RESUMEN
BACKGROUND: Numerous studies in veterinary species have recently linked vitamin D status with nonskeletal health disorders. Previous studies have indicated that dogs cannot produce endogenous vitamin D via cutaneous production and rely solely on dietary intake of vitamin D. The seasonal variation of vitamin D seen in humans due to changes in ultraviolet (UV) exposure, therefore, is unlikely to be replicated in these animals. OBJECTIVES: The objective of this study was to investigate the natural variation in 25-hydroxyvitamin-D concentrations in dogs subject to seasonal UV exposure. METHODS: This longitudinal study followed 18 healthy dogs fed a standardized diet over 1 year, with blood samples obtained monthly. Two key vitamin D metabolites, 25-hydroxyvitamin-D2 and 25-hydroxyvitamin-D3 , were assessed by liquid chromatography-tandem mass spectrometry in serum samples. Various other biochemical parameters were also measured. Seasonality was assessed using cosinor statistical analysis. RESULTS: Although the dogs were subject to seasonally varying UV radiation, 25-hydroxyvitamin-D and related biomarkers (including calcium and parathyroid hormone) remained stable over time and did not follow a seasonal pattern. 25-hydroxyvitamin-D was not positively correlated with exposure to UV radiation. Nonetheless, variation in 25-hydroxyvitamin-D concentrations between individual dogs was detected. CONCLUSIONS: Given the standardization of diet, we concluded that the seasonal stability of 25-hydroxyvitamin-D concentration (vitamin D status) was likely a direct result of lack of cutaneous vitamin D production in this species and highlights the importance of dietary intake. The variation in 25-hydroxyvitamin-D concentration between animals warrants further investigation.
Asunto(s)
Calcio/sangre , Hormona Paratiroidea/sangre , Vitamina D/análogos & derivados , 25-Hidroxivitamina D 2/sangre , 25-Hidroxivitamina D 2/efectos de la radiación , Animales , Calcifediol/sangre , Calcifediol/efectos de la radiación , Calcio/efectos de la radiación , Cromatografía Liquida/veterinaria , Perros , Femenino , Estudios Longitudinales , Masculino , Hormona Paratiroidea/efectos de la radiación , Valores de Referencia , Estaciones del Año , Rayos Ultravioleta , Vitamina D/sangre , Vitamina D/efectos de la radiaciónRESUMEN
BACKGROUND: Primary hyperparathyroidism is often diagnosed by high calcium levels in blood. It is well known that calcium levels are dependent on vitamin D and Parathyroid hormone (PTH). Since vitamin D has a seasonal variation the calcium levels might also be influenced by seasonal variation. If a seasonal variation in calcium levels exists, this must be considered in the investigation of suspected hyperparathyroidism. The aim of the present study was to investigate the possible influence and magnitude of the seasonal variation of vitamin D and PTH on calcium levels. METHOD: In the present study the individual seasonal variation of 25-hydroxyvitamin D [25(OH)D], PTH and calcium in 69 healthy volunteers living at latitudes with extremely variable seasonal exposure to sunlight have been investigated. RESULTS: As expected the 25(OH)D levels were significantly higher (42%) in summer compared to winter. PTH levels were significantly lower (7%) in summer than in winter. The mean serum concentration of calcium was 1% higher in August than in February, however not statistically significant. A good agreement between summer and winter calcium values was confirmed by Bland-Altman analysis. CONCLUSION: This study did not show any clinically important influence of seasonal variation of 25(OH)D and PTH on calcium that may influence a clinician's decision to investigate suspected hyperparathyroidism.
