Drechsler C et al. Potential role of Vitamin D deficiency on Fabry cardiomyopathy. J Inherit Metab Dis. 2013 Oct 19. [Epub ahead of print]
Vitamin D has been implicated in cardiac metabolism, although its exact role is still unclear. As Fabry patients are at risk for vitamin D deficiency due to a combination of sunlight avoidance because of heat intolerance and malabsorptive gastrointestinal disease, Drechsler and al hypothesized that vitamin D deficiency may contribute to the cardiomyopathy seen in these patients. They conducted a cross-sectional study of 111 patients with molecularly confirmed Fabry disease. For each patient, they assessed vitamin D status, the presence and severity of cardiomyopathy (with cardiac MRI and echocardiography), proteinuria (by 24-hour urine collection), as well as clinical symptoms of Fabry disease (anhidrosis, acroparesthesia, pain, nausea and vomiting, diarrhea, and heat and physical stress intolerance). Associations between vitamin D levels and the various adverse clinical outcomes were determined by linear and regression analyses and were adjusted for age, sex, BMI and season. The authors found that vitamin D deficiency was present in 73% of patients. Overt vitamin D deficiency was associated with a six fold higher risk of cardiomyopathy; given vitamin D deficiency, its extent was correlated with the severity of proteinuria and with the prevalence of depression, oedema, cornea verticillata and the need for medical pain therapy.
The high prevalence of vitamin D deficiency found in this study is concerning, given the fact that patients with Fabry disease are at risk for osteopenia/osteoporosis, and may suggest that more systematic screening for vitamin D deficiency and/or nutritional vitamin D supplementation may be useful. With regard to the association between vitamin D deficiency and adverse clinical outcomes including cardiomyopathy, the authors themselves stress that “vitamin D may be merely a marker with low levels reflecting disease severity” and that causality cannot be inferred from the cross-sectional data presented. The fact that vitamin D deficiency appears to be associated with outcomes as diverse as cardiomyopathy and cornea verticillata makes it plausible that patients who are more severely affected are simply at greater risk of vitamin D deficiency through reduced intake/absorption and decreased exposure to sunlight. On the other hand, the existence of evidence that vitamin D may play a role in cardiac homeostasis suggests that the contribution, if any, of vitamin D deficiency to Fabry-related cardiomyopathy merits further study.
Posted by Alina Levtova, MD