Lithium and renal function in relation to concomitant theory

Two hundred and fourteen patients (99 men, 115 women, age 21-87 years) were treated with lithium during the period 1963-1984 at the Psychiatric Unit, Danderyd Hospital. The patients were diagnosed as having bipolar depression (97), unipolar depression (54), cycloid psychosis (21), schizoaffective psychosis and depressive neurosis (42). Sixty patients were treated with lithium salt only, 73 patients received neuroleptic drugs in addition to lithium and 51 antidepressant drugs. Sixteen patients were treated with a combination of neuroleptic drugs, antidepressant drugs and lithium. Fourteen patients were treated with lithium and benzodiazepines. The aim of this retrospective lithium study was to examine the renal function in these different treatment groups. The results show that patients treated with a lithium salt and neuroleptic drugs have significantly lower urinary osmolality than those treated with a lithium salt only. Also tricyclic antidepressants in combination with a lithium salt appear to have an influence on renal function. The duration of concomitant therapy seems to be of importance for the effect on renal function. Eleven patients with the lowest osmolality values were investigated at the Renal Unit, Danderyd Hospital, but in no case was it necessary to withdraw the lithium treatment.