Individual serum bile acid concentrations in normo- and hyperlipoproteinemia as determined by mass fragmentography: relation to bile acid pool size.

Combined gas-liquid chromatography-mass spectrometry with specific ion monitoring (mass fragmentography) has been used for assay of cholic acic (C), chenodeoxycholic acid (CD), and deoxycholic acid (D) in human serum. Deuterium-labeled C and D were used as internal standards. The relative standard deviation of duplicate samples was 3, 4, and 7% for C, CD, and D, respectively. The variation within the same individual in the fasting state was small, while the day-to-day variation was greater, especially for the dihydroxy bile acids. In normal control subjects (n = 24), the fasting serum concentration of C averaged 184 +/- 24 ng/ml (mean +/- SEM), and that of CD and D 526 +/- 62 and 407 +/- 44 ng/ml, respectively. Patients with type IIa hyperlipoproteinemia (n = 32) displayed low values of serum bile acids, with a C concentration of 121 +/- 11 ng/ml (P less than 0.01 vs. controls). A similar pattern was seen in patients with a type IIb lipoprotein pattern (n = 10). Subjects with type IV hyperlipoproteinemia (n = 32) showed serum bile acid levels within the normal limits. No relationship to age, sex, or body weight was seen in any of the patient subgroups. Bile acid kinetics were determined with an isotope dilution technique using 14C-labeled C and CD under steady state conditions in control subjects and patients with type IIa and type IV hyperlipoproteinemia. The serum concentration of C correlated significantly to its pool size in control subjects and in patients with type IIa hyperlipoproteinemia but not in patients with type IV. The serum level of CD was not related to CD pool size in any of the subgroups. The data obtained are discussed in relation to present concepts of the enterohepatic circulation. It is suggested that the intestinal content of C in the fasting state is proportional to the total C pool size. The possibility of a defective intestinal uptake of C in some patients with type IV hyperlipoproteinemia is raised.