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Tatiane Vilaça, Marília Brasílio Rodrigues Camargo, Olguita Ferreira Rocha, and Marise Lazaretti-Castro

Background

Strontium ranelate is used to treat osteoporosis. Calcium (Ca) and strontium (Sr) have common chemical features and are absorbed by the same pathways. Vitamin D has a main role in calcium intestinal absorption. The aim of this study was to investigate whether vitamin D status is a determinant of strontium ranelate absorption.

Methods

Twenty-five patients with vitamin D deficiency (25(OH)D<50 nmol/l) and 25 with vitamin D sufficiency (25(OH)D>75 nmol/l) underwent a 4-h oral Sr overload test. Sr absorption was evaluated as the fraction of absorbed dose and the area under the curve. After the baseline overload test, the deficient patients were treated until reaching sufficient vitamin D levels (25(OH)D>75 nmol/l) and the test was repeated.

Results

Changing vitamin D status from deficient to sufficient resulted in a significant increase in 1,25(OH)2D (24.97±4.64×34.62±9.14 pg/ml, P<0.001) and a reduction in parathyroid hormone (73.87±37.50×58.24±20.13 pg/ml, P=0.006). Nevertheless, no differences were found in the parameters used to evaluate Sr absorption between the vitamin D deficient and sufficient groups. In addition, vitamin D3 replacement in the deficient group did not result in enhanced Sr absorption.

Conclusion

Vitamin D status did not interfere with strontium ranelate absorption. Taking into account the benefits of adequate vitamin D status in osteoporotic patients, we strongly recommend the treatment of vitamin D deficiency. However, the data demonstrate that such treatment does not enhance strontium ranelate absorption in patients with mild deficiency.

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John P Bilezikian, Daniel Bikle, Martin Hewison, Marise Lazaretti-Castro, Anna Maria Formenti, Aakriti Gupta, Mahesh V Madhavan, Nandini Nair, Varta Babalyan, Nicholas Hutchings, Nicola Napoli, Domenico Accili, Neil Binkley, Donald W Landry, and Andrea Giustina

The SARS-CoV-2 virus responsible for the COVID-19 pandemic has generated an explosion of interest both in the mechanisms of infection leading to dissemination and expression of this disease, and in potential risk factors that may have a mechanistic basis for disease propagation or control. Vitamin D has emerged as a factor that may be involved in these two areas. The focus of this article is to apply our current understanding of vitamin D as a facilitator of immunocompetence both with regard to innate and adaptive immunity and to consider how this may relate to COVID-19 disease. There are also intriguing potential links to vitamin D as a factor in the cytokine storm that portends some of the most serious consequences of SARS-CoV-2 infection, such as the acute respiratory distress syndrome. Moreover, cardiac and coagulopathic features of COVID-19 disease deserve attention as they may also be related to vitamin D. Finally, we review the current clinical data associating vitamin D with SARS-CoV-2 infection, a putative clinical link that at this time must still be considered hypothetical.