MRI findings and renal function in patients on lithium therapy

Lithium is one of the most effective medications in the treatment of mood disorders. The long-term lithium therapy can alter kidney morphology and function.

To evaluate the relation of Magnetic resonance imaging (MRI) of the kidneys and renal function in patients undergoing chronic lithium therapy.

Thirty five consecutive patients with mood disorders who were undergoing lithium therapy for at least two years were evaluated with a 1.5 tesla MR imaging and renal function tests. The relationship between renal size, the presence, number and location of renal microcyst with renal function were evaluated. The partial correlation analysis was performed to assess correlation between variables.

The mean size of kidney was 106.0 mm ± 6.0 and 106.0 mm ± 11.0 in right and left kidneys respectively. The mean number of microcysts in both kidneys was 6.2. There was a positive correlation between duration of lithium treatment and number of renal microcyst (P-value=0.03). Correlation between MRI findings and renal function tests was not statistically significant.

The present study revealed that longer duration of lithium therapy can increase number of renal microcysts which is well shown with MR imaging. It seems that increasing renal microcysts may not be consistent with renal function impairment especially in earlier treatment phase. Thus the question arises is that MRI may not be as the first line method for clinicians who aim to assess renal function during long term lithium therapy.