Lithium therapy is a common treatment for affective disorders and is widely regarded as a lifesaving drug. However, because its elimination is almost wholly unchanged via the kidneys, both acute and long-term adverse effects relating to toxicity may occur, including declining renal function and nephrogenic diabetes insipidus (DI). DI may be difficult to detect and is frequently preceded by dehydration and which, in our patient, was discovered by chance. We describe a case of an elderly woman on chronic lithium therapy for bipolar affective disorder who initially presented with dehydration from vomiting but possibly developed extra-pontine myelinolysis (EPM) after over-zealous correction of hyponatraemia. Steroids administered appeared to have prevented further progression but a persisting hyperosmolar state then alerted us to the presence of nephrogenic DI. Although both conditions were later successfully reversed with no obvious chronic sequelae, the recovery of the patient was protracted. Clinicians should be vigilant for complications of managing dehydration states in people prescribed with lithium.
Ten patients on long term lithium therapy (mean four years, range 1-10.5 years) were subjected to various renal, thyroid, haematological, cardiac and endocrine tests. There was impaired urinary concentrating ability in seven subjects, which was not responsive to vasopressin stimulation, suggesting a partial nephrogenic diabetes insipidus. Nine subjects had metabolic acidosis with higher urinary pH than expected suggesting presence of acidification defect in the kidney. No significant change in renal function, thyroid function, ECG or haematological parameters were detected. Our findings concur with previous reports from the West regarding the safety of lithium administration.