What are the possible effects of Lithium levels above 2 mEq/L?

Lithium is a medication often used to treat bipolar disorder, but it has a narrow therapeutic index, meaning the difference between an effective dose and a toxic dose is small. When lithium levels exceed 2 mEq/L, toxicity can occur, leading to significant and potentially dangerous health effects.

High levels of lithium can result in central nervous system (CNS) depression, which includes symptoms such as lethargy, decreased alertness, and confusion. The risk of arrhythmias, which are irregular heartbeats, is heightened because lithium can affect cardiac function and electrolyte balance. Additionally, seizures can occur as a result of severe toxicity, reflecting a critical state of neurotoxicity.

The other options describe effects that may occur at lower lithium levels or are more associated with side effects rather than toxicity. For instance, weight gain, nausea, and tremors are common side effects of lithium, usually observed at therapeutic levels, rather than effects of hyperlipidemia. Similarly, hypertension and headaches are not typical manifestations of lithium toxicity. Thus, option B accurately highlights the severe complications that can arise when lithium levels rise significantly above the therapeutic range.