Methane breath tests and blood sugar tests in children with suspected carbohydrate malabsorption

Abstract

Carbohydrate malabsorption and subsequent gastrointestinal symptoms are a common clinical problem in pediatrics. Hydrogen (H₂) and methane (CH₄) breath tests are a cheap and non-invasive procedure for diagnosing fructose and lactose malabsorption (FM/LM) but test accuracy and reliability as well as the impact of non-hydrogen producers (NHP) is unclear. CH₄ breath tests (MBT), blood sugar tests (BST) and clinical symptoms were compared with H₂ breath tests (HBT) for FM/LM. 187/82 tests were performed in children (2 to 18 years) with unclear chronic/recurrent abdominal pain and suspected FM/LM. In FM and LM, we found a significant correlation between HBT and MBT/BST. In LM, MBT differentiated most of the patients correctly and BST might be used as an exclusion test. However, additional MBT and BST had no diagnostic advantage in FM. NHP still remain a group of patients, which cannot be identified using the recommended CH₄ cut-off values in FM or LM. Reported symptoms during breath tests are not a reliable method to diagnose FM/LM. Overall a combined test approach might help in diagnosing children with suspected carbohydrate malabsorption.

Figure 1

ROC curve analysis for blood sugar tests (a) and methane breath tests (b) in the diagnosis of fructose/lactose malabsorption. (a) Blood sugar was measured before administering the test sugar solution at baseline (0 min) and at 15/30/45/60 min and delta values were calculated. The highest blood sugar delta value was used and compared with the results of the corresponding hydrogen breath test (true positive). (b) ROC curve analysis for methane (CH₄) breath tests in patients with suspected fructose and/or lactose malabsorption. CH₄ was measured before administering the test sugar solution at baseline (0 min) and at 30/60/90/120 /150/180 min. The highest CH₄ value was used and compared with the results of the corresponding hydrogen breath test (true positive).

Figure 2

Time course analysis of endexpiratory hydrogen (H₂) and methane (CH₄) concentrations during hydrogen/methane breath tests (HBT/MBT) performed in children with suspected carbohydrate malabsorption. Shown are the hydrogen (a,c) and methane (b,d) concentrations during breath tests performed with fructose (a,b) and lactose (c,d). A positive HBT (H₂ positive) was defined by an increase of H₂ ≥ 20 ppm at 30/60/90/120 /150/180 min after administering of the respective test sugar solution. A CH₄ concentration ≥ 10 ppm at any measurement was considered as a positive MBT (CH₄ positive). Patients with an elevated baseline value (0 min: H₂ > 20 ppm/CH₄ ≥ 10 ppm) were excluded. Error bars at any given time are showing the standard error of the mean.

Figure 3

Parallel blood sugar testing and hydrogen breath test (HBT) in children with suspected carbohydrate malabsorption. Time course analysis of blood sugar levels in children with suspected fructose (a,b) and lactose (c,d) malabsorption. A positive HBT (H₂ positive) was defined by an increase of H₂ ≥ 20 ppm at 30/60/90/120 /150/180 min after administering fructose/lactose. Patients with an elevated H₂/CH₄ baseline value (0 min: H₂ > 20 ppm/CH₄ ≥ 10 ppm) were excluded. Blood sugar levels were measured before administering the test sugar solution (0 min, “baseline”) and at 15/30/45/60 min. Shown are the total blood sugar values (a,c) or the blood sugar delta values (b,d). Error bars indicate the standard error of the mean.