Poisoning as maltreatment — formative SAQs

SAQ 1 (10 marks)

A two-year-old girl is admitted for the third time in six months with drowsiness and a generalised seizure. Each episode has happened only at home, has resolved within hours of admission, and no metabolic, infectious or neurological workup has explained it. Her mother is calm, attentive, and asks whether a central line would make the repeated blood tests easier. On this admission the sodium is 168 mmol/L with a paired urine osmolality of 320 mOsm/kg. [1] [3]

1. Give your immediate clinical and safeguarding actions, and the specific samples you would draw before treatment. (4) [3]
2. State Rosenberg's defining triad and explain how this presentation meets it, naming the evidence. (3) [1]
3. Describe the stepped management plan from recognition to closed-loop follow-up, including the siblings. (3) [4]

Model answer — SAQ 1

(1) Immediate actions and sampling (4). Treat the toxidrome as genuine poisoning: stabilise the airway, breathing and circulation, control seizures, and correct the hypernatraemia cautiously to avoid cerebral oedema — but draw the toxicology samples first. Send blood and urine for a comprehensive toxicology screen, paired serum and urine sodium and osmolality to document salt induction before fluids obscure the picture, and freeze residual serum and urine for later agent-specific assays; consider a hair sample for chronic exposure. Run safeguarding from the first hour: inform the consultant and the named safeguarding lead, do not discharge the child or allow unsupervised access by the suspected caregiver, and preserve the chart chronology. [3] [6]

(2) Rosenberg's triad (3). Rosenberg defined the illness by three features: it is produced or reproduced by the caregiver, it resolves when the child is separated from that caregiver, and it is not explained by any genuine disease. This child meets all three — the bizarre recurrent hypernatraemic seizures occur only in the suspected caregiver's presence, they remit on each admission, and the exhaustive workup has excluded organic disease. The severe unexplained hypernatraemia with inappropriately dilute urine is Meadow's named archetype of non-accidental salt poisoning. [1] [3]

(3) Stepped plan and siblings (3). The pathway runs recognise, resuscitate and sample, secure and separate, confirm, report and protect, then follow up closed-loop. Admit the child, separate her from the suspected caregiver under a documented plan, observe the separation response as confirmation, complete the targeted toxicology and — if needed within the legal framework — team-led covert video surveillance. Make the mandatory child-protection notification, convene the multi-agency strategy meeting, and assess and protect the siblings, because the Davis data show the recurrence and mortality risk extends to them. [4] [6]

SAQ 2 (10 marks)

A four-year-old boy under investigation for recurrent hypoglycaemic seizures has his blood glucose fall to 1.4 mmol/L during a witnessed fast on the ward, with a simultaneous insulin of 240 pmol/L and a C-peptide below the detectable limit. His mother, a healthcare worker, has been present for each episode and asks that the team not wake the child for further tests. [6]

1. Interpret the paired insulin and C-peptide result and state what it indicates. (3) [6]
2. Outline the further toxicology and organic workup, and explain why both run in parallel. (4) [6]
3. Describe the pitfalls that would endanger this child, and how you would avoid them. (3) [4]

Model answer — SAQ 2

(1) Insulin and C-peptide interpretation (3). A high insulin with a suppressed C-peptide during hypoglycaemia indicates exogenous insulin administration: endogenous insulin secretion drives C-peptide in parallel, so a suppressed C-peptide with a high insulin is incompatible with an insulinoma or any genuine hyperinsulinaemic state and points to injected insulin. This is the discriminating test for insulin induction as a form of poisoning as maltreatment. [6]

(2) Parallel workup (4). Send blood and urine for a comprehensive toxicology screen with specific assays for insulin and oral hypoglycaemics, and freeze residual serum and urine for later analysis; re-draw any suspicious sample from a fresh, witnessed site. Run the organic differential in parallel — metabolic and endocrine testing to document the exclusion of genuine disease — because the safeguarding threshold and the clinical diagnosis both require you to show that no disease explains the picture. Investigating only the organic cause, or only the safeguarding suspicion, is the classic error. [6]

(3) Pitfalls and avoidance (3). Confronting or accusing the mother before the child is safe and the strategy agreed destroys the separation opportunity and may trigger escalation or evidence destruction; discharging the child to her while the diagnosis is unresolved guarantees re-exposure; relying on a single clinician rather than the multi-agency team compromises the case; and neglecting the siblings leaves them at risk. Avoid each by securing and separating the child first, owning the strategy through the named safeguarding lead and the multi-agency meeting, and protecting the siblings from the outset. [4] [6]