Aetiology

In majority of cases dehydration is caused by a disease and/or the effects of medication and NOT primarily due to lack of access to water (1).

Causes include:

• fluid loss without water replacement - for example, an unconscious patient with fluid lost from diarrhoea, burns, vomiting, sweat, respiration
• diabetes insipidus
• osmotic diuresis - for example, diabetic coma
• Conn's syndrome - hypokalaemic alkalosis
• Cushing's syndrome
• incorrect intravenous fluid replacement
• some patients with hyperosmolar non-ketoacidotic diabetic coma; this condition may also cause hyponatraemia
• hypothalamic dysfunction

Reference:

• (1) Thomas DR et al. Understanding clinical dehydration and its treatment. J Am Med Dir Assoc. 2008;9(5):292-301.