A Triple Isotope Technique for Estimation of Fat and Vitamin B₁₂ Malabsorption in Crohn's Disease

Abstract

A test for simultaneous estimation of vitamin B₁₂ and fat absorption from stool samples was investigated in 25 patients with severe diarrhoea after operation for Crohn's disease. ⁵¹CrCl₃ was ingested as a non-absorbable marker, ⁵⁸Co-cyanocobalamin as vitamin B₁₂ tracer, and ¹⁴C-triolein as lipid tracer. Faeces were collected separately for 3 days. Some stool-to-stool variation in the ⁵⁸Co/⁵¹Cr and ¹⁴C/ ⁵¹Cr ratios was seen. When the ⁵⁸Co-B₁₂ and ¹⁴C-triolein excretion was estimated in samples of the two stools with the highest activities of ⁵¹Cr, the variations of the estimates were less than ±10% and ±15% of the doses ingested, respectively. Twelve of the 25 patients were not able to collect faeces and urine quantitatively and separately. However, in all patients faeces with sufficient radioactivity for simultaneous estimation of faecal ⁵⁸Co-B₁₂ and ¹⁴C-triolein excretion from stool samples were obtained.

Key Words:

• Carbon isotopes
• faeces analysis
• malabsorption diagnosis
• vitamin B₁₂