The impact of vitamin D status and parameters of calcium metabolism in patients with primary hyperparathyroidism

Background: There is ample evidence associating vitamin D deficiency in primary hyperparathyroidism (PHP) patients with more severe disease manifestations and increased risk of postoperative hypocalcemia. Yet, there is limited data regarding the safety of vitamin D repletion in these patients. Aim: To assess the safety of vitamin D repletion in PHP patients in a real-world setting. Design: We included patients with asymptomatic PHP and few symptomatic patients who declined surgery, followed in our clinic, and treated on a routine basis with 2000 IU/day of vitamin D₃. Methods: Serum calcium(sCa), PTH, 25-hydroxyvitamin D, and 24h urinary calcium (uCa) and creatinine collections were compared between the lowest and the highest vitamin D time points. Results: There were 40 patients of a mean age was 63±10 years. 25(OH)D at lowest and highest vitamin D time points was 15.5±6.2 ng/ml and 33.2±8, respectively (P < 0.001). Serum calcium was not affected by the changes in vitamin D levels. In none of the patients did sCa exceed 11.5 mg/dL. uCa was 220±110 mg/24h at the lowest vitamin D time point and 260±140 at the highest vitamin D time point (P=0.14). uCa exceeded 400 mg/24h in two vs. five patients (P=0.23) at the lowest and highest vitamin D time points, respectively. PTH was not significantly different between the different vitamin D time points. Discussion/Conclusion: Vitamin D repletion in PHP seems safe. Considering the documented adverse influence of vitamin D deficiency in PHP, particularly on skeletalmanifestations and on the postoperative course, vitamin D repletion is warranted.