Clinical features and management of lithium poisoning

Lithium salts, in particular the carbonate and citrate, were formerly in widespread use, forming part of alkaline salt mixtures which were used for treatment of the many disorders belonging to the uric acid diathesis. Among these disorders were mania, depression, acute mania, acute melancholia and periodic depression. Satisfactory prophylactic effects on periodic depression were directly claimed. Daily doses of 3 to 26 mmol of lithium were recommended as standards. Only slight or moderate symptoms of poisoning were reported in a very few cases during the period in question (1860 to 1930), when the popularity of these lithium-containing prophylactic drugs with a favourable therapeutic index was at its peak. Lithium intoxication was not a serious clinical problem until 1949 when Cade introduced his fortuitously effective, but nevertheless high, dosage regimen which was continued until signs of recovery from mania appeared. For the maintenance dose, Cade in principle recommended, but seldom adhered to, 17 mmol/day. Chronic lithium intoxication starts insidiously with silent affliction of the kidneys followed by 'prodromal' symptoms, and when moderate severity has been reached, an accelerating renal vicious circle with decreasing kidney function is imminent. After this point the chronic intoxication resembles acute intoxication. Active detoxification at this, or an earlier stage, leaves the patient with a good chance of recovery. At a later stage, with the occurrence of oliguria, semi-coma or coma, and latent convulsive movement, recovery is less certain. There is no specific antidote for the toxic effects of lithium. Haemodialysis is the most effective treatment for acute lithium poisoning. For patients with impaired, or potentially impaired renal function, peritoneal dialysis may be an alternative, but less effective, treatment. Forced diuresis demands unimpaired renal function, and is little more effective than withdrawal of treatment, supplemented with correction of water and electrolyte balance. Sodium overloading is not recommended. Patients on lithium prophylaxis are treated on an outpatient basis. Prevention of intoxication depends on cooperation between patient and clinician, and possibly on the use of smaller, low risk dosages in most patients.