This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Central Nervous system, Subject name: Pharmacology
A psychiatric patient taking medication develops a tremor, thyroid enlargement and leucocytosis. Drug implicated is 
Select and explain. 
A. Clomipramine, B. Haloperidol, C. Lithium, D. Olanzapine
C: Lithium
Answer: C: Lithium 
Explanation: Tremor is one of the most common adverse effects of lithium treatment, and it occurs with therapeutic doses.Lithium probably decreases thyroid function in most patients exposed to the drug,Leukocytosis is always present during lithium treatment, probably reflecting a direct effect on leukopoiesis rather than mobilization from the marginal pool.Polydipsia and polyuria, Edema are other adverse effectsReference: Katzung Pharmacology; 12th edition; Page no: 517