Hyperviscosity syndrome in a hypercholesterolemic patient with primary biliary cirrhosis

A 45-yr-old woman with primary biliary cirrhosis, xanthomatosis, and marked hypercholesterolemia developed symptoms of the hyperviscosity syndrome on three separate occasions. On presentation, she had a plasma total cholesterol concentration of 53.40 mM (2065 mg/dl) and a relative serum viscosity of 2.9. Following three courses of plasma exchange in a 5-day period, the total cholesterol level decreased to 6.75 mM (261 mg/dl) and the viscosity to 1.3. The cutaneous xanthomata were markedly diminished 1 wk following plasma exchange. Despite therapy with colestipol (30 g/d), the hyperviscosity syndrome developed 147 days later. This cycle recurred again 137 days after colestipol was discontinued. Serum viscosity and total cholesterol concentration were highly correlated during the postexchange or accumulation phases (R = 0.95, 95% CI: 0.85, 0.98) and during the exchange or interventional phases (R = 0.95, 95% CI: 0.84, 0.99). Serum viscosity was less significantly correlated with total serum protein (R = 0.84; 95% CI: 0.55, 0.95) or with plasma triglyceride (R = 0.63; 95% CI: 0.26, 0.81). There were no significant correlations of red cell mass, plasma fibrinogen levels, or serum bile salts with viscosity. Subfractionation of plasma into lipoprotein classes showed 45% of total cholesterol in the lipoprotein X fraction and a presumptive slow alpha-lipoprotein species. It is postulated that both the hyperviscosity syndrome and rapid resolution of xanthomata in the patient may be attributable to the physiology of her abnormal lipoprotein particles.