Dehydration: Causes, Symptoms, Treatment, and Prevention

What is Dehydration?

Dehydration occurs when there is a lack of water in the body. This deficiency can arise from insufficient water intake, excessive water loss, or a combination of both. Factors contributing to excessive water loss include profuse sweating, diarrhea, vomiting, burns, intake of diuretics or laxatives, high-protein diets, and excessive salt consumption.

Dehydration becomes a significant health concern when the water loss exceeds 5-6% of body weight. Under normal conditions, water losses are less than 1 ml/min. However, with physical activity or increased external temperature, these losses can escalate to 15-25 ml/min, primarily due to sweating.

Water in the human body is distributed across three compartments:

  1. Intracellular: Constituting 40-50% of body weight, this water is crucial for normal cellular metabolic processes.
  2. Intravascular: Making up 7% of body weight, this water is a key component of blood plasma.
  3. Extracellular: Accounting for 17-20% of body weight, this water is found between cells, facilitating the exchange of substances between capillary blood and cells.

Understanding Types of Dehydration

Dehydration can be categorized into three types:

Hypertonic dehydration is characterized by increased plasma sodium levels and hyperosmolarity. This type of dehydration typically results from profuse sweating and a consequent drop in plasma volume.

Isotonic dehydration usually occurs following vomiting or diarrhea, which leads to the loss of water and electrolytes, particularly sodium, in balanced proportions.

Hypotonic dehydration is characterized by a drop in plasma sodium levels and a reduction in osmolarity. It's often a result of diuretic misuse or rehydration with low-sodium water.

Causes of Dehydration

Dehydration can occur due to excessive loss of water and fluids caused by profuse sweating, fever, diarrhea, and vomiting, or due to insufficient intake of water. Often, these two situations occur simultaneously, where significant water loss is not compensated by adequate fluid intake.

It's worth noting that administering fluids orally, although seemingly the most straightforward solution, may not always be feasible, especially in cases where a person is vomiting and unable to retain any ingested liquid.

The most common cause of severe dehydration is acute gastroenteritis, a violent inflammation of the stomach and intestine's inner walls, primarily caused by viral infections. Other potential causes include bacterial gastroenteritis, Type I diabetes, cystic fibrosis, and malabsorption syndromes.

Who Is at Risk?

Certain groups are more vulnerable to dehydration than others. These include:

  • Children: Due to their higher water content and faster water turnover, children are particularly susceptible to dehydration.
  • Older Adults: As we age, our sense of thirst diminishes. Additionally, older adults may intentionally reduce their fluid intake due to fear of urinary incontinence or due to certain misconceptions.
  • Athletes: During physical activity, the body produces more sweat, increasing the risk of dehydration. It is estimated that for every calorie expended during physical activity, an individual requires 1 ml of water.

Symptoms of Dehydration

Dehydration can manifest through various symptoms, which may differ depending on the individual and the severity of the condition. Some common symptoms include:

  • Thirst (although it's not always present, especially in older adults, and may not correspond to the severity of dehydration)
  • Muscle cramps
  • General weakness
  • Weight loss
  • Reduced urine output, often dark in color
  • Dry lips, skin, and mucous membranes
  • Elevated body temperature
  • Sunken eyes
  • Increased heart rate
  • Impaired mental function
  • Absence of tears when crying
  • Cold extremities

Diagnosing Dehydration

Diagnosing dehydration involves evaluating symptoms and signs through physical examination and medical history. The objective examination is crucial for determining the degree of dehydration. During the physical examination, the doctor measures the capillary refill time, a diagnostic test that assesses systemic perfusion. A prolonged capillary refill time indicates a dehydrated state.

The clinical dehydration scale is a useful tool for estimating dehydration. This scale considers the typical symptoms of dehydration and assigns an increasing score based on their severity. If the overall result of the scores assigned to the symptoms exceeds 5, the patient is likely experiencing moderate or severe dehydration.

Treating Dehydration

Consuming hypotonic drinks can decrease plasma osmolarity and reduce the sensation of thirst before water levels are restored. On the other hand, hypertonic drinks can draw liquids into the intestinal lumen due to osmosis, potentially exacerbating dehydration and causing intestinal disorders.

Following the estimation of the severity of dehydration, the next step is to calculate the amount of fluids to administer. In cases of mild and moderate dehydration, oral hydration therapy is the preferred method. This involves administering special hyposmolar drinks, such as rehydrating sports drinks for children over the age of two.

It is important to avoid carbonated drinks and fruit juices, as these hyperosmolar solutions can exacerbate diarrhea and dehydration. Plain water, while important, does not typically contain enough mineral salts and can lead to electrolyte imbalances.

In cases of severe dehydration or persistent vomiting, intravenous therapy may be employed. Normal feeding should be resumed as soon as the patient can tolerate it.

Preventing Dehydration

Here are some practical tips to prevent dehydration:

  • Take note of your daily water consumption and ensure it meets the recommended intake.
  • Be mindful of factors that influence the absorption of fluids, such as the carbohydrate content of your drinks and the presence of electrolytes like sodium and potassium.
  • Limit exposure to the sun and avoid using saunas or hot tubs when at risk of dehydration.
  • Allow your body time to acclimatize when moving to a hotter climate or during the onset of summer.
  • Avoid using plastic sweat suits for weight loss as they can lead to dehydration.
  • Be aware that high altitudes and long flights can also increase your risk of dehydration.

In conclusion, dehydration is a significant health concern that can have serious consequences if not addressed promptly. By understanding the risks, recognizing the symptoms, and taking proactive measures, it's possible to prevent dehydration and maintain optimal health.

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