Table 2.
The percentage of IBS subtypes and the diagnostic methods and thresholds used in the analyzed studies
| First author, year, reference number | IBS subtypes (%) | Diagnostic method for LM | Amount of lactose (g) | Diagnostic threshold for LM |
|---|---|---|---|---|
| Bianchi Porro et al. (1983)35 | No data | LBT, LTT, lactase activity (jejunal biopsy) |
LBT: 50 LTT: 100 |
LBT: >20 ppm H2 rise LTT: <20 mg/100 mL rise of blood glucose lactase activity: ≤39 IU/g protein |
| Gwee et al. (1996)36 |
IBS‐D: 86 IBS‐C: 9 IBS‐M/A: 5 |
LBT | 50 | No data |
| Vesa et al. (1998)37 | No data | LTT | 50 | Blood glucose elevation <1.1 mmol/L (20 mg/100 mL) and maximal rise in blood galactose concentration ≤0.3 mmol/L (5 mg/100 mL) |
| Goldstein et al. (2000)38 | No data | LBT | 18 | ≥20 ppm rise of H2 or ≥5 ppm rise of CH4 over baseline value |
| Vernia et al. (2001)27 |
IBS‐D: 24.8 IBS‐C: 13.3 IBS‐M/A: 17.1 |
LBT | 0.5 g/kg body weight up to a maximum of 25 g | H2 peak exceeding 20 ppm over the baseline values |
| Parry et al. (2002)39 | No data | LBT, LTT | 50 | A failure of plasma glucose to rise by more than 1.1 mmol/L from baseline. A rise in the breath hydrogen value above 20 ppm from baseline |
| Lanng et al. (2003)40 | No data | LTT | 50 | Glucose level rise ≤1.3 mmol/L |
| Farup et al. (2004)41 | No data | LBT | 25 |
Peak values of H2 breath excretion >20 ppm above the lowest preceding value, peak CH4 excretion >12 ppm above baseline, and/or combined H2 and CH4 increase >15 ppm were considered diagnostic |
| Saberi‐Firoozi et al. (2007)42 | No data | ‐ | ‐ | ‐ |
| Corlew‐Roath et al. (2009)43 | No data | LBT | 50 | H2, CH4, and CO2 were tested (threshold: no data) |
| Yakoob et al. (2011)44 | IBS‐D: 100 | LBT | 50 | H2 rise above baseline of 20 ppm |
| Kumar et al. (2012)45 |
IBS‐D: 52 IBS‐C: 35 IBS‐M/A: 13 |
Genetic test | ‐ | C/T_13910 (CC genotype)/G/A_22018 genetic variant (GG genotype) |
| Yang et al. (2013)26 | IBS‐D: 100 | LBT, genetic test | 10, 20, 40 | ≥20 ppm H2 rise above the baseline, C/T_13910 (CC genotype) |
| Xiong et al. (2014)46 | IBS‐D: 100 | LBT | 25 | Peak hydrogen breath excretion of 20 ppm above the baseline level |
IBS‐D/C/M/A, irritable bowel syndrome‐diarrheal/constipation/mixed/alternating subtype; LBT, lactose breath test; LM: lactose maldigestion; LTT, lactose tolerance test.