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Familial chylomicronemia syndrome (FCS): Suspect-and-test checklist for clinicians

A one-page worksheet that turns the full Familial chylomicronemia syndrome (FCS) diagnosis guide into something you can use at the point of care: what to look for, what to order, which results should not end the workup, and who else to test or refer.

Who it is forClinicians and care teams who may see Familial chylomicronemia syndrome (FCS) before it is diagnosed, including primary care, the specialists named in the guide, and referral or genetics coordinators.
When to use itWhen Familial chylomicronemia syndrome (FCS) is on the differential, when a patient has several red flags, or when you are preparing a referral or a second opinion.

How to use it, section by section

  1. Red flags present: Tick each finding the patient has. They are grouped by body system so you can scan quickly.
  2. Already labeled as: Tick earlier diagnoses on the chart that the sources say are often given first.
  3. Family to test: Note relatives who may need testing, and record when symptoms began and which specialists have already been seen.
  4. Testing, in order: Tick each test as you order it and write the result on its line. The order follows the published sources.
  5. Results that do not rule it out: A reminder of findings that can look reassuring but do not exclude Familial chylomicronemia syndrome (FCS).
  6. Specialists: Tick the referral, then write who it went to and any notes.
Two ways to fill it inPrint it blank and write on it, or tick boxes and type on this screen first, then print or save as a PDF. Keep it with the chart or send it with the referral.
PrivacyNothing you type is sent or saved. It stays in this browser tab and disappears when you close it. Use patient initials, not full identifiers.

What it is not: Not a diagnostic score, a protocol or coding advice. It summarizes published sources, and clinical judgment and the treating clinician govern. Every point is sourced in the full Familial chylomicronemia syndrome (FCS) guide.

One Letter page. Use your browser's print or save as PDF.Full guide with sources
Suspect-and-test checklist
Familial chylomicronemia syndrome (FCS)

Autosomal recessive loss of lipoprotein lipase function. Start from triglycerides that stay above 885mg/dL with no secondary cause.

ICD-10-CME78.3Trial Friend for Clinicians

1Red flags present

Triglycerides and the sample

Pancreas and abdomen

Skin, eyes, liver and spleen

Age and life stage

Family and ancestry

2Already labeled as

3Family to test

4Testing, in the order the sources describe

  1. Repeat fasting triglyceridesPersistent chylomicronemia: 1000mg/dL or more in more than half of measurements (NLA and ASPC).
    Result
  2. Secondary factorsDiabetes, obesity, ethanol, hypothyroidism, nephrotic syndrome, pregnancy, estrogens, steroids, retinoids and other drugs.
    Result
  3. Response to fibrates or omega-3Very little or none in FCS; modest to substantial in MCS.
    Result
  4. LDL cholesterol, apolipoprotein B, BMI and pancreatitis historyUltracentrifuge LDL cholesterol under 39.2mg/dL, BMI under 26.1kg/m2 and pancreatitis history, at least 2 of 3: 91.0% accuracy (Akcea and Ionis funded analysis).
    Result
  5. European FCS score (Moulin 2018)At 10 or more: 88% sensitivity, 85% specificity when published; 74.3% to 96% sensitivity since. Akcea-paid medical writing in companion paper.
    Result
  6. North American FCS score (Hegele 2025)Score of 45 or more very likely, 60 or more definite. Funding not stated in the abstract.
    Result
  7. Gene testing: LPL, APOC2, APOA5, GPIHBP1, LMF1Biallelic pathogenic or likely pathogenic variants confirm. LPL sequencing finds about 96%, deletion/duplication about 4%.
    Result
  8. Post-heparin LPL activityFor negative or inconclusive gene results (Delphi panel). Selected specialist centers only.
    Result
  9. GPIHBP1 or LPL autoantibodiesDelphi panel lists intermittent levels, another autoimmune condition, adult onset and inconclusive genetics as reasons to reconsider autoimmune chylomicronemia (it names anti-GPIHBP1 antibodies).
    Result

5Results the sources say do not rule it out

  • A triglyceride level under 1000mg/dL on one occasion. Balance trial range in confirmed FCS: 334 to 6898mg/dL.
  • A negative gene test. Nearly 25% with a clinical picture of FCS test negative (Delphi panel).
  • Sequencing without deletion/duplication analysis.
  • A score under the cut-off. Sensitivity was 74.3% in the Montreal validation.
  • No family history. Inheritance is recessive.
  • Overweight or diabetes. In the UK registry, 26% of patients with FCS had diabetes.
  • A variant of uncertain significance. It neither establishes nor rules out the diagnosis.

6Specialists the sources name

Diagnosis code: E78.3 HyperchylomicronemiaCodes patients often carry before diagnosis are listed in the online guide.
Full guide and sourcesEvery point here is sourced in the online guide, which also has a patient note to print.
Trial Friend, trialfriend.com/for-clinicians. Key sources: GeneReviews (2026); NLA expert clinical review (2025); NLA and ASPC consensus (2025); Moulin 2018 FCS score; Hegele 2025 North American FCS score; Bashir 2024 UK score validation; all 32 with links in the online guide. Checked November 13, 2026. A reference checklist for licensed clinicians that summarizes published sources. It is not a diagnostic tool, a score or a protocol, and it does not replace clinical judgment, local practice or the prescribing information. Not coding advice. Trial Friend never receives anything written or typed on this sheet.