Endocrine Abstracts

There are limited data on the natural history of normocalcemic PHPT and it is unclear how the patients should be regarded vis a vis parathyroid surgery. Among the 1500 admissions/year for 10 years referred to our outpatient endocrine clinics for a variety of diseases, we collected 481 subjects with high serum levels of PTH. In the presence of hypercalcemia, a diagnosis of primary hyperparathyroidism was performed in 127 (26%). Other 354 (74%) subjects were normocalcemic: 186 (51%) were vitamin D deficient, 94 (27%) had renal failure, 39 (11%) suffered from secondary hyperparathyroidism due to different causes (mainly use of lithium and thiazides); the remaining 37 subjects (11%) (33 females, 4 males, age range 71±11 years) had serum calcium and creatinine in the normal range and had a high PTH level. Among them 10 dropped out and the other 27 were followed up for 1–10 years. Over time 10 out of the 25 hyperparathyroid subjects became hypercalcemic (group A, followed up for 4–10 years, mean 7 years) while the others(17 pt) continue to be normocalcemic (group B, followed up for 1–10 years). The two groups were not different at baseline for calcium, creatinine, BMD expressed as T-score at lumbar spine (LS) and femoral neck (FN) while subjects in group A were significantly older than in group B. In group A (normocalcemic hyperparathyroid group) followed over time, nine patients had a significant reduction of BMD, three had also a fracture (two vertebral and one Colles) and one a kidney stone, none deterioration of renal function. Eight patients were operated on and a parathyroid adenoma was removed. In group B, followed over time, five subjects had a significant reduction of BMD. In conclusion our retrospective longitudinal study suggest that patients with normocalcemic hyperparathyroidism have a more important involvement of bone than not in mild primary hyperparathyroid patients. More studies are needed to identify patients who may develop features of PHPT over time.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.