Understanding Low Sodium (Hyponatremia): Symptoms & Effects
What Is Hyponatremia?
Hyponatremia is when blood sodium levels fall below 135 mmol/L, disrupting the balance of water and electrolytes in the body. Severe cases are those under 120 mmol/L.
Symptoms & Neurological Effects
- Disorientation & Time/Place Confusion
- Confusion, disorientation, and loss of orientation are common, particularly in moderate to severe cases.
- Hyponatremia—especially when triggered by SIADH (syndrome of inappropriate antidiuretic hormone)—can also cause memory impairment, personality alterations, delirium, and hallucinations.
- Behavioral or Personality Changes
- Symptoms may include irritability, depressed mood, lethargy, psychosis, or personality changes.
- Loss of Sense of Time and Place
- Disorientation to time and place can occur as part of the broader cognitive decline brought on by sodium imbalance.
- Attention Deficits & Cognitive Slowness
- Even mild or chronic hyponatremia can lead to subtle but significant issues: attention deficits, slowed thinking, lethargy, restlessness, and gait unsteadiness.
Underlying Mechanism: Why These Symptoms Occur
- Water shifts into brain cells cause cerebral swelling (edema), leading to neurological symptoms such as confusion or disorientation. The brain attempts to adapt by shedding osmolytes (like glutamate and inositol), but this can disrupt neural function and synaptic signaling.
- In chronic, gradual hyponatremia, this adaptation may mask obvious symptoms but still impair balance, cognition, and attention.
