Lipid disorders and familial hypercholesterolaemia — structured clinical encounter

Station brief (candidate)

You are the paediatric registrar. A well 9-year-old boy is referred after a school-entry lipid panel shows an LDL-C of 6.2 mmol per litre with a normal triglyceride and HDL. His father had a myocardial infarction at 48. The team asks you to make the diagnosis, arrange the investigations, build the management plan, and speak with the family. You have 12 minutes with the team and 5 minutes for examiner discussion. [5]

Information available on request

• Well 9-year-old boy, asymptomatic, normal examination, no xanthomas, no arcus. [2]
• Lipid panel: LDL-C 6.2 mmol per litre, triglyceride normal, HDL normal, non-HDL-C raised. [2]
• Father: myocardial infarction at 48; paternal uncle: coronary bypass at 52. [5]
• Parents are anxious and ask whether this is inherited and whether the other children need testing. [1]

Tasks

1. State the most likely diagnosis and the bedside and biochemical features that support it. [2]
2. Outline the investigation bundle, including the secondary-cause screen and the genetic test, and explain why the secondary screen precedes the genetic label. [2]
3. Describe the management plan, naming the first-line drug, the age to start it, the target, and the safety evidence in children. [4]
4. Communicate the inheritance, the cascade-screening plan, and the prognosis to the parents in plain language. [1]

Marking anchors

Must-hit

• Diagnoses heterozygous familial hypercholesterolaemia: the untreated LDL-C at 6.2 mmol per litre is well above the 5.0 mmol per litre threshold, the triglyceride is normal, and the first-degree family history of premature cardiovascular disease is present. [2]
• Sends a repeat lipid profile with lipoprotein(a), a secondary-cause screen (thyroid-stimulating hormone, renal function and urinalysis, liver function) to exclude hypothyroidism, nephrotic syndrome, cholestasis and a drug, and genetic testing of LDLR, APOB and PCSK9 — because a secondary cause must be treated or excluded before committing to the inherited label. [2]
• Plans lifestyle plus a statin started at the lowest licensed dose from age 8 to 10 years and titrated to an LDL-C target ideally below 3.1 mmol per litre, citing the safety evidence that childhood statin normalised carotid intima-media thickness with no twenty-year safety penalty. [4] [6]

Merit

• Explains that FH is autosomal dominant, so each first-degree relative has a one in two chance of carrying the variant, and arranges cascade testing of both parents and all siblings once the index variant is confirmed. [1]
• Counsels the parents in plain language: the condition is inherited and treatable, the other children need testing, and the boy can expect a near-normal life expectancy with early and sustained treatment. [1]
• Places the case in context: FH is underdiagnosed and under-treated because the child is asymptomatic, so a family history of premature cardiovascular disease is the flag that should always trigger a lipid profile in the child. [2]

Fail

• Reassures the family that the cholesterol is diet-related and defers the work-up, while the atherosclerotic deposit accumulates. [2]
• Labels the child with FH and starts a statin without excluding a secondary cause or confirming genetically. [2]
• Treats only the index child and omits cascade screening of the parents and siblings. [1]