Drug monitoring is required for the following

(A) Lithium# Lithium is generally taken with food, although its absorption is not markedly affected by the presence of food.> Doses vary widely and are adjusted based on measurements of the levels of lithium in the blood.> Early in therapy, dose adjustments are made as often as every 5 to 7 days to establish the correct dose.> Patients with kidney diseases excrete less lithium from the body and, therefore, require lower doses.