Efficacy of Calcium Citrate Versus Calcium Carbonate for the Management of Chronic Hypoparathyroidism

Hypoparathyroidism is an endocrinopathy characterized by a deficient secretion or action of PTH associated with low calcium level. According to the European guideline (2015), standard treatment includes oral calcium salts and active vitamin D metabolites to relieve symptoms of hypocalcaemia, maintain serum calcium levels in the low normal range and improve the patient's QoL Calcium carbonate is most often used and less expensive than other calcium preparations and contains the highest concentration of elemental calcium per gram (42%). It requires gastric hydrochloric acid to form carbonic acid (H2CO3) that immediately decomposes into water (H2O) and carbon dioxide (CO2). CO2 is responsible for its side effects such as flatulence, constipation and general gastrointestinal disorders. Therefore, in some patients it is better to find an alternative to calcium carbonate. Calcium citrate should be recommended to patients with achlorhydria or on treatment with proton pump inhibitors (PPI) as well as to patients who preferred to take supplements outside mealtimes. furthermore, patients with hypoparathyroidism have an increased risk of kidney stones. Kidney stones are formed by calcium salts, among which the most frequent ones are calcium-oxalate (70-80%), followed by calcium-phosphate and uric acid. Citrate salts are widely used in the treatmentof nephrolithiasis, since have shown an inhibitory effect on kidney stone formation. Up to now, there are no studies aimed to investigate the efficacy of calcium citrate in the management of subjects with chronic hypoparathyroidism. In particular, we will investigate if calcium citrate compared to calcium carbonate does not affect the risk of renal stones, if it is able to maintain normal calcium levels and, if it has an impact on QOL, in subjects with chronic hypoparathyroidism.