Asunto(s)
Calcio/sangre , Hormona Paratiroidea/sangre , Estaciones del Año , Luz Solar , Vitamina D/análogos & derivados , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Hormona Paratiroidea/efectos de la radiación , Vitamina D/sangre , Vitamina D/efectos de la radiaciónRESUMEN
Seasonal variation in circulating 25-hydroxyvitamin D (25OHD) levels related to seasonal and inter-day fluctuation in sunlight ultraviolet irradiation, may lead to misjudgments concerning 25OHD status in individual workers around threshold levels. Here, to examine seasonal and inter-day variations in plasma 25OHD, we conducted a longitudinal study involving indoor daytime workers. Subjects were four male indoor daytime workers aged 32-57 yr working in Kawasaki City, Japan. Blood samples were obtained on six days within two two-week periods in February and October, 2008. Plasma 25OHD, serum intact parathyroid hormone (PTH) and 1α,25-dihydroxyvitamin D [1α,25(OH)(2)D] were measured. Individual monthly mean 25OHD levels were 16-56% higher in October than in February (p=0.03), while individual monthly mean intact PTH levels were 15-41% lower in October (p=0.09). No seasonal change was observed in 1α,25(OH)(2)D (p=0.62). Notably, nearly all measured 25OHD levels in February were lower than the reference value of 20 ng/ml. Our study identified the occurrence of seasonal variation in circulating 25OHD and intact PTH levels, even after accounting for inter-day variability, and hypovitaminosis D in wintertime in indoor daytime male workers in Japan. Due to this variability, single spot measurements of 25OHD may lead to misjudgment of workers' vitamin D status.
Asunto(s)
Hormona Paratiroidea/sangre , Estaciones del Año , Deficiencia de Vitamina D/sangre , Vitamina D/efectos de la radiación , Adulto , Humanos , Japón , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Exposición Profesional , Hormona Paratiroidea/efectos de la radiación , Rayos Ultravioleta/efectos adversos , Vitamina D/sangre , Deficiencia de Vitamina D/etiología , Tolerancia al Trabajo Programado/psicologíaRESUMEN
A total of 132 patients with stage I, II, essential hypertension were examined. Indices for central hemodynamics were determined as were the levels of parathormone, calcitonin, and ionized calcium. Radon baths in eukinetic and hypokinetic types of circulation caused a significant reduction in mean hemodynamic pressure and resulted in improvement of patency of arterioles. In so far as hyperkinetic type of hemodynamics is concerned, there was a significant reduction in cardiac index and an increase in specific peripheral resistance. The level of ionized calcium got increased in all the patients, the same being true of the levels of parathormone and calcitonin in cases of eukinetic and hyperkinetic types of circulation.
Asunto(s)
Baños/métodos , Calcitonina/efectos de la radiación , Colonias de Salud , Hemodinámica/efectos de la radiación , Hipertensión/terapia , Hormona Paratiroidea/efectos de la radiación , Radón/uso terapéutico , Adulto , Calcitonina/sangre , Calcio/sangre , Calcio/efectos de la radiación , Humanos , Hipertensión/sangre , Hipertensión/fisiopatología , Masculino , Persona de Mediana Edad , Hormona Paratiroidea/sangre , Inducción de Remisión , UcraniaRESUMEN
To examine the potential causes of increased levels of calcium in serum with increasing dose of atomic bomb radiation, which was obtained from the previous preliminary analysis, levels of parathyroid hormone (PTH) and calcitonin in serum were examined among 1459 subjects in Hiroshima and Nagasaki. A significant effect of radiation on levels of calcium, PTH and calcitonin in serum was found, even after patients with hyperparathyroidism were excluded. The level of calcium in serum increased with radiation dose; this can be explained partly by the increase in the level of PTH with radiation dose. However, the dose effect on calcium remained even after adjustment for PTH, calcitonin and confounding factors such as renal function, serum albumin level and medication. Parathyroid hormone increased initially by 6.8% per gray, but the dose response leveled off after about 1 Gy. The level of calcitonin increased with radiation dose, probably in part due to feedback mechanisms stimulated by the increase in calcium. However, after adjustment for the level of calcium, the increase in the level of calcitonin with dose was still found. Although the etiological mechanisms of the effect of radiation on serum levels of calcium, PTH and calcitonin are unclear, radiation exposure may affect secretion of PTH and calcitonin and regulation of calcium a long time after atomic bomb exposure.