Calcium Citrate Versus Calcium Carbonate in the Management of Chronic Hypoparathyroidism: A Randomized, Double-Blind, Crossover Clinical Trial

In hypoparathyroidism (HypoPT), calcium supplementation is virtually always required, although the disease is likely to be associated with an increased risk of nephrolithiasis. The use of calcium citrate (Ca-Cit) theoretically could have a positive impact on the nephrolithiasis risk because citrate salts are used to reduce this risk. Our objective was to evaluate the potential therapeutic advantage of Ca-Cit in comparison with calcium carbonate (CaCO3) in HypoPT, on nephrolithiasis risk factors, as well as to their ability to maintain desirable serum calcium levels. We also evaluated these preparations on quality of life (QOL). This randomized, double-blind, crossover trial recruited 24 adults with postsurgical chronic hypoparathyroidism at Campus Bio-Medico University of Rome. Participants were randomized 1:1 to Ca-Cit or CaCO3 for 1 month and then crossed over to the other treatment for another month. The primary outcomes were changes in albumin-adjusted serum calcium and in ion activity product of calcium oxalate levels (AP[CaOx] index). Secondary efficacy outcomes included changes in SF-36 survey score, fatigue score, constipation, and adverse events. No difference in terms of AP(CaOx) index was observed between the two groups. However, Ca-Cit was associated with a significant reduction in the oxalate/creatinine ratio compared with CaCO3 (-2.46 mmol/mol [SD 11.93] versus 7.42 mmol/mol [SD 17.63], p = 0.029). Serum calcium and phosphorus concentration was not different between the two calcium preparations. Ca-Cit was associated with less constipation (p = 0.047). No difference was found in QOL scores. Although Ca-Cit did not modify the AP(CaOx) index when compared with CaCO3, it was associated with a reduction in urinary oxalate excretion that could have a potential beneficial effect on nephrolithiasis risk. These results are likely to have clinical implications in HypoPT, particularly those who do not tolerate CaCO3 and those affected by nephrolithiasis. A longer-term experience is needed to confirm these findings. (c) 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR)

Cardiovascular Autonomic Neuropathy as a New Complication of Postsurgical Chronic Hypoparathyroidism

ABSTRACT   Postsurgical hypoparathyroidism (hypoPT) increases fatigue and seems to affect the risk of mortality. Cardiovascular autonomic neuropathy (CAN) is an impairment of the cardiovascular autonomic system, a cause of increased mortality, and associated with increased fatigability. The aim of this study is to evaluate CAN in hypoPT and its relationship with hypocalcemia, PTH levels, and hyperphosphatemia. This is a cross-sectional study comparing 51 postsurgical hypoPT patients treated with calcium and calcitriol and 43 control subjects without any PTH/calcium/phosphate disorders who underwent thyroidectomy. CAN was assessed by heart rate (HR) response to deep breathing, HR response to the lying-to-standing test, HR response to the Valsalva maneuver, and blood pressure response to standing. Participants were considered to have "early CAN" if they had one abnormal result in the HR tests and "definite CAN" with two or more abnormal results. The prevalence of CAN was 23% in the control group and 78% in the hypoPT group (OR 11.48; 95% CI, 4.48 to 32.17). Patients with hypoPT and serum calcium (sCa) ≥8.5 mg/dL had a prevalence of early CAN of 72.4% and the prevalence was 86.4% in those with sCa <8.5 mg/dL. Definite CAN was found in 2.3% of the control group, 24.1% of the hypoPT group without hypocalcemia, and 59.1% of the hypoPT group with hypocalcemia. In the hypoPT group, the OR for definite CAN in the patients with hypocalcemia compared to the patients with normocalcemia was 4.54 (95% CI, 1.36 to 15.11). The association between low sCa and definite CAN was confirmed after adjustment for confounders with OR 13.62 (95% CI, 2.12 to 149.84). No association was found between definite CAN and PTH levels or high phosphate levels. HypoPT is associated with CAN and hypocalcemia seems to affect its severity. Larger and prospective studies are needed to confirm our findings. © 2018 American Society for Bone and Mineral Research