The Significance of Initiating Further Tests for Children Presenting with Lethargy


This article discusses the importance of requesting further tests and observations for children presenting with a background of fever, vomiting and persistent lethargy.

A Case Example

Patient presented to the Emergency Department with a background of fever, vomiting and lethargy. After administering fluids, vomiting and fever ceased, however the patient was still lethargic and showed abnormal vitals. Patient was discharged after tests showed no infection and advised to continue consuming fluids. Later that evening, the patient continued showing signs of lethargy, lost consciousness and sadly died.

Independent Recommendations to Improve Healthcare Standards and Patient Safety

When children present with these red flag symptoms, the first thought is usually viral illness, which needs to be ruled out. If a child has abnormal vital signs, but has ceased vomiting, is retaining fluids and passing urine without issue, further observations should be taken, especially in light of continued lethargy.

Clinicians should bear in mind the importance of further testing and observations, especially if a diagnosis cannot be made and they are still showing symptoms of fatigue.

In light of the above case, where the child sadly passed away, the importance of thorough investigations and taking into account the parent’s anxieties cannot be underestimated. If the child’s vitals are still abnormal, then further tests should ensue, which should include but are not limited to:

  1. Blood Gases This could reveal if the child is acidotic, where fluid bolus and antibiotics can then be administered.

  2. Full Blood Count By revealing the red cell, white cell and platelet counts, the cause of the lethargy will have a greater chance of being identified, along with other potential issues.

  3. Renal Function and Electrolyte Tests As lethargy in children should be treated as a serious symptom, renal and electrolyte tests can show underlying causes of infection or disease which may not reveal themselves during basic testing in the Emergency Department.

  4. Chest X-Ray Inflamed muscle tissue can cause fatigue and when tachycardia is present, in line with other symptoms such as vomiting and tachypnoea, a chest x-ray can show potential diagnoses such as myocarditis or fluid on the lungs.

  5. Blood Cultures Lethargy alongside periods of vomiting and fever should be taken seriously until a diagnosis is made. Blood cultures can reveal infections or diseases present in a child’s blood and should be requested in line with the above when the diagnosis is uncertain. For example, Kawasaki disease can be missed if thorough investigations are not completed and can lead to unfortunate outcomes.

These tests can further reveal the cause of the lethargy, especially when the child has abnormal vital signs. By following these additional tests and observations, there is a higher probability that a differential diagnosis can be made, and a care pathway can then be implemented.


When a child presents with signs of continued lethargy with periods of vomiting and fever, even if the latter two cease, the patient should be referred for further testing and observations in line with the above, to rule out serious diagnoses such as myocarditis and Kawasaki Disease (also known as mucocutaneous lymph node syndrome – mainly affecting children under 5). Lethargy in children should be seen as an emergency and the patient should not be discharged without the cause of this being fully investigated.

By raising awareness of the above issues, THEMIS aims to assist in developing awareness of initiating further tests when children present with prolonged lethargy, therefore improving clinical care and reducing litigation risk.