Several clinical scenarios of lithium toxicity can occur such as acute overdose in a suicidal patient, acute on chronic toxicity in patients taking lithium whose renal function has declined (e.g., patients with gastroenteritis, decreased oral intake, and patients concomitantly taking other medications such as nonsteroidal anti-inflammatory drugs and angiotensin converting enzyme inhibitors), and chronic toxicity in patients who slowly accumulate the medication and develop toxicity [14, 57]. This evidence concerns the gene ACE and gastroenteritis.