A clinico-pathological study of lithium nephrotoxicity.

Lithium salts, well recognised as acute nephrotoxins, have recently been implicated in the development of a chronic focal interstitial nephropathy. As part of a clinico-pathological study of lithium nephrotoxicity, renal function and renal histology has been compared between 25 patient on maintenance lithium therapy and 19 patients with affective illnesses prior to commencement of lithium therapy. Significant evidence of chronic renal damage was present in biopsies of lithium treated patients when compared with cadaveric donor kidneys (p less than 0.001). Similar damage was noted in biopsies from patient prior to lithium and differed from donor kidneys (p less than 0.01). The degree of damage was not significantly different between the patients on lithium and those not yet on lithium. An acute specific tubular lesion was note in patients on lithium, and a marked degree of distal tubule dilation and microcyst formation were also observed. Significant defects in urinary concentrating ability and urinary acidification were present in patients on lithium and there was a correlation between the degree of these defects and the duration of lithium therapy. There was no evidence of a substantial reduction in glomerular filtration rate, which could be ascribed to the lithium therapy.