[Secondary osteoporosis or secondary contributors to bone loss in fracture. Osteoporosis associated with chronic hyponatremia].

It has been reported that the cognitive dysfunction and the gait instability associated with chronic hyponatremia causes falls, resulting the higher frequency of bone fracture. We demonstrated that hyponatremia is associated with significantly increased odds of osteoporosis using cross-sectional human data and that hyponatremia markedly reduced bone mass via increased bone resorption using a rat model of SIADH. In addition, we showed the sustained low extracellular sodium ion concentrations ( [Na (+) ] ) directly stimulate osteoclastogenesis and that hyponatremia-induced oxidative stress is involved in the mechanism.