Endocrine and diabetes medicines — branching viva

Station map

Branch A — Diabetic ketoacidosis: insulin and fluids

Examiner: A 7-year-old presents drowsy with Kussmaul breathing, bedside glucose 24 mmol per L, ketones 6.2 mmol per L and venous pH 7.08. She is 7 percent dehydrated but not in shock. Talk me through your insulin and fluid prescribing. ^[4]

Strong answer should include:

• Restore intravascular volume first with isotonic saline; a 10 to 20 mL per kg bolus only if shocked, otherwise calculated deficit replacement over 24 to 48 hours. ^[4]
• Start the continuous intravenous insulin infusion at 0.05 to 0.1 unit per kg per hour only after volume is restored. ^[4]
• Never give an intravenous insulin bolus in paediatric DKA, because the steep osmolar fall contributes to cerebral oedema. ^{[4] [9]}
• Replace potassium once insulin starts and urine output is established; add dextrose when glucose falls to around 11 to 14 mmol per L. ^[4]
• Transition to subcutaneous insulin only when ketones clear, the pH normalises, and the child is eating.

Examiner probe: Why is insulin, not fluids or bicarbonate, the definitive treatment? ^[4]

Strong answer should include:

• DKA is an insulin-deficient ketotic state; insulin restores glucose uptake and switches off lipolysis and ketogenesis. ^[4]
• Fluids restore volume but do not stop ketogenesis; bicarbonate is avoided because it does not improve outcome and may worsen cerebral acidosis. ^[9]

Branch B — Neonatal levothyroxine