What is Lithium Toxicity?
Lithium is the preferred medication for managing recurring bipolar disorder, a condition marked by extreme mood swings. It is a mood-stabilizing drug that is in some ways similar to sodium, but how exactly it works is not completely understood. It was first approved by the U.S. Food and Drug Administration (FDA) in the 1970s to treat mania, which is a state of extreme excitement or hyperactivity. Lithium is a powerful drug that can control mania, but it needs to be used carefully because there’s a small difference between the amount that is therapeutic (helps the symptoms) and the amount that is harmful.
The way lithium works in our body is still not clearly understood. However, several theories suggest how it might work:
* It might decrease a substance in the brain called inositol, making the brain less responsive to stimulation from substances that can cause excitement.
* It might reduce the response of brain cells to neurotransmitters – the chemicals that transmit signals in the brain – by suppressing certain proteins that are essential for the opening of ion channels, which are gateways into the cells.
* It might promote the release of serotonin, a neurotransmitter that contributes to feelings of well-being and happiness, from a part of the brain called the hippocampus.
* Being similar to sodium and potassium, it might affect the transport of ions (electrically charged particles) and the potential of cell membranes (the outer layer of the cell that controls what enters and leaves the cell).
What Causes Lithium Toxicity?
Taking too much lithium can result in a condition called lithium toxicity. There are several factors that can increase the amount of lithium in your body. These include taking in too much lithium or having difficulties in getting rid of lithium from your body.
Risk Factors and Frequency for Lithium Toxicity
A study looked at a group of patients who were treated with lithium from 1997 to 2013. The goal was to check how often lithium intoxication reoccurred and if there were any changes in the kidney function. Out of 1340 patients, 96 suffered from at least one episode of high lithium levels (more than 1.5 mmol/L). In a smaller group of 77 participants, 91 instances were recorded where 34% needed intensive care and 13% required a procedure called hemodialysis. Fortunately, no one died. Though some patients had an acute kidney injury, their kidney function remained the same after the episode.
Signs and Symptoms of Lithium Toxicity
In the late 19th century, lithia water was used to treat mania and gout. With time, it was replaced by lithium tablets with a higher lithium concentration. However, this higher concentration was linked with symptoms like tremors and weakness. In 1898, excessive amounts of lithium in the body, also known as lithium toxicity, was discovered. To identify lithium toxicity, factors such as the amount of lithium consumed, timing of consumption, the presence of other consumed substances, and whether the consumption was accidental or intentional, need to be considered. However, symptoms of lithium toxicity often do not match the measured lithium levels.
When someone has too much lithium in their system, they might experience:
- Neurological issues such as tremors, overactive reflexes, uncontrolled eye movements, and lack of coordination. They might also have varying levels of awareness, from slight confusion to delirium. In some cases, these symptoms can last up to 12 months and sometimes may not disappear.
- Risk of kidney toxicity if they’ve been taking lithium over a long period. This can include changes to urination, nephrogenic diabetes insipidus (a common issue with drug-induced NDI), sodium-losing nephritis, and nephrotic syndrome.
- Minor and non-specific effects on the heart. Patients using lithium commonly develop a flattened T wave in their electrocardiogram. Other minor issues can include malfunctioning of the sinus node, elongated QT interval, intraventricular conduction defects, and U waves. These changes typically go away when the patient is no longer exposed to lithium.
- Gastrointestinal effects usually occur within an hour of consuming lithium, more so if the individual has overdosed.
- Impact on thyroid function, as lithium inhibits the production and release of thyroid hormone, leading to hypothyroidism. It’s less common to see hyperthyroidism, but if present, it can hide symptoms of lithium toxicity and increase the toxicity as the body’s cells become unresponsive and handle lithium differently in the kidneys.
Testing for Lithium Toxicity
If you are suspected of having a lithium intoxication, your doctor will monitor your heart activity, check your oxygen levels, and keep an eye on your urine output. They will also likely order a range of blood tests to measure levels of electrolytes, calcium, glucose, kidney function, thyroid-stimulating hormone, and lithium. Please note that both regular lithium usage and intoxication can increase your white blood cell count. Furthermore, taking a large amount of lithium carbonate can sometimes mess with the calculation of your anion gap, potentially leading to low results.
