Influence of Serum Sodium Levels on Bone Metabolism and Turnover in Hospitalized Patients

Inclusion Criteria: * Adult hospitalized patients with non-hypertonic hyponatremia: serum sodium \< 130 mmol/l, serum osmolality \< 300 milliosmol /kg * age 18 to 99-year-old * Informed consent as documented by signature Exclusion Criteria: * Severe symptomatic hyponatremia in need of intensive care treatment * Hypertonic hyponatremia with serum osmolality \> 300 mOsm/kg * End of life care (palliative treatment) * End stage kidney disease (dialysis) * Acute liver failure * Wernicke encephalopathy * Hepatic encephalopathy during last 2 months * Hepato-renal syndrome * Any bone disease requiring treatment in the last three years * History of fragility fractures * Pre-menopausal women * Hypogonadism (diagnosed before hospitalization) * Hyperthyroidism * Steroid therapy