Alexandre V , Davila AM , Bouchoucha M , Bertin C , Even P , Lamberto C , Tome D , Benamouzig R. - 44786 N - Dig Liver Dis 2013 ; 45(9) : 727-32.
BACKGROUND: Lactose malabsorption occurs frequently and the variable consequent intolerance may seriously impair quality of life. No reliable and convenient test method is in routine clinical practice. A recent animal study showed that the respiratory quotient changed significantly after ingestion of sucrose and lactose in naturally lactase-deficient rats.
AIMS: This exploratory study evaluated the relevance of monitoring the respiratory quotient after lactose ingestion to detect malabsorption.
METHODS: Healthy volunteers were identified and classified lactose absorbers and malabsorbers by a lactose tolerance test (25g). After an overnight fast, a second lactose challenge was performed to monitor hydrogen excretion and respiratory quotient kinetics over 4h. Participants also completed questionnaires to score and localise their gastrointestinal symptoms.
RESULTS: 20 subjects were enrolled (10 per group, 60% males, mean age 34+/-4 years). Respiratory quotient kinetics were different between absorbers and malabsorbers during the first 100min after lactose ingestion (p<0.01) and during the initial 30-50min period. Respiratory quotient was significantly, positively correlated to peak glycaemia (R=0.74) and negatively correlated to hydrogen excretion (R=-0.51) and symptoms score (R=-0.46).
CONCLUSIONS: Indirect calorimetry could improve the reliability of lactose malabsorption diagnosis. Studies on larger populations are needed to confirm the validity of this test and propose a simplified measurement.