Chronic lithium use can also make kidneys less efficient, leading to high levels of blood urea nitrogen and creatinine. If your doctor is having trouble making a clear diagnosis, they might order brain imaging.
The standard level for lithium in the blood is approximately 0.6 to 1.2 mEq/L. It’s important to measure the lithium levels in your blood at least 6 to 12 hours after your last dose to avoid misinterpretation of the results.
It’s also worth noting that some tests use a form of lithium called lithium heparin to stop blood samples from clotting, which can result in artificially high results for lithium levels in the blood.
Treatment Options for Lithium Toxicity
Decontamination involves removing harmful substances that may have been ingested. From laboratory studies, we know that a substance called activated charcoal doesn’t do a good job of sticking to lithium, a medication sometimes taken in overdose. However, if we’re unsure whether other substances have been ingested along with lithium, activated charcoal should be given. In cases where regular-release forms of the medication were taken, or if the patient arrives at the ER soon after ingesting the lithium, gastric lavage (stomach washing) should be considered. If the patient took extended-release forms of the lithium, or if they ingested large amounts of the regular-release forms, flushing the entire digestive tract (whole-bowel irrigation) should be thought about too.
For eliminating lithium from the body, the most efficient way is through hemodialysis. Hemodialysis is a procedure where a machine filters the patient’s blood, removing harmful wastes, chemicals, and excess fluid. Hemodialysis is particularly needed in patients showing severe lithium poisoning symptoms or those with kidney failure. You see, lithium is not bound tightly to the proteins in the blood and doesn’t distribute widely in the body, making it easier to clear with hemodialysis. Conversely, peritoneal dialysis, another method of cleaning the blood, should only replace hemodialysis if the latter is unavailable, for example, in remote areas.
All patients demonstrating signs of lithium toxicity should be admitted to the hospital for monitoring, even if their blood lithium levels are within the normal range. If the poisoning symptoms are moderate to severe, the patient should be monitored in an intensive care unit. It would help if you had blood tests every 6 hours to check your lithium levels if you don’t have symptoms after ingesting a large amount of lithium. This should be continued until it is confirmed that the lithium levels are dropping. Discharge from the hospital would only be considered once the patient is symptom-free, and their lithium blood level is less than 1.5 milliequivalents per liter.
What else can Lithium Toxicity be?
Some conditions that can cause similar symptoms to acute hypoglycemia include:
- Alcohol toxicity
- Anticholinergic toxicity (reaction to certain medications)
- Delirium
- Dementia
- Depression
- Heavy metal toxicity
- Mercury toxicity
- Neuroleptic agent toxicity (reaction to certain medications)
- Ischemic stroke (a blockage in the blood supply to the brain)
It’s crucial to identify the correct cause of the symptoms for accurate treatment.
What to expect with Lithium Toxicity
Too much lithium in your body, known as lithium toxicity, is a serious condition that should not be ignored, it can potentially be life-threatening. In severe cases, lithium toxicity can cause serious illness, such as coma, brain damage, or even death. Plus, lithium can trigger a dangerous condition called serotonin syndrome, which can be life-threatening.
When lithium is taken together with specific types of drugs, which either increase serotonin levels (a chemical in the brain that helps regulate mood) or block the breakdown of serotonin, it can heighten the risk of developing serotonin syndrome.
Possible Complications When Diagnosed with Lithium Toxicity
The degree of poisoning is crucial for diagnosing and managing lithium toxicity.
Lithium toxicity has three levels: mild, moderate and severe.
- Mild symptoms include feeling sick, throwing up, feeling tired and shaky. These symptoms occur when the lithium concentration in the blood is between 1.5-2.5 mEq/L.
- Moderate poisoning shows as confusion, restlessness, hallucinations, rapid heartbeat, and muscle tension. These symptoms are seen when the lithium levels are between 2.5-3.5 mEq/L.
- Severe poisoning can cause comas, seizures, extreme body temperature, and low blood pressure. This happens when blood lithium levels exceed 3.5 mEq/L.