Which symptom is NOT associated with lithium toxicity above 1.5 mEq/L?

The correct response highlights that insomnia is not typically regarded as a symptom of lithium toxicity at levels exceeding 1.5 mEq/L. In contrast, ataxia, coarse hand tremors, and seizures are recognized signs associated with lithium toxicity.

Ataxia relates to a lack of muscle control or coordination of voluntary movements, which can occur as lithium levels rise, affecting the central nervous system. Coarse hand tremor is a common initial sign of toxicity, reflecting the drug's impact on neuromuscular function. Seizures indicate severe toxicity and suggest significant central nervous system impairment. Insomnia, while it may present in various psychiatric contexts, is not directly linked to lithium toxicity and is therefore an outlier in this context. This distinction is crucial for recognizing the clinical presentation and management of lithium toxicity, as understanding the specific symptoms helps guide appropriate interventions.