Intracellular, extracellular and generalized dehydration

Dehydration is the result of a loss of salt and water isotonic to the plasma, not compensated by intake.

The appearance of dehydration results from the conjunction of two types of phenomena: the first is an excessive loss of renal water linked or not to sodium (renal or extra-renal), the second is the impossibility of compensating for water (and/or sodium) losses due to a lack of normal access to water and salt.

You should know that water is distributed in the body as follows:

• The intracellular compartment contains 2/3 of the water which represents 40% of the body weight

• The extracellular compartment contains 1/3 of the water, distributed as follows:

  • Blood plasma represents 5% of body weight

  • Interstitial fluid represents 15% of body weight

Each compartment contains a particular concentration of ions and electrolytes and if this is unbalanced, water leaks from one compartment to another to rebalance the concentrations and there is therefore dehydration.

There are therefore 3 types of dehydration depending on the compartment that becomes dehydrated: intracellular, extracellular and generalized which is the most severe and chronic form.

What causes the different types of dehydration?

Their causes are essentially the same for the three types of dehydration.

First of all, there are renal losses : among these we can cite excessive diuresis (volume of urine evacuated in 24 hours), which is found for example in the case of diabetes. They can also be caused by different pathologies: mainly renal insufficiency of different types.

Digestive losses are also a common cause of dehydration that must be treated quickly: the most obvious examples are diarrhea and vomiting.

Skin losses are a sneaky cause whose impacts are too often underestimated; they include excessive sweating, fever and heat stroke.

Just like skin losses, pulmonary losses do not necessarily seem very significant to us, but be aware that hyperventilation during sports is one of the causes of intracellular dehydration.

Other external factors can come into play to dehydrate us and excessive alcohol consumption is a very good example.

What are the common clinical signs of dehydration?

To identify dehydration, you must first know the precise circumstances leading to it.

We can then consider a clinical examination during which the different symptoms will be noted: this will allow the diagnosis of the type of dehydration and its severity.

The useful biological tests are as follows: to determine the origin of the disorder, we will assess the losses of water and sodium (vomiting-diarrhea, etc.), we will also determine the diuresis (volume of urine excreted in 24 hours).

What are the common clinical signs of dehydration?

To identify dehydration, you must first know the precise circumstances leading to it.

We can then consider a clinical examination during which the different symptoms will be noted: this will allow the diagnosis of the type of dehydration and its severity.

The useful biological tests are as follows: to determine the origin of the disorder, we will assess the losses of water and sodium (vomiting-diarrhea, etc.), we will also determine the diuresis (volume of urine excreted in 24 hours).

Extracellular dehydration

This type of dehydration results from a loss of water at the extracellular level while the volume of intracellular water remains the same, maintaining an effective extracellular osmotic pressure.

How to detect dehydration?

Here is a list of symptoms that will point you in the direction of extracellular dehydration:

• Fatigue,

• Lack of appetite, no thirst

• The mucous membranes remain moist

• Poor weight loss

• Appearance of peripheral and jugular veins: flat with cold, discolored ends, this is a sign of low central venous pressure.

• Decrease in blood pressure with orthostatic hypotension: the consequence is an acceleration of the pulse to compensate and continue the normal supply of oxygen to the organs.

• Loss of skin tone with clear skin fold: at the level of the abdominal wall, the subclavicular region and the inner side of the thighs (difficult to interpret in the elderly).

• The eyeballs are sunken and hypotonic.

A case of severe extracellular dehydration will be suspected when: very low blood pressure (less than 80 mmHg), cold extremities and the presence of marbling on the skin

The risks of dehydration

Complications of severe extracellular dehydration include: hypovolemic shock with acute tubulopathy or oliguria with renal failure.

Intracellular dehydration

Intracellular dehydration occurs when the intracellular sector becomes dehydrated and therefore contracts on itself: because there is an increase in plasma osmolarity (often too high a sodium concentration) that the body has compensated for by sending water from the intracellular sector into the plasma to dilute the excess sodium.

• Decrease in blood pressure with orthostatic hypotension: the consequence is an acceleration of the pulse to compensate and continue the normal supply of oxygen to the organs.

• Loss of skin tone with clear skin fold: at the level of the abdominal wall, the subclavicular region and the inner side of the thighs (difficult to interpret in the elderly).

• The eyeballs are sunken and hypotonic.

A case of severe extracellular dehydration will be suspected when: very low blood pressure (less than 80 mmHg), cold extremities and the presence of marbling on the skin

The risks

Complications of severe extracellular dehydration include: hypovolemic shock with acute tubulopathy or oliguria with renal failure.

Intracellular dehydration

Intracellular dehydration occurs when the intracellular sector becomes dehydrated and therefore contracts on itself: because there is an increase in plasma osmolarity (often too high a sodium concentration) that the body has compensated for by sending water from the intracellular sector into the plasma to dilute the excess sodium.

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