Diagnosing FCS
Diagnostic scoring tools for familial chylomicronemia syndrome (FCS)
Refining the diagnostic process for FCS
In 2018, a panel of European experts (Moulin et al) published an algorithm-based tool to help identify FCS, which has been aiding clinicians for years.6 In 2024, the North American FCS (NAFCS) criteria published by Hegele et al were developed and validated specifically for patients in the United States and Canada.7 These tools use key clinical features of FCS to generate a score that can help facilitate a diagnosis of FCS.6,7
This information is intended as educational information for healthcare professionals. It does not replace a healthcare professional’s judgment or clinical diagnosis.
This information is intended as educational information for healthcare professionals. It does not replace a healthcare professional’s judgment or clinical diagnosis.
Using the NAFCS scoring criteria to confer a clinical diagnosis7
This calculator, adapted from Hegele et al, should be used in patients ≥1 year old with hypertriglyceridemia (≥440 mg/dL). In patients ≥10 years old, the calculator is intended for patients who are not responsive to fibrates and high-dose omega-3 fatty acids even when the patient is adherent to therapy (ie, triglycerides do not decrease by 20% or more from these treatments and do not remain reduced).7
Current age (years)
Body mass index (percentile for children/adolescents)
History of pancreatitis
Presence of secondary factors that may contribute to hypertriglyceridemia‡
Laboratory values (select if true)
Additional points added:
Interpreting results
- ≥60 strongly indicates definite FCS
- ≥45 suggests likely FCS rather than MCS
- ≥30-44 suggests patient may have FCS and genetic testing should be considered§
- <30 deemed unlikely to be FCS, but genetic testing may still be needed
*The NAFCS Score does not provide a value for pregnant patients.7 †Calculator cannot be used for patients <1 year old. If infant presents with no secondary factors that may contribute to hypertriglyceridemia, consider a diagnosis of FCS. If infant presents with ≥1 secondary factor that may contribute to hypertriglyceridemia, but with 2 triglyceride readings >880 mg/dL and unexplained failure to thrive, consider a diagnosis of FCS.7 ‡See the table below for secondary factors that may contribute to hypertriglyceridemia.19 §Further research is needed to determine the validity of a score from 30-44.7 BMI=body mass index; MCS=multifactorial chylomicronemia syndrome.
Using the Moulin et al scoring criteria to confer a clinical diagnosis6
Use the scoring tool below to assess your patient for familial chylomicronemia syndrome (FCS). Select each item that applies to determine your patient's FCS score. The numbers in brackets represent the weighting given to the presence of each characteristic.6
Triglycerides
Fasting triglycerides >880 mg/dL for 3 consecutive blood analyses* [+5]
Fasting triglycerides >1770 mg/dL at least once [+1]
Previous triglycerides <177 mg/dL at least once [-5]
Medical history
No secondary factor† (except pregnancy‡ and ethinylestradiol) [+2]
History of pancreatitis [+1]
Unexplained recurrent abdominal pain [+1]
No history of familial combined hyperlipidemia [+1]
No response (triglyceride decrease <20%) to hypolipidemic treatment [+1]
Onset of symptoms at age:
<40 years [+1]
<20 years [+2]
<10 years [+3]
Onset of symptoms at age:
- ≥10: FCS very likely
- ≤9: FCS unlikely
- ≤8: FCS very unlikely
Adapted from Moulin et al. Identification and diagnosis of patients with familial chylomicronaemia syndrome (FCS): expert panel recommendations and proposal of an "FCS score". Atherosclerosis. 2018;275:265-272.
*Plasma triglyceride concentration measured at least 1 month apart. Eruptive xanthomas may be used as a surrogate for high triglyceride levels (rare).6
†Secondary factors include alcohol, diabetes, metabolic syndrome, hypothyroidism, corticosteroids, and additional drugs. See table below for secondary factors that may contribute to hypertriglyceridemia.6
‡If diagnosis is made during pregnancy, a second assessment is necessary to confirm diagnosis post partum.6