Dehydration vs Hyponatremia: What’s The Difference

Updated: Mar 8

A well-known fact about the body is that it is made up of 60% of water. Water plays a huge role in the function of the human body.


According to an article, “The Water in You: Water and the Human Body,” published by Water Science School, the brain and heart are 73% water, the lungs are 83% water, skin is 64% water, the muscles and kidneys are 79% water, and bones are 31% water.


It is recommended for males to consume roughly 3 liters and females 2 liters of water on a daily basis. An additional 3 to 4 liters may need to be consumed to replenish and hydrate your body if you exercise. If your body is not properly hydrated it can lead to dehydration. In rare cases, you can flood your system with too much water and become hyponatremia.



What is Dehydration

When your organs are deprived of fluids and unable to properly function your body is dehydrated. Not only is water imperative for your body to function normally, but so are electrolytes. The body needs a certain amount of water to electrolyte ratio to work adequately.


To upset the balance between water and electrolytes can lead to experiencing symptoms of dehydration. Fluid excretion can tip the scales through sweating, breathing, and urination. The three most common causes of dehydration are sweating, vomiting, and diarrhea. Depending on how the scale dips, there are three types of dehydration.


Types of Dehydration


Isotonic Dehydration

Both water and sodium levels are low. Your body has lost an equal amount of water and electrolytes.


Signs and Symptoms of Isotonic Dehydration

  • Decreased blood pressure

  • Central venous pressure (blood flow to and from the heart)

  • Tachycardia (fast heart rate)

  • Central nervous system ischemia (insufficient blood flow to the brain)

  • Oliguria (reduced urination)

  • Dry mucous membranes (dry nose)

  • Dry skin

  • Reduced skin turgor

  • Hypovolemic shock (severe cases)

Hypertonic (Hypernatremia) Dehydration

The concentration of sodium is much higher than the volume of water in your body.


Signs and Symptoms of Hypertonic Dehydration

  • Extreme thirst

  • Dark urine

  • Decrease in urination

  • Tiredness/Restlessness

  • Dry Skin

  • Headaches

  • Lightheadedness/Dizziness

  • Fatigue

  • Confusion

  • Muscle Twitches/Cramps

  • Low blood pressure

  • Tachycardia (fast heart rate)

  • Irregular heartbeat

  • Seizures (severe cases)

  • Coma or Death (extreme cases)

Hypotonic Dehydration

The concentration of sodium is much lower than the volume of water in your body.


Signs and Symptoms of Hypertonic Dehydration

  • Tiredness/Sluggishness

  • Confusion

  • Muscle Twitches/Cramps

  • Poor kidney function

  • Decrease in urination

  • Tachycardia (fast heart rate)

  • Low blood pressure (severe cases)

  • Bluish skin (severe cases)

  • Weak pulse (severe cases)

  • Seizures (severe cases)

  • Shock (severe cases)

  • Coma or Death (extreme cases)



Signs and Symptoms of Dehydration

Seek medical attention if you experience any of the following signs and symptoms:

  • Confusion

  • Dizziness/Lightheadedness

  • Fatigue

  • Dark urine

  • Decrease in urination

  • Muscle Twitches/Cramps

  • Tachycardia (fast heart rate)

  • Low blood pressure (severe cases)

  • Bluish skin (severe cases)

  • Weak pulse (severe cases)

Treatment for Dehydration

Replenish your body with water and electrolytes. Some options include electrolyte energy gels, sports drinks with electrolytes or drinking water, and consuming foods with sodium, potassium, calcium, chloride, phosphate, and magnesium. Drinking juice or pop may lead to or worsen symptoms of diarrhea.


What is Hyponatremia

When your body has an excess amount of water in relation to the concentration of sodium, your body experiences hyponatremia. The body needs electrolytes to regulate the amount of water in your body. When these levels become too low, your body becomes overwhelmed with too much water.


A normal blood sodium level is between 135 and 145 milliequivalents per liter (mEq/L). Hyponatremia occurs when the sodium in your blood falls below 135 mEq/L.


Fluid excretion can tip the scales through sweating, breathing, and urination. The common causes of hyponatremia are sweating, vomiting, diarrhea, and drinking too much water without replenishing electrolytes. There are four types of hyponatremia.


In an article, “Cost of Illness of Hyponatremia in the United States,” published by NCBI, a study was conducted to determine the annual cost to treat patients with hyponatremia. A study in 2002, estimates 3.16 million to 6.07 million people are treated for hyponatremia in the US annually.


Types of Hyponatremia

Hyponatremia can be declared as chronic or acute.


Acute Hyponatremia

Acute hyponatremia is when the sodium levels drop rapidly.


Symptomatic or Asymptomatic

According to the article, “Cost of Illness of Hyponatremia in the United States,” an estimated 1% of patients were classified as having acute and symptomatic hyponatremia and 4% were classified as acute and asymptomatic.


Sign and Symptoms of Acute Hyponatremia

  • Symptoms of CNS dysfunction

  • Impaired taste sensation

  • Muscle cramps

  • Nausea

  • Weakness

  • Confusion

  • Delirium

  • Brain swelling

  • Seizures (severe cases)

  • Coma/Death (extreme cases)

Chronic Hyponatremia