Poisoning as maltreatment — branching viva

Opening

Examiner: A two-year-old girl is on the ward for the third time with drowsiness and a seizure. Each episode has happened only at home and resolved within hours of admission. The sodium this time is 168 mmol/L with a paired urine osmolality of 320. Her mother is calm, attentive, and pressing for a central line. How do you frame this? [1] [3]

Candidate: I would treat this as a critically unwell child from acute hypernatraemia and as suspected poisoning as maltreatment in parallel. I would resuscitate the airway, breathing and circulation, control the seizures, and correct the sodium cautiously, while drawing toxicology samples before fluids obscure the picture. The recurrent bizarre toxidrome that happens only at home, remits on admission, and now shows severe unexplained hypernatraemia with inappropriately dilute urine raises Rosenberg's syndrome immediately, so I would involve my consultant and the named safeguarding lead from the first hour and not discharge the child. [3] [6]

Branch 1 — the diagnosis

Examiner: What defines this syndrome? [1]

Candidate: Rosenberg's triad: the illness 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. All three are met here — the episodes follow the suspected caregiver, they remit on admission, and the exhaustive workup has found no organic cause. The severe hypernatraemia with dilute urine is Meadow's named archetype of non-accidental salt poisoning. [1] [3]

Examiner (probe): So how do you distinguish this from a genuine metabolic disease? [6]

Candidate: I hold both possibilities in parallel rather than choosing one. The discriminating evidence is the multi-agency pattern — the chronology that shows symptoms track one caregiver and resolve on separation — plus the paired biochemistry and the documented exclusion of metabolic disease. Over-calling induction in a child with a genuine rare disease, or under-calling it in a child being poisoned, are the two mirror-image errors. [6]

Branch 2 — the workup

Examiner: Walk me through the investigation plan. [3]

Candidate: Toxicology first, sampled before treatment masks the picture — comprehensive blood and urine screen, paired serum and urine sodium and osmolality for salt, with frozen residual serum and urine saved for later agent-specific assays and a hair sample for chronic exposure. In parallel, I run the metabolic, endocrine, neurological and infectious workup so that the exclusion of genuine disease is documented, not assumed. [3] [7]

Examiner (probe): If this were recurrent hypoglycaemia, what paired test would you want? [6]

Candidate: A paired insulin and C-peptide during a hypoglycaemic episode. A high insulin with a suppressed C-peptide indicates exogenous administration, because endogenous insulin drives C-peptide in parallel — that pattern rules out an insulinoma and points to injected insulin. [6]

Branch 3 — securing the child and the separation test

Examiner: She is stable now. Her mother wants to take her home. What do you say? [4]

Candidate: I would not discharge her. The single most dangerous action at this stage is to send the child home to the suspected perpetrator while the diagnosis is unresolved, because the agent will be re-administered. I would admit her, separate her from the suspected caregiver under a documented safeguarding plan, and observe the separation response — the resolution of the toxidrome without the caregiver present is both the protection and the confirmation. [4] [6]

Examiner (probe): When is covert video surveillance indicated? [5]

Candidate: Only in a minority of cases where the suspicion is high but the evidence is incomplete, and only when it is arranged by the safeguarding team with hospital legal services and the police within the local legal framework. It is a confirmation tool, not a fishing expedition, and the decision and its rationale are documented. [5] [6]

Branch 4 — safeguarding, siblings and prognosis

Examiner: She has an infant brother at home. What is your duty to him? [4]

Candidate: Assess and protect him through the child-protection team, because the Davis data show that the recurrence and mortality risk of induced illness extends to siblings. I would make the mandatory notification, convene the multi-agency strategy meeting, and screen the sibling for occult induction — history, examination, and toxicology as indicated — before any further harm occurs. [4]

Examiner (final corner): What is the long-term outlook? [2] [5]

Candidate: Guarded, and determined by how early the induction is recognised and stopped. Children removed early from the toxic stimulus can recover, but chronic induction leaves death, brain injury, developmental disability and severe attachment disturbance, and the harm extends across siblings. Re-abuse is common, so the file is never closed on a single intervention — the disposition is a closed-loop, multi-agency plan with a named clinical lead and ongoing monitoring for recurrence. [2] [5]