Estimation of ¹⁴C-triolein assimilation from postprandial serum radioactivity of ¹⁴C

Abstract

In an attempt to establish a test of lipid assimilation, based on the measurement of the postprandial serum radioactivity of ¹⁴C from ingested ¹⁴C-triolein, the activity of ¹⁴C was measured in serum samples, drawn 1,2,3,4,6 and 9 h after ingestion in 48 consecutive patients suspected of malassimilation. Simultaneously, faecal excretion of ¹⁴C was measured to estimate ¹⁴C-triolein assimilation (F-¹⁴C-Ass). F-¹⁴C-Ass served as reference of ¹⁴C-triolein assimilation. The sum of the 2- and 4-h serum concentration of ¹⁴C (S-(2+4)¹⁴C) was found to be most useful as an estimate of ¹⁴C-triolein assimilation, with regard to both the diagnostic value and applicability.

At a level of 1.0% of dose/l serum, S-(2+4)¹⁴C correctly discriminated between normal and reduced ¹⁴C-triolein assimilation in 83% of the patients (95% confidence limits 70–93%). A significant correlation between ¹⁴C-triolein assimilation and S-(2+4)¹⁴C was found (r = 0.91, P<0.001).

Since ¹⁴C-triolein assimilation correlates closely with the assimilation of dietary lipids, S-(2+4)¹⁴C seems to provide in a simple way sufficient information about lipid assimilation to be useful as a clinical test.

Key Words:

• ¹⁴C-triolein
• diagnosis
• malabsorption
• serum radioactivity