Vitamin D is essential for the maintenance of good health. Its sources can be skin production and diet intake. Most humans depend on sunlight exposure (UVB 290-315 nm) to satisfy their requirements for vitamin D. Solar ultraviolet B photons are absorbed by the skin, leading to transformation of 7-dehydrocholesterol into vitamin D3 (cholecalciferol). Season, latitude, time of day, skin pigmentation, aging, sunscreen use, all influence the cutaneous production of vitamin D3. Vitamin D deficiency not only causes rickets among children but also precipitates and exacerbates osteoporosis among adults and causes the painful bone disease osteomalacia. Vitamin D deficiency has been associated with increased risk for other morbidities such as cardiovascular disease, type 1 and type 2 diabetes mellitus and cancer, especially of the colon and prostate. The prevalence of hypovitaminosis D is considerable even in low latitudes and should be taken into account in the evaluation of postmenopausal and male osteoporosis. Although severe vitamin D deficiency leading to rickets or osteomalacia is rare in Brazil, there is accumulating evidence of the frequent occurrence of subclinical vitamin D deficiency, especially in elderly people. RESUMO Deficiência de Vitamina D: Uma Perspectiva Global.A vitamina D é essencial para a manutenção da saúde. A sua fonte principal é a pele ou pode ser ingerida com a dieta. A maioria dos seres humanos depende da exposição solar para adquirir quantidades suficientes de vitamina D. A radiação ultravioleta tipo B transforma o 7-dehidrocolesterol em vitamina D3 (colecalciferol). A época do ano, latitude, pigmentação da pele, idade e uso de filtros solares são fatores que influenciam a produção cutânea. Deficiência de vitamina D pode causar raquitismo e osteomalacia, exacerbar a perda óssea na osteoporose, como também pode associar-se a várias morbidades como doenças cardiovasculares, diabetes mellitus tipo 1 e 2, câncer de prós-tata e de intestino grosso. A prevalência de hipovitaminose D tem sido relatada com grande freqüência mesmo em regiões de baixa latitude e deve ser considerada na avaliação da osteoporose. Embora a deficiência severa levando a osteomalacia possa ser vista raramente no Brasil, evidências se acumulam da freqüente ocorrência de deficiência subclínica, especialmente em idosos.
Primary hyperparathyroidism often presents as an asymptomatic disorder. In our institution, routine serum calcium measurements have now been used as part of medical examination for 23 years. Out of 124 patients consecutively seen at our institution, 47% presented with no symptoms related to the disease, while 25% presented with severe skeletal involvement and osteitis fibrosa cystica, 25% with renal stone disease without overt bone involvement, and 2% with the typical neuropsychiatric syndrome. This same pattern is seen in the city of São Paulo. In severe disease pathological fractures are frequently seen, especially in long bones of the lower extremities, and also loss of lamina dura of the teeth and salt-and-pepper appearance of the skull. Bone mineral density is extremely low in these patients but usually show remarkable recovery following surgical cure. Serum PTH and bone markers are considerable higher in severely affected patients, who also have a high rate of vitamin D deficiency, and the parathyroid lesion is easier located compared with asymptomatic patients. From pathological specimens 87% had histological confirmation of a single adenoma, 6.4% multiple gland hyperplasia and 3.8% carcinoma. Na maioria dos relatos da literatura recente, o hiperparatiroidismo primário apresenta-se, com freqüência, na forma assintomática. Em nossa instituição utilizamos a determinação rotineira do cálcio sérico há 23 anos. Em nossa série de 124 casos consecutivos, 45% não apresentavam sintomas relacionados com a doença, 25% tinham envolvimento esquelético intenso com osteíte fibrosa cística, 25% tinham nefrolitíase sem envolvimento ósseo severo, e 2% apresentavam a síndrome neuro-psiquiátrica típica. Esse mesmo padrão tem sido observado na cidade de São Paulo. Na doença severa são freqüentes as fraturas patológicas, especialmente nos ossos longos dos membros inferiores, como também a reabsorção da lâmi-na dura dos dentes e o aspecto em "sal e pimenta" nas radiografias do crânio. A densidade mineral óssea mostra-se extremamente reduzida nesses pacientes, mas em geral exibe melhora marcante após a cura cirúrgi-ca. O PTH no soro e os marcadores bioquímicos da remodelação óssea estão significativamente mais altos nos pacientes com doença severa, os quais freqüentemente apresentam deficiência de vitamina D e localização mais fácil da lesão paratiroideana, quando comparados aos pacientes assintomáticos. Ao exame anátomo-patológico, 87% tiveram confirmação de adenoma único, 6,4% hiperplasia glandular difusa e 3,8% carcinoma.
Paget's disease of bone is a focal disorder of bone remodeling accompanied initially by an increase in bone resorption, followed by a disorganized and excessive formation of bone, leading to pain, fractures and deformities. It exhibits a marked geographical variation in its prevalence. In Brazil it predominantly affects persons of European descent. The majority of the reported cases of the disease in Brazil are from Recife, owing to its peculiar mixed European colonization over approximately four centuries. The etiology is complex and involves both genetic and environmental factors. The disease is often asymptomatic and diagnosis is usually based on biochemical markers of bone turnover, radionuclide bone scan and radiological examination. Bisphosphonates, in particular zoledronic acid, are regarded as the treatment of choice for Paget's disease of bone.
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