Estimation of lipid assimilation from faecal samples using 14C-triolein as tracer and 51CrCl3 as non-absorbable marker.

14C-triolein was investigated as tracer of dietary lipids from faecal measurements in 48 consecutive gastrointestinal patients. Simultaneously, 51CrCl3 was investigated as non-absorbable marker. Faecal 51Cr was measured in a whole-body scintillation counter and faecal 14C by means of a combustion technique. This technique permitted accurate measurement of faecal 51Cr and faecal 14C in each stool collected over a 6-day period. The investigation showed that the transit time of 51Cr was slightly shorter than the transit time of 14C-triolein in patients with high faecal excretion of 14C. Nevertheless, total faecal 14C, estimated from the ratio between 14C and 51Cr in two stools, correlated very closely with measured, cumulative faecal 14C (r = 0.99, P less than 0.001). 51CrCl3 was therefore considered useful as a non-absorbable marker. The 14C-labelling of triolein was stable during gastrointestinal transit. Qualitatively, estimated faecal 14C agreed with faecal fat diagnosing steatorrhoea in 97% (95% confidence limits 90-100%) of the patients with quantitative faecal collections. Quantitatively, a significant correlation with faecal fat was found (r = 0.82, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)