How to interpret hydrogen breath tests

Abstract

Hydrogen breath tests using various substrates like glucose, lactulose, lactose and fructose are being used more and more to diagnose small intestinal bacterial overgrowth (SIBO) and lactose or fructose malabsorption. Though quantitative culture of jejunal aspirate is considered as gold standard for the diagnosis of SIBO, hydrogen breath tests, in spite of their low sensitivity, are popular for their non-invasiveness. Glucose hydrogen breath test is more acceptable for the diagnosis of SIBO as conventionally accepted double-peak criterion on lactulose hydrogen breath test is very insensitive and recently described early-peak criterion is often false positive. Hydrogen breath test is useful to diagnose various types of sugar malabsorption. Technique and interpretation of different hydrogen breath tests are outlined in this review.

Keywords: Breath tests; Hydrogen; Intestine, small; Irritable bowel syndrome.

Figure 1

A schematic diagram that shows principle of hydrogen breath test. SIBO, small intestinal bacterial overgrowth; ppm, parts per million.

Figure 2

Some typical hydrogen breath test graphs are shown. It shows glucose hydrogen breath test negative for small intestinal bacterial overgrowth (SIBO) (A), glucose hydrogen breath test positive for SIBO (B), lactose hydrogen breath and tolerance test negative for lactose malabsorption (C) and lactose hydrogen breath and tolerance test positive for lactose malabsorption (D). It shows a graph negative for fructose malabsorption (E) and a graph positive for fructose malabsorption (F). ppm, parts per million; FBS, fasting blood sugar; PPBS, post-prandial blood sugar.