Hypocholesterolemia in hairy cell leukemia: a marker for proliferative activity

Hypocholesterolemia is a well-documented phenomenon associated with a variety of hematological malignancies and nonmalignant disorders associated with splenomegaly. To determine the incidence of hypocholesterolemia in patients with hairy cell leukemia (HCL), we measured the serum cholesterol levels before and after a single cycle of 2-chlorodeoxyadenosine (2-CdA) in 46 patients. The mean pre-treatment serum cholesterol level was 152.8 mg/dl (range, 60 to 293 mg/dl). The mean post-treatment serum cholesterol level was 190.0 mg/dl. This was significantly higher than the pre-treatment values (P <0.0001). Twelve patients who had previously undergone splenectomy showed a similar response to treatment, with a pre-treatment value of 180.0 mg/dl and a post-treatment value of 219.8 mg/dl (P < 0.0001). However, there was a significant difference in the pre-treatment serum cholesterol levels in the nonsplenectomized patients (143.0 mg/dl) compared to the splenectomized patients (180.0 mg/dl) (P < 0.03). The pre-treatment serum cholesterol did not correlate with the pre-treatment splenic index (correlation coefficient = -0.39, P < 0.065). Similarly, there was no correlation between the change in splenic index and the change in serum cholesterol level post-treatment. These findings suggest that hypocholesterolemia in HCL is related to tumor burden and not to splenomegaly alone. Since cholesterol is critical to hairy cell metabolism and structure, treatment strategies interfering with cholesterol synthesis may be productive.