solitary parathyroid adenomas, in the 1950s Copez0 recognized that primary hyperparathyroidism could result from primary chief cell hyperplasia, which warranted more extensive surgical treatment. ETIOLOGY

Primary hyperparathyroidism is caused by the overproduction of parathyroid hormone (PTH) by one or more parathyroid glands that usually results in hypercalcemia. The normal negative feedback loop is altered, and, despite high levels of serum calcium, the gland continues to secret excessive amounts of PTH. The reason for the development of sporadic hyperparathyroidism is unknown. Most (80% to 85%) patients with primary hyperparathyroidism have solitary parathyroid adenomas; others may have diffuse (four-gland) hyperplasia (12% to 15%), and, rarely, double or triple adenomas (2%)or carcinoma (