1. Plasma
lathosterol concentration, known to reflect
cholesterol and
bile acid synthesis, was evaluated as a screening test for
bile acid malabsorption, comparing it with faecal
bile acid measurements,
SeHCAT test and Schilling test in 22 subjects of whom six were healthy controls and 16 had
Crohn's disease with ileal resections of varying length. 2. Plasma lathosterols and other non-
cholesterol sterols were determined by GLC. Faecal
bile acids were measured by GLC, and
SeHCAT retention times by
gamma camera. The study subjects were divided into two groups according to the degree of
bile acid malabsorption: controls (faecal
bile acids < 10 mg day-1 kg-1, n = 9) and
bile acid malabsorption (faecal
bile acids > 10 mg day-1 kg-1, n = 13). 3. Faecal
bile acid excretion was 5.9 +/- 1.0 mg day-1 kg-1 in control subjects and 45.7 +/- 6.1 mg day-1 kg-1 in the
bile acid malabsorption group. The
biological half-life of 75SeHCAT (T1/2) was 95.6 +/- 16.3 h and 14.1 +/- 4.1 h, respectively. Plasma
lathosterol levels were significantly elevated in patients with
bile acid malabsorption (742 +/- 84 micrograms/ml compared with 400 +/- 59 micrograms/ml in control subjects) and correlated closely with faecal
bile acid levels (r = 0.779, P < 0.001), with 75SeHCAT T1/2 (r = -0.524, P < 0.05) and with Schilling test (r = -0.591, P < 0.05). Significant correlations were also obtained for delta 8-cholestenol with faecal
bile acids (r = 0.784, P < 0.001) and 75SeHCAT (r = -0.505, P < 0.05). The
biological half-life of
SeHCAT correlated with faecal
bile acid excretion (r = -0.702, P < 0.001). Using mean+2 SD of
lathosterol (In micrograms/ml
cholesterol) as a cut-off value and 10 mg day-1 kg-1 as the upper limit for faecal
bile acid excretion, the test gives 100% sensitivity and 82% specificity for plasma
lathosterol determination to detect
bile acid malabsorption. 4. The results indicate that both the 75SeHCAT test and plasma
lathosterol detect
bile acid malabsorption in patients with ileal resections for
Crohn's disease. However, plasma
lathosterol is a simpler and less expensive method.