[Hyponatremia in older persons (part I)-keep diagnosis simple : How to detect tricks and avoid pitfalls].

Old age is a strong independent risk factor for hyponatremia. Dizziness, fatigue, reduced vigilance, cognitive impairment, gait deficits, nausea, vomiting, headache, falls, osteoporosis and fractures, coma and seizures are more frequent and severe than in middle-aged patients. Hyponatremia is mainly caused by the syndrome of inappropriate antidiuretic hormone (SIADH) secretion and also including drugs. Hyponatremia is multifactorial in a significant proportion of older patients. Hyponatremia requires a staged diagnostic approach to identify the underlying cause. The aim of this continuing medical education (CME) report (part I) is to emphasize the special challenges in the diagnostics of hyponatremia, which occur in older patients. Diagnostics should be kept simple. A special algorithm is presented. Part II concerning treatment will follow.