lethargic childA child may present with lethargy, altered mental status or drowsiness. Lethargy can be a manifestation of a number of clinical conditions , ranging from toxic and metabolic conditions to seizures. The differential diagnosis is broad and a proper workup is needed apart from a detailed history and physical examination.

Laboratory Data

Basic Metabolic Panel

Electrolyte abnormalities ( hypo/hypernatremia, hypo/hyperkalemia, hypo/hypercalcemia ) and hypo/hyperglycemia can present with alteration of mental status. Matabolic acidosis may point to an underlying metabolic disorder or intoxication. Respiratory acidosis can be seen in intoxications with alcohol, benzodiazepines and barbiturates.

Renal and Hepatic Profile

Can indicate acute or chronic end organ dysfunction.

CBC with differentials

Elevated WBC count may indicate acute infection.

Toxicology Screening and Drug levels

Based on patient’s history, order blood levels of prescription medications, ingested medications or substances of abuse.


Obtain if hypoxia or acid base problems are suggested by history or physical examination.

Lumbar puncture

Perform if history and physical exam suggests an intracranial infection ( meningitis or encephalitis ) ; can also demonstrate subarachnoid hemorrhage. Do not perform in the presence of increased intracranial pressure or a space occupying lesion because of risk of herniation.

Radiographic and Other Studies

Neuroimaging ( CT or MRI )

Obtain a neuroimaging study for all patients with altered mental status. If patient has a normal exam and only a history of altered arousal , study is not needed emergently. MRI is a more sensitive exam however sedation is often necessary because patient must remain still for a prolonged period of time.


The gold standard for seizures ; can demonstrate cerebral cortical dysfunction due to generalized encephalopathy or localized destructive or space occupying lesion.


Obtain if a cardiac disorder is suspected.

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