Lithium is sometimes used as an augmenting agent to increase the benefits of standard drugs used for unipolar depression. Lithium treatment was previously considered to be unsuitable for children; however, more recent studies show its effectiveness for treatment of early-onset bipolar disorder in children as young as eight. The required dosage (15–20 mg per kg of body weight) is slightly less than the toxic level, requiring blood levels of lithium to be monitored closely during treatment. To prescribe the correct dosage, the patient's entire medical history, both physical and psychological, is sometimes taken into consideration. The starting dosage of lithium should be 400–600 mg given at night and increased weekly depending on serum monitoring.[9]
Those who use lithium should receive regular serum level tests and should monitor thyroid and kidney function for abnormalities. As it interferes with the regulation of sodium and water levels in the body, lithium can cause dehydration. Dehydration, which is compounded by heat, can result in increasing lithium levels. The dehydration is due to lithium inhibition of the action of antidiuretic hormone, which normally enables the kidney to reabsorb water from urine. This causes an inability to concentrate urine, leading to consequent loss of body water and thirst.[10]
High doses of haloperidol, fluphenazine, or flupenthixol may be hazardous when used with lithium; irreversible toxic encephalopathy has been reported.[11]
Lithium salts have a narrow therapeutic/toxic ratio and should therefore not be prescribed unless facilities for monitoring plasma concentrations are available. Patients should be carefully selected. Doses are adjusted to achieve plasma concentrations of 0.4[12][13] to 1.2 mmol Li+/l (lower end of the range for maintenance therapy and elderly patients, higher end for pediatric patients) on samples taken 12 hours after the preceding dose. Overdosage, usually with plasma concentrations over 1.5 mmol Li+/L, may be fatal, and toxic effects include tremor, ataxia, dysarthria, nystagmus, renal impairment, confusion, and convulsions. If these potentially hazardous signs occur, treatment should be stopped, plasma lithium concentrations redetermined, and steps taken to reverse lithium toxicity. The most common side effects are an overall dazed feeling and a fine hand tremor. These side effects are generally present during the length of the treatment, but can sometimes disappear in certain patients. Other common side effects, such as nausea and headache, can be generally remedied by a higher intake of water. Lithium unbalances electrolytes; to counteract this, increased water intake is suggested.
Lithium toxicity is compounded by sodium depletion. Concurrent use of diuretics that inhibit the uptake of sodium by the distal tubule (e.g. thiazides) is hazardous and should be avoided. In mild cases, withdrawal of lithium and administration of generous amounts of sodium and fluid will reverse the toxicity. Plasma concentrations in excess of 2.5 mmol Li+/l are usually associated with serious toxicity requiring emergency treatment. When toxic concentrations are reached, there may be a delay of one or two days before maximum toxicity occurs.
In long-term use, therapeutic concentrations of lithium have been thought to cause histological and functional changes in the kidney. The significance of such changes is not clear, but is of sufficient concern to discourage long-term use of lithium unless it is definitely indicated. Doctors may change a bipolar patient's medication from lithium to another mood-stabilizing drug, such as valproate (Depakote), if problems with the kidneys arise. An important potential consequence of long-term lithium use is the development of renal diabetes insipidus (inability to concentrate urine). Patients should therefore be maintained on lithium treatment after three to five years only if, on assessment, benefit persists. Conventional and sustained-release tablets are available. Preparations vary widely in bioavailability, and a change in the formulation used requires the same precautions as initiation of treatment. There are few reasons to prefer any one simple salt of lithium; the carbonate has been the more widely used, but the citrate is also available.
Lithium may be used as a treatment of seborrhoeic dermatitis (lithium gluconate 8% gel). In addition, lithium has been shown to increase production of white blood cells in the bone marrow and might be indicated in patients suffering from leukopenia.[14]
A limited amount of evidence suggests lithium may contribute to treatment of substance abuse for some dual-disorder patients.[15][16][17]
In 2009, Japanese researchers at Oita University reported low levels of naturally occurring lithium in drinking water supplies reduced suicide rates.[18] A previous report had found similar data in the American state of Texas.[19] In response, psychiatrist Peter Kramer raised the hypothetical possibility of adding lithium to drinking water as a mineral supplement rather than as a therapeutic drug.[20] This is analogous to niacin, where a low dose in multivitamin pills is taken as a vitamin supplement to prevent the niacin deficiency disease pellagra, but a high dose is prescribed as a therapeutic drug to raise high-density lipoprotein ("good" cholesterol) levels.
In the treatment of bipolar disorder, lithium compounds continue to be the standard against which newer medications are measured. Lithium salts may also be helpful for related diagnoses, such as schizoaffective disorder and cyclic major depression. The active principle in these salts is the lithium ion Li+, although detailed mechanisms are debated.