Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (70 page)

   Familial combined hyperlipidemia occurs in 0.5% of general population and 15% of survivors of AMI <60 years old. Premature CAD occurs later in life (after age 30 years) than with familial hypercholesterolemia.

   Xanthomas are rare. Patients are often overweight.

   Laboratory Findings

   There may be any combination of increased LDL-C and VLDL and chylomicrons; HDL-C is often low.

   Different family members may have increased serum TC or TG or both.

FAMILIAL DYSBETALIPOPROTEINEMIA (TYPE III)

   Definition

   Familial dysbetalipoproteinemia occurs in 1 per 5,000–10,000 persons.

   Atherosclerosis is more common in peripheral than coronary arteries. Tuberous and tendinous xanthomas and palmar and plantar xanthomatous streaks are present.

   Laboratory Findings

   Diagnosis by combination of ultracentrifugation and isoelectric focusing that shows abnormal apoprotein E pattern.

   Abnormality of apoprotein E with excess of abnormal lipoprotein (beta mobility—VLDL); TC > 300 mg/dL plus TG > 400 mg/dL should suggest this diagnosis.

   VLDL cholesterol-to-TG ratio = 0.3 (normal ratio = 0.2).

   Familial Hypertriglyceridemia (Type IV)