Background: We designed a comprehensive study to explore different aspectsof primary hyperparathyroidism in a series of Iranian patients. Our study aimed to elucidate the demographic,pathologic, biochemical, and surgical findings of these patients. Material/Methods: In a retrospectivestudy from 1981 to 2003, we reviewed records of 177 patients operated on with the diagnosis of primaryhyperparathyroidism in Shariati Hospital. Patients with secondary or tertiary hyperparathyroidism andthose being re-operated were excluded. Results: 88.1% of the lesions were adenoma, 9.6% hyperplasia,and 1 case proved to be carcinoma. In 1.7% of patients, no pathologic gland(s) were found. The majorityof patients were female (female-to-male ratio: 5.5) and their mean age was 41.9 +/- 13.6 years. Mostof the patients (77.6%) had mild hypercalcemia, and the mean calcium level was 11.2+/-0.8 mg/dl priorto surgery. Patients with hyperplasia had lower calcium levels than patients with adenoma 24 hours post-operation,with mean calcium levels of 8.1+/-1.2 mg/dl versus 9.03+/-1.2 mg/dl, respectively (p=0.02). Mean weightof adenomas was 4.1 gram (range 0.8-25 g). Adenomas were mostly (74%) located in lower parathyroid glandsand 6.3% of them were ectopic. Conclusions: Primary hyperparathyroidism should be expected at youngerages in Iran. Parathyroid hyperplasia in a patient should alert the surgeon of the higher risk of postoperativehypocalcemia.

Keywords: Adenoma - pathology, Adolescent, Calcium - blood, Carcinoma - pathology, Hyperparathyroidism, Primary - pathology, Hyperplasia, Iran, Parathyroid Neoplasms - pathology