Endocrine emergencies: integrated approach — formative SAQs

SAQ 1 — The young child with new-onset DKA (20 marks, ~15 minutes)

A 4-year-old girl has had two weeks of polyuria, polydipsia and a 3 kg weight loss attributed to a virus. She now presents vomiting, with deep sighing breathing. Bedside glucose is 28 mmol/L, venous pH 7.08, bicarbonate 8 mmol/L and beta-hydroxybutyrate 5.2 mmol/L. She is volume depleted but not in shock. She is drowsy but rousable. ^[1]

Questions

1. Give the diagnosis, the three biochemical criteria you used, and the severity grade. (5 marks) ^[1]
2. Outline the first-hour fluid, insulin and potassium plan, and state one thing that must not be done with insulin. (6 marks) ^[1]
3. Four hours into treatment she develops a new headache, becomes more lethargic and her heart rate slows, unrelated to sleep. Give the diagnosis and the immediate management. (5 marks) ^[1]
4. She is now eating. How do you move her from intravenous to subcutaneous insulin? (4 marks) ^[1]

Model answer (must-hit)

1. This is DKA. ISPAD requires all three criteria: glucose above 11 mmol/L, venous pH below 7.3 or bicarbonate below 18 mmol/L, and ketonaemia or ketonuria. ISPAD categorizes the severity of DKA by the degree of acidosis. A pH below 7.1 or bicarbonate below 5 mmol/L grades DKA as severe, and a pH below 7.2 or bicarbonate below 10 mmol/L as moderate. Her pH of 7.08 is below 7.1, so she has severe DKA. ^[1]

2. Fluid replacement begins before insulin. Give 0.9% saline 10 to 20 mL/kg over 20 to 30 minutes, then replace the deficit over 24 to 48 hours with maintenance fluids. Start insulin at 0.05 to 0.1 U/kg/h at least 1 hour after fluids begin. Begin potassium at 40 mmol/L, but defer it until urine output is documented if potassium is above 5.5 mmol/L. Do not give an IV insulin bolus: it is unnecessary, can precipitate shock and can worsen hypokalaemia. ^[1]

3. New headache, lethargy and slowing of the heart rate not related to sleep are ISPAD warning signs of cerebral injury. Start treatment as soon as it is suspected. Give mannitol 0.5 to 1 g/kg IV over 10 to 15 minutes, or 3% hypertonic saline 2.5 to 5 mL/kg over 10 to 15 minutes. Adjust the fluid rate to keep a normal blood pressure while avoiding excess fluid. Intubation may be needed for impending respiratory failure from severe neurological compromise. ^[1]

4. Give the first subcutaneous injection of rapid-acting insulin 15 to 30 minutes before stopping the infusion, to prevent rebound hyperglycaemia. With long-acting insulin, the overlap should be longer. The most convenient time to change is just before a meal. ^[1]