Lithium is a medication primarily used to manage mood disorders like bipolar disorder. For individuals taking lithium, maintaining stable blood levels is important for effectiveness and safety. Lithium operates within a narrow therapeutic window, meaning the difference between an effective and harmful dose is small. Understanding factors that can cause lithium levels to rise is crucial for patient well-being.
Physiological Conditions Affecting Lithium Levels
Several bodily states can influence lithium concentration. Dehydration directly increases lithium levels because less fluid in the body concentrates the existing lithium. This can occur from reduced fluid intake or excessive fluid loss due to sweating, fever, vomiting, or diarrhea. When the body loses water, the kidneys reabsorb more water, and since lithium is handled similarly to sodium, more lithium is also reabsorbed.
Sodium intake also plays a direct role in lithium excretion. Reduced sodium intake can lead to higher lithium levels. The kidneys work to conserve sodium, and because lithium ions can mimic sodium ions, a low-sodium diet prompts the kidneys to reabsorb more sodium, inadvertently retaining more lithium. Maintaining a consistent sodium intake is important to help stabilize lithium levels.
The kidneys are primarily responsible for filtering lithium, so impaired kidney function can cause lithium to accumulate. Conditions that affect kidney health, whether acute or chronic, can reduce the kidneys’ ability to excrete lithium effectively. Long-term lithium use can also impact kidney function, with some studies indicating a risk of chronic kidney disease over time.
Medications That Interact With Lithium
Many medications can interact with lithium, leading to elevated levels and potential toxicity. Nonsteroidal anti-inflammatory drugs (NSAIDs) can increase lithium levels by reducing blood flow to the kidneys and decreasing lithium excretion. NSAIDs, such as ibuprofen and naproxen, can increase lithium concentrations by approximately 15-60%. Acetaminophen is a safer alternative for pain relief for individuals taking lithium.
Diuretics significantly raise lithium levels. These drugs increase sodium excretion, and the body’s compensatory reabsorption of sodium in the kidneys leads to increased reabsorption of lithium. Thiazide diuretics are particularly noted for their potential to increase lithium concentrations, sometimes requiring a reduction in lithium dosage if co-administered.
Angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) can also affect kidney function and lead to increased lithium levels. When starting these medications, or adjusting their dosage, closer monitoring of lithium levels is often necessary.
Recognizing Signs of Elevated Lithium
Recognizing the symptoms of elevated lithium levels, or lithium toxicity, is important for timely intervention. Symptoms can range from mild to severe, depending on the concentration of lithium in the blood. Mild to moderate symptoms might include nausea, vomiting, diarrhea, and a fine hand tremor. Individuals may also experience increased thirst, frequent urination, muscle weakness, and drowsiness.
As lithium levels rise, symptoms can become more pronounced. These may include a worsening tremor, confusion, slurred speech, and unsteadiness or difficulty with coordination (ataxia). In severe cases, individuals might experience seizures, kidney problems, irregular heartbeats, and a reduced level of consciousness or coma. Some symptoms of mild toxicity can overlap with common lithium side effects, making medical evaluation important to determine the cause.
Steps to Take for High Lithium Levels
If elevated lithium levels or symptoms of toxicity appear, seek immediate medical attention. For severe symptoms, emergency care should be accessed without delay. Never attempt to adjust the lithium dosage independently, as this can lead to further complications or instability in mood management.
Communicate all symptoms, recent illnesses, changes in diet or hydration, and any new medications or supplements to a healthcare provider. Regular blood tests to monitor lithium levels are a standard part of treatment, ensuring the medication remains within a safe and effective range. These tests help healthcare teams make informed adjustments to dosage as needed.