Case 1

An 8-year-old Afro-Caribbean girl with severe learning difficulties, fixed contractures of the lower limbs and immobility attends your department.

She has a 10-day history of coryza and a 7-day history of a raised, crusted rash to her face, chest and trunk. She was diagnosed with chicken pox by her GP 4 days previously.

She has not been drinking and has been vomiting in the last 24 hours.

The following observations are recorded at triage:

• Temperature = 38.5^°C
• RR = 38
• Pulse = 150
• Saturations = 90%

The child looks unwell and dehydrated. Auscultation reveals normal heart sounds with no murmur, right- and left-sided crepitations; no wheeze. Abdomen is soft and non-tender with no organomegaly.

What conditions would you include in the patient’s differential diagnosis at this early stage?

Consider the list of investigations below. Which three investigations would be of greatest benefit in seeking to refine the patient’s differential diagnosis at this stage?

Select one or more options.