Hyponatremia – Symptoms and Causes

Overview

Hyponatremia happens when sodium levels in the blood drop too low. Sodium plays a vital role in regulating water balance within and surrounding cells.

When sodium becomes diluted, water levels increase, causing cells to swell. This swelling can lead to health problems ranging from mild to severe.

Several factors can cause hyponatremia. These include:

• Certain medical conditions
• Drinking excessive amounts of water
• Some medications
• Hormonal imbalances

Treatment focuses on addressing the underlying cause. For some people, simply reducing fluid intake helps correct the imbalance. More serious cases might require:

1. Intravenous fluids with electrolytes
2. Medications to manage symptoms
3. Hospital monitoring

The severity of hyponatremia depends on how quickly it develops and how low the sodium levels fall. Medical professionals diagnose this condition through blood tests that measure electrolyte levels.

Signs and Warning Signs

When sodium levels in your blood drop too low, your body may show these signs:

• Feeling sick and throwing up
• Headache pain
• Feeling confused
• Tiredness and low energy
• Being restless or irritable
• Weak muscles, cramps, or spasms
• Seizures
• Loss of consciousness

When Medical Help Is Needed

Get emergency help right away if someone shows serious signs like vomiting, confusion, seizures, or passing out. These could mean the condition is dangerous.

Contact your doctor if you have risk factors for low blood sodium and experience mild symptoms such as nausea, headache, muscle cramps, or weakness.

Causes

Hyponatremia happens when blood sodium levels fall below 135 mEq/L, compared to the normal range of 135–145 mEq/L. This condition has several possible causes:

Medication Effects

• Water pills (diuretics)
• Antidepressants
• Pain medications

These drugs can disrupt normal kidney function and hormone processes that maintain proper sodium balance.

Organ System Problems

Certain health conditions cause fluid buildup in the body, which dilutes sodium concentrations.

• Congestive heart failure
• Kidney disease
• Liver problems

Hormone Disorders

Several hormone-related conditions can lead to low sodium.

• Syndrome of inappropriate antidiuretic hormone (SIADH) causes excessive water retention.
• Adrenal gland insufficiency (Addison’s disease) disrupts sodium/potassium balance.
• Low thyroid hormone levels.

Fluid Loss and Dehydration

Severe or ongoing:

• Vomiting
• Diarrhea
• Other causes of dehydration

These deplete electrolytes and increase antidiuretic hormone levels, affecting sodium balance.

Excessive Water Intake

Drinking too much water can overwhelm kidney function, especially during:

• Marathon running
• Triathlons
• Other endurance activities

During these activities, sodium lost through sweat, combined with high water intake, creates an imbalance.

Recreational Drug Use

The drug Ecstasy (MDMA) increases hyponatremia risk, sometimes leading to severe or fatal cases.

Risk Factors

Several factors may raise your chances of developing hyponatremia:

• Age: Older adults face greater risks due to age-related changes, medication use, and more common chronic conditions affecting sodium balance.

• Medications: Some drugs increase hyponatremia risk, including:

  • Thiazide diuretics
  • Certain antidepressants
  • Some pain medications
  • The recreational drug Ecstasy, which has been linked to fatal cases

• Medical conditions: Problems that reduce the body’s ability to excrete water properly include:

  • Kidney disease
  • Syndrome of inappropriate antidiuretic hormone (SIADH)
  • Heart failure

• Endurance activities: People who consume too much water during high-intensity, long-duration events face increased risk, including participants in:

  • Marathons
  • Ultramarathons
  • Triathlons

These risk factors often work together. For example, an older person taking certain medications might face a much higher risk than someone with only one risk factor.

Health Issues

Sodium levels that drop slowly over two days or more are called chronic hyponatremia. This condition usually causes milder symptoms and problems.

When sodium drops quickly (acute hyponatremia), the situation becomes more dangerous. The brain can swell rapidly, possibly leading to unconsciousness and even death if not treated.

Research shows that younger women before menopause face higher risks of brain damage from low sodium levels. Scientists believe female hormones may affect how the body manages sodium balance.

Risk factors by group:

• Premenopausal women – Highest risk
• Men – Moderate risk
• Elderly – Variable risk depending on health status

The speed of sodium decrease is the most important factor in determining how serious the condition becomes.

Prevention

Preventing hyponatremia involves several practical approaches that can help maintain normal sodium levels in your blood.

Address Underlying Health Issues

Getting proper treatment for conditions like adrenal insufficiency can prevent sodium imbalances. Don’t ignore symptoms that might indicate a problem with your sodium levels.

Know Your Medications

Be informed about the medications you take, especially diuretics. Talk with your healthcare provider about potential side effects and risks related to sodium levels.

Smart Hydration During Exercise

Athletes should avoid drinking excessive amounts of water. Instead, drink based on thirst and sweat loss during intense activities.

Choose Electrolyte-Containing Drinks

For endurance events like marathons or triathlons, consider sports beverages that contain electrolytes rather than plain water. These help replace what your body loses through sweat.

Water Intake Guidelines:

Indicator	What to Look For
Thirst	Minimal thirst sensation
Urine color	Pale yellow (not clear or dark)
Frequency	Consistently urinating at regular intervals without experiencing excessive urgency