Lithium is a medication prescribed to stabilize mood, especially in bipolar disorder. It works to regulate severe shifts in mood, reducing the intensity of manic or depressive episodes. Understanding serum lithium levels, the concentration of lithium in the bloodstream, is central to treatment. Monitoring these levels ensures the medication is both effective and well-tolerated.
Why Lithium Levels Are Measured
Lithium has a narrow therapeutic window. This means there is only a small difference between an effective dose and one that could lead to harmful side effects or toxicity. Individual differences in how the body processes lithium make personalized dosing necessary.
The body’s metabolism and excretion of lithium can vary significantly from person to person. Factors like kidney function, hydration status, and age can influence how quickly lithium is cleared from the system. Without regular monitoring, it would be difficult to adjust the dosage to achieve the desired therapeutic effect while avoiding potentially dangerous levels.
Understanding Your Lithium Test Results
Lithium test results are typically reported in milliequivalents per liter (mEq/L) or millimoles per liter (mmol/L). The target therapeutic range for most individuals falls between 0.6 and 1.2 mEq/L (or mmol/L). For acute manic episodes, levels might be aimed slightly higher, often between 0.8 and 1.2 mEq/L, while for long-term maintenance, levels between 0.6 and 0.8 mEq/L are often sufficient.
A serum lithium level below the therapeutic range, generally below 0.6 mEq/L, is considered sub-therapeutic. At these levels, the medication may not be sufficient to prevent mood episodes, and you might experience a return of symptoms. This indicates the dosage may need adjustment for better symptom control.
Levels above the therapeutic range, particularly above 1.5 mEq/L, increase the risk of toxicity. Mild symptoms of toxicity can include nausea, fatigue, and a tremor. As levels increase further, moderate toxicity (2.5 to 3.5 mEq/L) can lead to confusion, increased heart rate, and issues with coordination. Severe toxicity (above 3.5 mEq/L) is a medical emergency that can involve seizures, coma, and even death.
Managing Your Lithium Levels
Several factors can influence your serum lithium levels, making consistent management important. Dehydration, whether from not drinking enough fluids, excessive sweating, vomiting, or diarrhea, can lead to increased lithium concentrations in the blood. A low-sodium diet can also cause lithium levels to rise, as the kidneys reabsorb lithium in a similar way to sodium.
Other medications can also affect lithium levels. Nonsteroidal anti-inflammatory drugs (NSAIDs), certain diuretics (like thiazides), and ACE inhibitors can increase lithium concentrations. Illnesses, especially those affecting kidney function, can also alter how the body processes lithium.
Consistent medication adherence is important for maintaining stable levels. Regular communication with your healthcare provider is also necessary. If you experience symptoms suggesting your levels might be too high or too low, or if there are changes in your health, diet, or other medications, inform your doctor promptly so they can assess and adjust your treatment as needed.