Urinary beta-hexosaminidase excretion in patients treated with lithium, thymoleptic and/or neuroleptic drugs.

In order to evaluate the nephrotoxic effect of serum lithium within the therapeutical range, the urinary excretion of beta-hexosaminidase was studied in 44 well-managed long-term lithium treated patients and in 27 healthy controls. In addition, six patients on thylmoleptic and 16 patients on neuroleptic drugs were studied. The enzyme excretion was slightly increased in the lithium treated patients, but not in the patients only treated with thymoleptic or neuroleptic drugs. The findings are consistent with the suggestion that long-term lithium treatment causes a slowly progressive nephropathy. To follow the urinary beta-hexosaminidase excretion might be a measure to identify patients at higher risk. In two cases of lithium intoxication the enzyme excretion was considerably increased.