[Renal and metabolic complications of lithium]

Renal and metabolic adverse effects of lithium therapy are illustrated by the case report of a manic depressive woman aged 78 years, so treated for about 25 years. Long term lithium therapy with plasma lithium level in the therapeutic range impairs renal concentrating ability in 25-50% of the patients (when the total ingested amount reaches 100-200 mol, 700-1400 g). About 10-15% of the patients have overt nephrogenic diabetes insipidus (NDI) with elevated antidiuretic hormone plasma level and unresponsiveness to desmopressin. In rats, lithium treatment down regulates expression of the main water channel, aquaporin 2, in the renal collecting duct. NDI may be complicated by hypernatremic dehydration if the access to water is restricted, whatever the cause. Treatment of NID is best started with nonsteroidal antiinflammatory drugs, being then substituted for amiloride. Prolonged lithium therapy may induce chronic interstitial nephritis. In some patients this may result in mild or moderate non progressive chronic renal insufficiency. Acute lithium intoxication (with supratherapeutic doses) may be complicated by acute renal failure (ARF); even in the absence of ARF hemodialysis is indicated when plasma lithium level reaches 4 mmol/l or more. Other metabolic adverse effects of lithium therapy include: hypercalcemia due to hyperparathyroidism (in 5-10% of the patients); hypothyroidism (often latent); hyperthyroidism. In conclusion, these renal and metabolic adverse effects are generally mild or moderate, allowing the continuation of lithium therapy in most affected patients.