Hi there ,
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Well, serum lithium levels need to be maintained between 0.6 - 0.12 meq/l, in order , for lithium to act to its full ptency as a mood stabilizer and prevent both manic as well as depressive epsiodes . Since your serum lithium levels is 0.47 , which is less than the desired level,so that lithium can control your symptoms well , and as a result of less serum lithium , your condition is swaying towards depression , and thus you are feeling tired , lethargic, dizzy . So i agree with your doctor , and as he has mentioned to increase the dose to 600 mg , twice a day , you should carry it out , this will increase the serum levels of lithium , and thus the potency and action of lithium will reach to the optimum , and your present symptoms will be allayed.
I am mentioning below a link which will throw more light on the serum lithium levels .
I wish you best of health. Take care..
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