Water is essential for life. The human body is made up of approximately 60% water. Every system and organ requires water to function properly. However, it is possible to drink too much water which can lead to negative side effects. While staying hydrated is important, overhydration presents risks that need to be considered.
What is overhydration?
Overhydration occurs when the intake of fluid, especially water, exceeds the kidney’s ability to excrete water. The excess water dilutes the sodium content in blood plasma, which leads to hyponatremia. Hyponatremia is characterized by an abnormally low concentration of sodium in the blood.
The normal range for blood sodium concentration is 135-145 milliequivalents per liter (mEq/L). Hyponatremia occurs when the sodium level drops below 135 mEq/L. The lower the sodium concentration falls, the more severe the condition. When sodium levels fall below 120 mEq/L, severe neurological symptoms can occur.
Consuming too much water is the most common cause of hyponatremia. Endurance athletes who drink water excessively to avoid dehydration can develop hyponatremia. However, there are other causes:
- Prolonged, heavy sweating can cause excessive loss of sodium.
- Using diuretics or water pills excessively can flush out too much sodium.
- Some medical conditions like heart failure, liver failure, and kidney disease can lead to low sodium.
- Drinking too much water because of a compulsive need to consume excessive amounts of fluid is a condition called psychogenic polydipsia.
The symptoms of hyponatremia can range from mild to severe based on how low the sodium levels fall. Symptoms may include:
- Loss of appetite
- Muscle weakness or cramps
Mild signs like headache, nausea and fatigue can occur when sodium concentrations are slightly low between 130-135 mEq/L. Moderate hyponatremia between 120-130 mEq/L can cause muscle spasms, vomiting, headache and confusion. When sodium levels fall below 120 mEq/L, it is considered severe hyponatremia which can lead to seizures, coma and respiratory arrest.
Who is at risk?
Certain groups of people are at higher risk for developing hyponatremia if they drink too much water. These include:
- Infants and young children
- Elderly adults
- Endurance athletes
- People with chronic medical conditions like heart, liver or kidney disease
- People taking medications like antidepressants, pain relievers, some blood pressure medications
Infants and young children have lower overall water needs. Elderly adults may have impaired thirst regulation and decreased glomerular filtration rate. Endurance athletes tend to overconsume water. Individuals taking certain medications may have increased antidiuretic hormone levels.
If left untreated, the complications of severe hyponatremia can be life-threatening. Low sodium disrupts the balance of fluids in the body leading to swelling in the brain and other vital organs. This can impair their functioning.
Possible complications include:
- Cerebral edema – Fluid accumulation in the brain causes swelling and elevation in pressure inside the skull. This damages brain tissue.
- Noncardiogenic pulmonary edema – Fluid builds up outside the blood vessels of the lungs making breathing difficult.
- Osmotic demyelination syndrome – Damage to the myelin sheath around nerves impairs nervous system signalling, leading to paralysis.
- Rhabdomyolysis – Breakdown of damaged muscle tissue releases proteins and electrolytes into the blood which can damage the heart and kidneys.
- Coma and death – In severe cases, respiratory arrest and brain herniation can occur leading to coma and death.
Doctors may suspect hyponatremia based on symptoms and medical history. Diagnostic tests that can confirm the condition include:
- Blood tests – Measuring sodium levels in the blood serum will show abnormally low sodium levels below 135 mEq/L.
- Urine tests – Urine osmolality and specific gravity will be lower than normal.
- Imaging – CT or MRI scans of the brain may show cerebral edema in severe hyponatremia.
Once overhydration is diagnosed, determining the underlying cause will guide the proper treatment.
Treatment focuses on raising sodium levels carefully and resolving the fluid imbalance.
- Fluid restriction – Preventing further water intake allows kidneys to excrete excess fluid.
- Salt tablets or IV saline – Increasing sodium levels must be done slowly to avoid complications.
- Diuretics – Medications help remove excess water through urination.
- Treating underlying conditions – Any medical disorders contributing to hyponatremia are addressed.
- Medication adjustment – Lowering or stopping medicines that can cause low sodium may be required.
In severe hyponatremia, hypertonic saline may be administered intravenously to raise sodium faster. Osmotic demyelination syndrome is a risk if sodium is corrected too quickly. Hospitalization for monitoring and supportive care may be necessary in severe cases.
Preventing overhydration involves being aware of fluid needs and avoiding excessive water intake. Some tips include:
- Drink when thirsty rather than forcing constant fluid intake.
- Avoid drinking over 0.9-1.4 liters of fluids per hour during exercise.
- Monitor urine color to avoid clear urine signaling overhydration.
- Avoid fluid overconsumption when taking certain medications.
- Limit water intake in children and elderly adults.
- Avoid excessive alcohol intake which can increase urination.
Consuming proper electrolyte containing fluids and monitoring sodium levels can prevent hyponatremia in at-risk individuals.
Drinking an excessive amount of water can lead to overhydration or hyponatremia, characterized by dangerously low sodium levels in the blood. Even mild hyponatremia can cause uncomfortable symptoms while severe cases can lead to life-threatening complications if left untreated. At-risk groups like infants, elderly adults and endurance athletes need to be especially cautious to avoid overhydration. Preventing excess water consumption and being aware of individual fluid needs can help avoid the dangers of drinking too much water.