This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Psychiatry
Which of the following represent the theraputic level of Lithium in serum? 
Select and explain. 
A. 0.8 - 1.2 meq/l, B. 0.6 - 1.2 meq/l, C. >2 meq/l, D. None
A: 0.8 - 1.2 meq/l
Answer: A: 0.8 - 1.2 meq/l 
Explanation: Lithium is most commonly used in the treatment of bipolar depression. It has a low toxic : therapeutic ratio. The therapeutic level of Lithium in serum is 0.8 - 1.2 mEq/L. Lithium toxicity occur when serum lithium levels exceed 1.5 to 2 mEq/L. Hence frequent bood tests are done to monitor the drug levels. Lithium is fully metabilised by the kidney. Hence, dehydration could cause the drug levels to rise. Ref: Current Medical Diagnosis and Treatment 2013, chapter 38.