Comparison of three methods to estimate steatorrhoea

Faecal fat excretion was estimated in 24 patients using three methods. Quantitative estimations of fat excretion were calculated from both a three day faecal fat collection and a twenty-four hour faecal collection corrected for excretion of a cuprous thiocyanate marker. Breath 14CO2 excretion was measured after ingestion of a liquid meal containing 2.5 microCi of 14C-triolein in an arachis oil emulsion. Peak concentrations of 14CO2 in breath were used as an estimate of the degree of fat absorption. Correlation between the two quantitative measures of faecal fat was good (r = 0.87), 17 patients having steatorrhoea of more than 7 g fat per day by both estimations. Results of the breath test were disappointing. With the standard meal containing 20 g arachis oil the lowest peak 14CO2 excretion rate seen in subjects without steatorrhoea, 3 percent of the dose per hour, was taken as the lower limit of normal. Seven subjects with steatorrhoea as shown by faecal collections excreted normal amounts of 14CO2. When the size of the fat meal was increased to 1.0 g arachis oil per kg body weight in 16 of the subjects previously studied, all patients with proven steatorrhoea excreted less than 3 percent of the dose per hour but three of the subjects without steatorrhoea gave abnormal breath excretion results. It is concluded that the collection of a 24 hour faecal specimen using a cuprous thiocyanate marker provides a more reliable estimate of faecal fat excretion than the 14C-triolein breath test.