A patient shows which of the following symptom of overdose of lithium?

AIIMS Rishikesh & Jodhpur NO - 2017

Pharmacology

Hard

Appeared in: AIIMS Rishikesh & Jodhpur NO - 2017

Explanation

Slurred speech (dysarthria) is a key neurological symptom indicating moderate to severe lithium toxicity.
It appears as serum lithium levels rise, typically in the range of 1.5-2.0 mEq/L and above, reflecting central nervous system impairment.
The presence of slurred speech, along with other neurological signs like ataxia and coarse tremor, signals a medical emergency requiring immediate intervention to prevent progression to seizures, coma, and death.

Option A: Polyuria (increased urination) is a very common, long-term side effect of lithium therapy due to its impact on kidney function (nephrogenic diabetes insipidus). It is not considered a specific sign of acute overdose or toxicity.
Option B: Lithium is commonly associated with weight gain, not weight loss. This side effect is thought to be related to its effects on carbohydrate metabolism, increased thirst leading to high-calorie fluid intake, and potential hypothyroidism.
Option C: Lithium does not cause leukocytopenia (a decrease in white blood cells). In fact, it often causes a benign leukocytosis (an increase in white blood cells), an effect that is sometimes used off-label to treat certain conditions.

Clinical Relevance

Nursing practice connection: Use the key finding related to Symptoms of Lithium Toxicity to guide bedside assessment, documentation, and the next nursing action.
Nurses must educate patients on the subtle but critical differences between expected side effects (like fine tremor, mild thirst) and early signs of toxicity (coarse tremor, confusion, slurred speech).
Lithium has a very narrow therapeutic window (typically 0.6-1.2 mEq/L), making regular blood level monitoring and patient assessment essential for safety.
What if? If the patient reported a fine hand tremor and increased thirst instead of slurred speech, the nurse would recognize these as common therapeutic side effects. The appropriate action would be to document the findings, reassure the patient, assess for dehydration, and ensure the next scheduled lithium level check is performed, rather than initiating emergency protocols for acute toxicity.

How to Approach the Question

First, identify the core of the question: it's asking for a symptom of lithium overdose (toxicity), not just a side effect.
Next, recall the key difference between lithium's common side effects and its toxicity symptoms. Side effects can occur at therapeutic levels, while toxicity symptoms indicate a dangerous, elevated level.
Evaluate each option against this framework:
Is polyuria a sign of overdose? No, it's a common side effect.
Is weight loss a sign of overdose? No, lithium causes weight gain.
Is leukocytopenia a sign of overdose? No, lithium can cause the opposite (leukocytosis).

Concept Tested & Keywords

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E6 Kaplan Sadock's Synopsis of Psychiatry-2022 (pp 1-3768 of 3768) pp. 2058-2060, 2055-2057, 2054-2056