Increase of low serum concentrations of high-density lipoprotein (HDL) cholesterol in TIA-patients treated with phenytoin.

Serum high density lipoprotein (HDL) cholesterol and other lipoproteins were measured in 27 TIA-patients with a mean age of 49 +/- 10 years before and during phenytoin therapy. The pretreatment concentrations of HDL-cholesterol (mmol/l, mean +/- SD) were lower (p less than 0.001) in male (1.03 +/- 0.25) and in female patients (1.15 +/- 0.44) than in healthy male (1.28 +/- 0.34) and female controls (1.52 +/- 0.31) respectively. After one month's phenytoin therapy HDL cholesterol concentrations reached normal levels (men 1.33 +/- 0.38, women 1.61 +/- 0.27) and after 9 months of therapy even surpassed them (men 1.47 +/- 0.27, p less than 0.05; women 1.91 +/- 0.33, p less than 0.01). Percent increase of HDL cholesterol after 9 months of therapy was 42 +/- 25 in men and 68 +/- 46 in women. There was a positive correlation (r = 0.43, p less than 0.05) between serum phenytoin level and increase of HDL cholesterol. HDL/LDL cholesterol ratio increased (p less than 0.01) also during 9 months of therapy (men from 0.26 +/- 0.05 to 0.36 +/- 0.10, women from 0.26 +/- 0.07 to 0.43 +/- 0.13) and showed a positive correlation (r = 0.91, p less than 0.001) with increase of serum HDL cholesterol. The HDL cholesterol levels achieved have been maintained with a mean serum phenytoin level of 5.6 +/- 3.6 mg/l. Phenytoin induced increase in serum HDL levels should not yet be equated with protection against atherosclerosis.