In The Lancet Psychiatry, Filip Fransson and colleagues 1 have undertaken an in-depth examination of kidney function in people treated with lithium in two large representative cohorts in Sweden. 1 In more than 2200 participants, the authors compared individuals with bipolar disorder or schizoaffective disorder with the general population, finding that lithium was associated with steeper declines in estimated glomerular filtration rate (eGFR) and was found to contribute to chronic kidney disease. First, the authors found a steeper eGFR decline in patients than in controls, with this difference seemingly explained by lithium use. Lithium use was associated with an additional eGFR deterioration of 0·54mL/min/1·73m2 per year treated (R2=0·37). However, the effect of lithium on eGFR showed high interindividual variation, and this pattern was only significant for people taking lithium for more than 10 years. Of 22 chronic kidney disease cases, ten (45%) were definitively caused by lithium, with five (23%) partially attributable to lithium, and seven (32%) not attributable. Of cases not attributable to lithium, four (57%) had not been exposed to lithium, and two (67%) of the three who were exposed had lithium incorrectly recorded as the cause of chronic kidney disease on their medical records. Wrongful attribution of chronic kidney disease as being lithium induced is concerning, as this appears to occur routinely, albeit infrequently.