Dehydration: Causes

Pathogenesis (development of disease)

Isotonic dehydration

Isotonic dehydration results from a lack of isotonic extracellular fluid (fluid outside the cells), which is lost, for example, through vomiting and/or diarrhea (diarrhea). In this case, the body loses water and sodium in equal amounts. Hypotonic dehydration

In this form of dehydration, there is a decrease in extracellular (outside the cell) volume. As a result, antidiuretic hormone (ADH) is released, causing renal water retention (retention of water). Hyponatremia (decreased sodium level) results in an increase in intracellular (located within the cell) volume (fluid influx into the cells). The result is cerebral (affecting the brain) symptoms. There is a risk for cerebral edema (swelling of the brain). Hypertonic dehydration

There is an intracellular water deficiency (intracellular dehydration) with minor hypovolemic symptoms (thirst, tachycardia (heartbeat too fast: > 100 beats per minute), tendency to collapse). Cells in particular lose water, causing erythrocytes (red blood cells) to become smaller. Brain cells also dehydrate. Cerebral symptoms occur. However, the circulation remains stable for a relatively long time due to the transfer of fluid into the extracellular space.The hematocrit (volume fraction of cellular elements in the blood) increases relatively little.

Etiology (Causes)

Behavioral causes

  • Diet
    • Insufficient fluid intake
    • Inadequate and insufficient replacement of lost fluids due to sports, sauna, high ambient temperatures, illnesses such as vomiting and diarrhea (diarrhea), fever

Isotonic and hypotonic dehydration

Renal (kidney-related) sodium losses.

  • Primary renal losses
    • Polyuric phase of acute and chronic renal failure (recovery of renal function; due to massive excretion of up to 10 l of urine per day, water and electrolyte balance is subject to severe fluctuations)
    • “Salt-losing-nephritis” (salt-losing kidney) – ability of sodium reabsorption is lost to the kidney; large amounts of sodium are excreted in the urine even on a salt-free diet
  • Secondary renal losses

Extrarenal sodium losses

  • Enteral (affecting the intestinal tract/intestinal tract) losses due to severe vomiting, diarrhea (diarrhea), fistulas.
  • Losses to other fluid spaces in the setting of pancreatitis (inflammation of the pancreas), peritonitis (inflammation of the peritoneum (abdominal lining)), or ileus (intestinal obstruction)
  • Losses through the skin, e.g., burns.

Hypertonic dehydration

  • Lack of fluid intake
    • During/after physical exertion or high ambient temperatures.
    • Decreased thirst sensation in old age
    • Disease-related (in dysphagia (dysphagia), stomatitis (inflammation of the oral mucosa), esophagitis (inflammation of the esophagus), esophageal stenosis (narrowing of the esophagus)).
    • In case of nursing or consciousness disorders
  • Iatrogenic (caused by medical action): excessive intake of osmotically active fluids.

Renal (kidney-related) water losses.

  • Acute renal failure (polyuric phase: recovery of renal function; due to a massive excretion of up to 10 l of urine per day, the water and electrolyte balance is subject to severe fluctuations. This phase is associated with increased mortality).
  • Diabetic coma, diabetes insipidus
  • Nephropathies (kidney damage) with impaired ability to concentrate.

Extrarenal water losses

  • Diarrhea (diarrhea)
  • Drainage
  • Fever
  • Fistulae
  • Ileus (intestinal obstruction)
  • Hyperventilation (accelerated breathing).
  • Pancreatitis (inflammation of the pancreas)
  • Probes
  • Severe blood loss, sepsis (blood poisoning), burns.
  • Severe vomiting
  • Heavy sweating (sports, sauna, high ambient temperatures).
  • Stomata (eg.B. artificial anus)