PLASMA LATHOSTEROL AS A SCREENING-TEST FOR BILE-ACID MALABSORPTION DUE TO ILEAL RESECTION - CORRELATION WITH (75)SEHCAT TEST AND FECAL BILE-ACID EXCRETION

1. Plasma lathosterol concentration, known to reflect cholesterol and bile acid synthesis, was evaluated as a screening test for bile acid m alabsorption, comparing it with faecal bile acid measurements, SeHCAT test and Schilling test in 22 subjects of whom six were healthy contro ls and 16 had Crohn's disease with ileal resections of varying length, 2. Plasma lathosterols and other non-cholesterol sterols were determi ned by GLC, Faecal bile acids were measured by GLC, and SeHCAT retenti on times by gamma camera, The study subjects were divided into two gro ups according to the degree of bile acid malabsorption: controls (faec al 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 bi ological half-life of (75)SeHCAT (T1/2) was 95.6+/-16.3h and 14.1+/-4. 1 h, respectively, Plasma lathosterol levels were significantly elevat ed in patients with bile acid malabsorption (742+/-84 mu g/ml compared with 400+/-59 mu g/ml in control subjects) and correlated closely wit h faecal bile acid levels (r = 0.779, P < 0.001), with (75)SeHCAT 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)-cholesterol with faecal bile acids (r = 0.784, P < 0.001) and (75)SeHCAT (r = -0. 505, P < 0.05), The biological half-life of SeHCAT correlated with fae cal bile acid excretion (r = -0.702, P < 0.001), Using mean+2 SD of la thosterol (Ire mu g/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 dete rmination to detect bile acid malabsorption, 4. The results indicate t hat both the (75)SeHCAT test and plasma lathosterol detect bile acid m alabsorption in patients with ileal resections for Crohn's disease, Ho wever, plasma lathosterol is a simpler and less expensive method.