Vitamin D Toxicity / Toxicidade da Vitamina D

Abstract Fortification of food products with vitamin D was central to the eradication of rickets in the early parts of the 20th century in the United States. In the subsequent almost 100 years since, accumulating evidence has linked vitamin D deficiency to a variety of outcomes, and this has paralleled greater public interest and awareness of the health benefits of vitamin D. Supplements containing vitamin D are now widely available in both industrialized and developing countries, and many are in the form of unregulated formulations sold to the public with little guidance for safe administration. Together, this has contributed to a transition whereby a dramatic global increase in cases of vitamin D toxicity has been reported. Clinicians are now faced with the challenge of managing this condition that can present on a spectrum from asymptomatic to acute life-threatening complications. This article considers contemporary data on vitamin D toxicity, and diagnostic and management strategies relevant to clinical practice.

Resumo A suplementação de produtos alimentares com vitamina D foi fundamental para a erradicação do raquitismo no início do século XX nos Estados Unidos. Nos quase 100 anos subsequentes, o acúmulo de evidências vinculou a deficiência de vitamina D a uma variedade de desfechos, e isso tem levantado grande interesse público e conscientização dos benefícios à saúde da vitamina D. Os suplementos que contêm vitamina D estão agora amplamente disponíveis tanto nos países desenvolvidos quanto naqueles em desenvolvimento, e muitos estão na forma de formulações não regulamentadas, vendidas ao público com poucas orientações para uma administração segura. Juntos, isso contribuiu para uma transição na qual um aumento global dramático nos casos de toxicidade da vitamina D tem sido relatado. Médicos agora enfrentam o desafio de tratar essa condição que pode apresentar um espectro de complicações assintomáticas a agudas, com risco de vida. Este artigo considera dados atualizados sobre a toxicidade da vitamina D e estratégias de diagnóstico e manejo relevantes para a prática clínica.

Effective use of vitamin D in mild cognitive impairment in older people

Introduction. With age, there is a growing risk of vitamin D deficiency and cognitive impairment. Maintaining the older people's health is socially relevant to health systems in the light of the population ageing trend. The study was aimed at identifying the relationship of vitamin D levels and symptoms of moderate cognitive impairment in older people. Methods. The authors conducted a cross-sectional screening of vitamin D status and cognitive impairment using the memory impairment screen (MIS) questionnaire, as well as the clinical, placebo-controlled study of vitamin D intake at a dose of 2,000 IU/day for 6 months. Results. The frequency of vitamin D deficiency in older patients with signs of cognitive impairment totaled 90.91 %, which was significantly more frequently compared with the group without cognitive impairment, where vitamin D deficiency was found only in 11.36 % of cases. In the dynamics on the background of the vitamin D intake for 6 months, the concentration in the intervention group amounted to 52.34 ± 2.43 ng/ml vs 14.71 ± 1.54 ng/ ml in the placebo group. The results of the study of cognitive impairment using MIS for the treatment group were 3.63 ± 0.01 points, which was significantly higher compared with the placebo group ­ 1.78 ± 0.22 points. A correlation analysis of vitamin D levels and MIS points showed a strong positive relationship, with a correlation coefficient of 0.92. Conclusion. The study identified a positive relationship of increasing vitamin D levels and reducing the symptoms of mild cognitive impairment in older people. Achieving vitamin D levels of over 40 ng/ ml greatly reduces the symptoms of cognitive impairment identified by the MIS questionnaire, however, the issue of treatment of impaired cognitive functions with vitamin D remains debatable.

Differences in the prevalence of vitamin D deficiency and hip fractures in nursing home residents and independently living elderly

ABSTRACT Objective To compare the prevalence of vitamin D deficiency and fracture history in nursing home residents and community-dwelling elderly subjects and to explore the association of vitamin D levels with various characteristics. Materials and methods Sixty-six nursing home residents and 139 community-dwelling elderly subjects participated. Marital status, medical history, medication including vitamin D supplements, smoking, past fractures were assessed. Weight and height were measured and body mass index calculated. Serum 25-hydroxyvitamin D (25-OHD), PTH, Ca, phosphate, creatinine and eGFR were determined. Results In the nursing home residents 25-OHD was lower (17.8 nmol/l, [9.4-28.6] vs. 36.7 nmol/l, [26.9-50], p < 0.001), PTH was higher (5.6 pmol/l, [3.9-8.9] vs. 4.7 pmol/l [3.6-5.8], P = 0.003) and 25-OHD deficiency was more prevalent (65.2% [53.7-76.7] vs. 22.3% [15.4-29.2], p < 0.001) as was elevated PTH (23% [12.8-33] vs. 5.8% [2-10], p = 0.001). 25-OHD correlated negatively with PTH (institutionalized r = -0.28, p = 0.025 and community-dwelling r = -0.36, p < 0.001). Hip fractures were reported by 8% of the residents and 2% of the independent elderly. The only predictor for hip fracture was elevated PTH (OR = 7.6 (1.5-36.9), p = 0.013). Conclusion The prevalence of vitamin D deficiency and secondary hyperparathyroidism was high in the institutionalized subjects. Hip fracture risk was associated with elevated PTH and not directly with vitamin D levels or the residency status.

Vitamin D and diabetes mellitus: an update 2013 / Vitamin D e diabetes melito: uma atualização 2013

Vitamin D deficiency and diabetes mellitus are two common conditions and they are widely prevalent across all ages, races, geographical regions, and socioeconomic conditions. Epidemiologic studies have shown association of vitamin D deficiency and increased risk of chronic diseases, such as cancer, cardiovascular disease, type 2 diabetes, and autoimmune diseases, such as multiple sclerosis and type 1 diabetes mellitus. The identification of 1,25(OH)2D receptors and 1-α-hydroxilase expression in pancreatic beta cells, in cells of the immune system, and in various others tissues, besides the bone system support the role of vitamin D in the pathogenesis of type 2 diabetes. Observational studies have revealed an association between 25(OH) D deficiency and the prevalence of type 1 diabetes in children and adolescents. This review will focus on the concept of vitamin D deficiency, its prevalence, and its role in the pathogenesis and risk of diabetes mellitus and cardiovascular diseases.

A deficiência de vitamina D e o diabetes melito são enfermidades comuns na população e são altamente prevalentes em todas as raças, idades, regiões geográficas e situação socioeconômica. Estudos epidemiológicos mostram uma associação entre hipovitaminose D com o aumento do risco de doenças crônicas, tais como câncer, doença cardiovascular, diabetes melito do tipo 2 e doenças autoimunes como a esclerose múltipla e o diabetes mellitus do tipo 1. A identificação de receptores da 1,25(OH)2 D e da expressão da 1 α-hidroxilase nas células betapancreáticas, em células do sistema imunológico e em uma variedade de células do organismo além do tecido ósseo, suporta o papel da vitamina D na patogênese do diabetes tipo 2 e do tipo 1. Esta revisão apresenta e discute o conceito de deficiência de vitamina D, sua prevalência e seu papel na patogênese e no risco de desenvolvimento do diabetes melito e doenças cardiovasculares.