hyperlipoproteinemia type 1; familial hyperchylomicronemia

Etiology

• primary or familial (see types 1a & 1b)
• secondary forms (transient)
  • acute pancreatitis
  • uncontrolled diabetes mellitus
  • hypothyroidism
  • dysglobulinemia
  • systemic lupus erythematosus
  • oral contraceptives

Epidemiology

• extremely uncommon
• familial forms diagnosed < 10 years of age
• secondary forms in adults

Pathology

• deficiency in lipoprotein lipase, or
• deficiency in apolipoprotein C2
• increased plasma chylomicrons

Genetics

• recessve form associated with defect in lipoprotein lipase
• associated with defects in USF1

Clinical manifestations

• recurrent abdominal pain
• hepatosplenomegaly
• eruptive xanthomas
• lipemia retinalis
• acute pancreatitis
• peritonitis
• manifests in childhood

Laboratory

• examination of the specimen for a creamy layer (evidence of chylomicrons)
• fasting lipid panel -> increased triglycerides (chylomicrons)
• serum amylase
  • may be falsely normal due to an unidentified inhibitory factor
  • dilution of the serum with normal saline may increase amylase levels

Management

• major objective is to prevent recurrent abdominal episodes
• strict adherence to diet
  • total fat < 0.5. mg/kg/day
  • medium-chain triglycerides that enter portal venous system directly without formation of chylomicrons may be used if adequate calories is an issue
• acute abdominal attack
  • intravenous therapy for 1st 24 hours
  • totally fat-free diet until resolution

More general terms

• hyperlipoproteinemia (HLP)
• lipid metabolism, inborn error; lipid storage disease; lipidosis

More specific terms

• hyperlipoproteinemia type 1A
• hyperlipoproteinemia type 1B

Additional terms

• acute pancreatitis
• apolipoprotein C2; apo-CII (APOC2, APC2)
• chylomicron
• diabetes mellitus
• eruptive xanthoma; eruptive xanthelasma
• hypothyroidism
• lipoprotein lipase (lipase-D, post heparin lipase, LPL, LIPD)
• oral contraceptive (OC)
• systemic lupus erythematosus