Which of the following tests is crucial when monitoring patients on Lithium?

The Complete Blood Count (CBC) is important for monitoring patients on Lithium primarily to assess for potential side effects and complications associated with ongoing treatment. Although Lithium does not directly affect blood cell production, monitoring white blood cell counts can be crucial because these patients may experience changes in their blood counts over time due to other medications or underlying medical conditions.

In addition, while Lithium primarily affects renal function and electrolyte levels, the CBC can help detect any unexpected hematological side effects. Regular monitoring helps ensure that the patient remains in good health and can aid in identifying issues that could complicate treatment or signal that adjustments to the therapeutic regimen are required.

Other tests like liver enzyme panels, serum magnesium levels, or prostate-specific antigen tests do not specifically correlate with Lithium monitoring. Liver enzyme tests are generally more relevant for medications known to affect the liver, while magnesium levels and prostate-specific antigen tests relate to other health conditions or medication effects that are not as directly impacted by Lithium treatment.