Dehydration and hyperhydration - classification, etiology, pathogenesis, and clinical manifestations.
Dehydration (hypohydration) is a condition resulting from loss of body water, often along with electrolytes.
Classification
- 1 Based on serum sodium concentration
Etiology
Isotonic dehydration
- Vomiting, diarrhea.
- Hemorrhage.
- Burns.
- Excessive sweating without electrolyte replacement.
Hypertonic dehydration
- Inadequate water intake (elderly, infants).
- Diabetes insipidus.
- Excessive sweating without water replacement.
- Osmotic diuresis (e.g., hyperglycemia ).
Hypotonic dehydration
- Diuretics (especially thiazides).
- Mineralocorticoid deficiency (Addison’s disease).
- Severe vomiting/ diarrhea with hypotonic fluid replacement.
Pathogenesis
- Reduced extracellular fluid (ECF) volume → decreased tissue perfusion → hypovolemia → hypotension, shock (if severe).
- Cellular dehydration (in hypertonic type) → water shifts from intracellular to extracellular space → brain cell shrinkage.
Clinical manifestations
- Thirst (especially hypertonic).
- Dry mucous membranes.
- Decreased skin turgor.
- Sunken eyes, sunken fontanelle (infants).
- Hypotension, tachycardia (signs of volume depletion).
- Oliguria.
- Confusion, lethargy (in severe dehydration).
- Hypernatremia signs (neurological) if hypertonic type.
Hyperhydration
Definition
Hyperhydration (overhydration) refers to excess body water, which may or may not be associated with sodium gain.
Classification
- 1 Based on sodium content