Department of Gastroenterology;
The First People’s Hospital of Hangzhou;
Department of Gastroenterology;
Sir Run Run Shaw Hospital affiliated to College of Medicine;
Zhejiang University;
Division of Gastroen- terology and Hepatology;
University Hospital Zürich;
NIHR Nottingham Digestive Diseases Biomedical Research Unit;
Queen’s Medical Centre;
Lactose; hydrogen; breath; test; Diagnosis; Lactose; malabsorption; Lactose; intolerance; Irritablebowel; syndrome;