Can Lyme Disease Cause Low Sodium? SIADH and Lyme Meningitis
Can Lyme disease lower sodium levels?
It may signal meningitis.
And it is often missed.
Lyme low sodium SIADH can occur when Lyme meningitis affects the central nervous system and disrupts fluid balance.
Low sodium levels are often attributed to medications or endocrine disorders.
But in some cases, persistent hyponatremia may be a clue to an underlying infection—particularly involving the brain or nervous system.
This is where Lyme disease can be overlooked.
Quick Answer: Can Lyme Disease Cause SIADH?
Yes. Lyme meningitis can trigger SIADH (syndrome of inappropriate antidiuretic hormone secretion), leading to low sodium levels.
This typically occurs when the infection affects the central nervous system.
Case Example: Low Sodium With No Clear Cause
An 83-year-old woman developed persistent hyponatremia (125–126 mmol/L).
Her symptoms included:
- Back and shoulder pain
- Difficulty concentrating
- Unsteadiness
- Poor appetite
Initially, her low sodium was attributed to medication.
But her sodium levels did not improve after medication changes.
The Missing Diagnosis: Lyme Meningitis
A lumbar puncture was eventually performed.
It confirmed Lyme meningitis.
After three weeks of antibiotic treatment, her sodium levels normalized.
This supports a diagnosis of SIADH caused by central nervous system infection.
Learn more about neurologic Lyme disease.
Why Lyme Disease Can Cause Low Sodium
SIADH occurs when excess antidiuretic hormone causes the body to retain water.
This dilutes sodium levels in the blood.
In Lyme meningitis, possible mechanisms include:
- Central nervous system inflammation
- Disruption of hypothalamic regulation
- Increased intracranial pressure
- Systemic inflammatory effects
The result is persistent, unexplained hyponatremia.
Why This Diagnosis Is Often Missed
Hyponatremia is common and has many causes.
Clinicians often focus on:
- Medications
- Endocrine disorders
- Fluid imbalance
Infection—especially Lyme disease—is not always considered.
This contributes to Lyme disease misdiagnosis.
Clinical Clues to Watch For
Consider Lyme meningitis when hyponatremia occurs alongside:
- Back or radicular pain
- Cognitive changes
- Balance problems
- Unexplained neurologic symptoms
These features may point to neuroborreliosis rather than a metabolic cause alone.
Clinical Perspective
Hyponatremia may be an early metabolic clue to Lyme neuroborreliosis.
When sodium remains low despite standard interventions, clinicians should broaden the differential diagnosis.
In endemic areas, Lyme disease should be considered—especially when neurologic symptoms are present.
Clinical Takeaway
Persistent low sodium (SIADH) can be a sign of Lyme meningitis.
When hyponatremia does not respond to standard treatment—especially with neurologic symptoms—Lyme disease should be considered.
Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.
Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention
Hello Dr. Cameron. I am an old patient Dr. Glenn Askedall disabled for years with chronic lyme or bartonella. A strange thing happened to me. I had to go for an mri of my prostate which turned out to be a small cancerous tumor which is now gone with the proton therapy I received. The reason for this post is that when I went for the mri the nurses could not get an iv started. I suffer from what I think is hypovolemia. After the fourth jab they got an IV and gave me a bag of ringers solution. For the next two days I felt absolutely great! About 99% of my symptoms were gone for two days. I have not felt well since this IV last summer. I wish I could receive this IV again!!