Dehydration is a common issue especially in the elderly. It ultimately is the loss of water (solely) leading to an increased osmolality and hypernatraemia.
It is a total body water deficit. The difference between dehydration and volume depletion is that volume depletion results in a reduction of extracellular fluid volume when salt and fluid losses > intake. Blood volume is reduced in volume depletion as opposed to intracellular water in dehydration.
😷 Presentation
- Thirst - this is obvious but is the most sensitive indicator.
- Dry mucous membranes - is the second most sensitive indicator.
Other presentations include:
- Loss of skin turgor - however, age is a confounding factor so it is not always reliable.
- Sunken eyes
- Tachycardia, hypotension, delirium/confusion, coma and seizures - these are severe, very late signs.
⚠️ Risk factors and causes
- Poor hydration
- Excessive fluid loss - vomiting, diarrhoea, sweating, diuretics.
- Third spacing
🔍 Investigations
- Hypernatraemia ⬆️
- Serum osmolality ⬆️ . Normal osmolality is 275-295mmol/kg.
- Hyperalbuminaemia ⬆️
- Raised urea ⬆️
🧰 Management
As the aim is simply to replace fluids and not electrolytes, we should encourage oral fluids/enteral fluids. If this is not tolerated, routine maintenance IV fluids should be given. This is commonly given as 5% glucose solution.
If there is any underlying cause, that should also be treated.
