Serum concentration of lithium may change according to mood states in bipolar patients, leading to reduced serum levels of lithium during manic periods.

Documentation of mood states and serum lithium levels in a rapid cycling patient

We report about a 58 year old female patient with rapid cycling disorder whose mood altered every 20 to 30 days. No treatment has been effective until now. The patient is treated with a stable combination of clozapine 200mg, valproate 1500mg and lithium carbonate 450mg. Noncompliance can be ruled out since intake of medication is supervised. For 13 months a mood diary was performed by a relative using a simple scale for mood which rated neutral mood with 0, mania with +1, +2 and +3 (highest mania) and depression from -1 to -3 (deepest depression). Lithium levels were obtained first on a monthly, later on a weekly to two-weekly basis.

Over a period of 13 months 7 depressive and 6 manic phases could be observed. The patient spent 230 (48%) days in depression (8 lithium samples obtained), 137 (29%) in mania (11 samples) and was euthymic on 68 (16%) days (2 samples). Mean lithium serum levels were 0.68mmol/l in depressive states, 0.37 mmol/l in manic states (p=.001, t-test). The lowest value was 0.13mmol/l (in mania) and the highest 0.93mmol/l (in depression).

In this patient mood-dependent changes of serum lithium levels during constant medication could be demonstrated. The reasons for this phenomenon are yet to be elucidated.