lithium
Meaning of lithium: Anything shifting salt and water balance shifts lithium with it, which is why dehydration and several everyday drugs push blood levels upward.
Definition of lithium
Lithium is a soft, light metallic element whose salts, chiefly lithium carbonate, are used as a mood stabilizer. Taken over the long term it reduces both the manic and the depressive swings of bipolar disorder rather than acting on one pole alone. The margin between an effective and a toxic blood level is narrow, so treatment includes regular blood monitoring.
What is it used for?
Bipolar disorder is the main indication, both for settling an acute manic episode and, more importantly, for preventing further episodes over years. It is also added to an antidepressant in treatment-resistant depression, where it can improve response to a drug that was not working alone. Among mood stabilizers it has the strongest evidence for reducing suicide risk in bipolar disorder, an effect that appears to be separate from its effect on mood episodes. How lithium works is still not settled; it alters signaling pathways inside nerve cells rather than blocking a single receptor, which is unlike most psychiatric drugs.
What is monitored, and why?
| Check | Reason |
|---|---|
| Blood lithium level | The effective and toxic ranges sit close together |
| Kidney function | Lithium is cleared entirely by the kidneys and can impair them over long use |
| Thyroid function | It can slow the thyroid, producing tiredness and weight gain |
| Calcium | Parathyroid activity may rise, lifting blood calcium |
Levels are drawn at a standard interval after the last amount taken, since a sample timed differently is not comparable. A kidney function test is part of the same routine.
What pushes the level out of range?
The kidney handles lithium much as it handles sodium, so it is reabsorbed more avidly whenever the body is conserving salt and water. Dehydration, vomiting, diarrhea, heavy sweating, a low-salt diet and acute illness all raise the level without any change in the amount taken. Several common drugs do the same, including many anti-inflammatory painkillers, thiazide diuretics and some blood pressure medications. Rising levels produce coarse tremor, nausea, vomiting, diarrhea, slurred speech, unsteadiness and confusion, and severe toxicity can affect the kidneys and the nervous system lastingly. That interaction profile, rather than the drug being difficult in itself, is why a full medication list matters so much during lithium treatment.
Used in a sentence
Lithium was continued as part of the patient's long-term treatment plan for bipolar disorder.
Good to know
The margin between an effective and an excessive blood level of lithium is comparatively narrow, which is why periodic monitoring of lithium levels, kidney function and thyroid function is a routine part of treatment with this medication.
Word origin
Where “lithium” comes from
From Greek lithos, meaning stone, reflecting the element's original discovery within mineral rock rather than in plant or animal material.