P114 Effect of vitamin D on parathyroid hormone, serum calcium and bone mineral density in patients with primary hyperparathyroidism being managed conservatively

Abstract

Abstract Background/Aims Vitamin D deficiency is associated with more severe presentation of primary hyperparathyroidism (PTHP) with high parathyroid hormone (PTH) levels and reduced bone mineral density (BMD). We analyzed data to determine if vitamin D levels had any impact on PTH, serum calcium and BMD at diagnosis and 3 years, in patients being managed conservatively. Methods Retrospective analysis of patients presenting with PHPT. Based on vitamin D level at diagnosis, patients were divided into two groups; vitamin D sufficient (≥ 50 nmol/L) and vitamin D insufficient (≤ 50 nmol/L). The two groups were compared for age, serum calcium and PTH levels at diagnosis and after mean follow up of 3 years. BMD at forearm and neck of femur (NOF) was only analyzed in the two groups at diagnosis, due to lack of 3 year’s data. Results There were a total of 93 patients, 17 males, mean age 70; range 38-90. Mean vitamin D level was 73.39 nmol/L in sufficient group (n = 42) and 34.48 nmol/L in insufficient group (n = 40), (difference between means -38.91, 95% confidence interval -45.49 to -32.33, p < 0.0001). There was no significant difference in age, serum calcium and PTH at the time of diagnosis. After three years, there was no significant difference in vitamin D levels between the two groups (mean vitamin D 72.17 nmol/L in sufficient group and 61.48 nmol/L in insufficient group). Despite rise in vitamin D level in insufficient group, no significant change was observed in this group in PTH and serum calcium levels. BMD was lower at both sites in vitamin D sufficient group and difference was statistically significant at NOF. Data were analyzed using unpaired t test and presented as mean ± SEM. Conclusion 50% of patients presenting with PHPT were vitamin D insufficient at diagnosis. Vitamin D was adequately replaced so that at 3 years there was no significant difference in vitamin D status in the two groups. Serum calcium and PTH were no different in the two groups at diagnosis and at three years, despite rise in vitamin D levels in the insufficient group. Interestingly, BMD was lower at forearm and neck of femur in those with sufficient vitamin D levels and the difference was statistically significant at neck of femur. Our data show that vitamin D insufficiency does not have any significant impact on PTH and calcium levels and that vitamin D replacement is safe in PHPT and does not impact serum calcium and PTH levels in the short term. Lower BMD in those with adequate vitamin D levels is difficult to explain and needs further research. Disclosure M. Khalid: None. V. Deshani: None. K. Jadoon: None.