Lithium Toxicity
The likelihood of toxicity increases with increasing serum lithium levels. Serum lithium levels greater than 1.5 mEq/mL carry a greater risk than lower levels. However, patients sensitive to lithium may exhibit toxic signs at serum levels below 1.5 mEq/mL.
Diarrhea, vomiting, drowsiness, muscular weakness and lack of coordination may be early signs of lithium toxicity, and can occur at lithium levels below 2.0 mEq/mL. At higher levels, giddiness, ataxia, blurred vision, tinnitus and a large output of dilute urine may be seen. Serum lithium levels above 3.0 mEq/mL may produce a complex clinical picture involving multiple organs and organ systems. Serum lithium levels should not be permitted to exceed 2.0 mEq/mL during the acute treatment phase.
Fine hand tremor, polyuria and mild thirst may occur during initial therapy for the acute manic phase, and may persist throughout treatment. Transient and mild nausea and general discomfort may also appear during the first few days of lithium administration.
These side effects are an inconvenience rather than a disabling condition, and usually subside with continued treatment or a temporary reduction or cessation of dosage. If persistent, a cessation of dosage is indicated.
The following adverse reactions have been reported and do not appear to be directly related to serum lithium levels.
Neuromuscular:
Tremor, muscle hyperirritability (fasciculations, twitching, clonic movements of whole limbs), ataxia, choreo-athetotic movements, hyperactive deep tendon reflexes.
Central Nervous System:
Blackout spells, epileptiform seizures, slurred speech, dizziness, vertigo, incontinence of urine or feces, somnolence, psychomotor retardation, restlessness, confusion, stupor, coma, acute dystonia, downbeat nystagmus.
Cardiovascular:
Cardiac arrhythmia, hypotension, peripheral circulatory collapse, sinus node dysfunction with severe bradycardia (which may result in syncope), unmasking of Brugada Syndrome (See
WARNINGS: Unmasking of Brugada Syndromeand PRECAUTIONS: Information for the Patients).
Neurological:
Cases of pseudotumor cerebri (increased intracranial pressure and papilledema) have been reported with lithium use. If undetected, this condition may result in enlargement of the blind spot, constriction of visual fields and eventual blindness due to optic atrophy. Lithium should be discontinued, if clinically possible, if this syndrome occurs.
Gastrointestinal:
Anorexia, nausea, vomiting, diarrhea.
Genitourinary:
Albuminuria, oliguria, polyuria, glycosuria.
Dermatologic:
Drying and thinning of hair, anesthesia of skin, chronic folliculitis, xerosis cutis, alopecia and exacerbation of psoriasis.
Autonomic Nervous System:
Blurred vision, dry mouth.
Thyroid Abnormalities:
Euthyroid goiter and/or hypothyroidism (including myxedema) accompanied by lower T3 and T4. Iodine 131 uptake may be elevated. (See
PRECAUTIONS). Paradoxically, rare cases of hyperthyroidism have been reported.
EEG Changes:
Diffuse slowing, widening of frequency spectrum, potentiation and disorganization of background rhythm.
EKG Changes:
Reversible flattening, isoelectricity or inversion of T-waves.
Miscellaneous:
Fatigue, lethargy, transient scotomata, dehydration, weight loss, tendency to sleep.
Miscellaneous Reactions Unrelated to Dosage are:
Transient electroencephalographic and electrocardiographic changes, leucocytosis, headache, diffuse non-toxic goiter with or without hypothyroidism, transient hyperglycemia, generalized pruritis with or without rash, cutaneous ulcers, albuminuria, worsening of organic brain syndromes, excessive weight gain, edematous swelling of ankles or wrists, and thirst or polyuria, sometimes resembling diabetes insipidus, and metallic taste.
A single report has been received of the development of painful discoloration of fingers and toes and coldness of the extremities within one day of the starting of treatment of lithium. The mechanism through which these symptoms (resembling Raynaud’s Syndrome) developed is not known. Recovery followed discontinuance.