From the Guidelines
Yes, the hydrogen breath test is the most reliable method to diagnose lactose intolerance, involving drinking a lactose-containing liquid and measuring hydrogen levels in breath at regular intervals. This test is considered the most widely used and probably superior to lactose tolerance tests, with similar sensitivity and specificity to the mucosal lactase assay 1. The procedure involves ingestion of 25–50 g lactose dissolved in 200–500 ml water after an overnight fast, with end expiratory breath samples taken at 15–30 minute intervals for three hours. A rise of hydrogen concentration from basal levels by more than 20 parts per million is compatible with a positive diagnosis.
The lactose tolerance test and stool acidity test are also diagnostic methods, but the hydrogen breath test is preferred due to its ease of performance and non-invasive nature. It's essential to note that a negative result does not exclude the diagnosis, and a trial of a lactose-free diet should be considered if the diagnosis is still suspected 1. Other methods, such as genetic testing to identify lactase persistence, are less common in clinical practice.
The importance of proper diagnosis is highlighted by the fact that symptoms of lactose intolerance can mimic other digestive disorders, such as irritable bowel syndrome (IBS) 1. In fact, a study found that lactose malabsorption was present in 21-25% of patients with IBS criteria 1. Therefore, breath testing after carbohydrate challenge, such as the hydrogen breath test, could be useful in identifying the cause of symptoms and predicting response to therapy 1.
In clinical practice, it's crucial to prioritize the most recent and highest quality study, which in this case is the 2018 guidelines for the investigation of chronic diarrhoea in adults 1. This study emphasizes the importance of breath testing in diagnosing lactose intolerance and highlights the high prevalence of lactase deficiency worldwide. A positive lactose breath test can inform diagnosis and treatment, although avoidance of dairy products alone is rarely sufficient treatment in patients with IBS 1.
In summary, the hydrogen breath test is the most reliable method to diagnose lactose intolerance, and its results can inform diagnosis and treatment. Other diagnostic methods, such as the lactose tolerance test and stool acidity test, are also available, but the hydrogen breath test is preferred due to its ease of performance and non-invasive nature.
From the Research
Diagnosis of Lactose Intolerance
There are several tests available to diagnose lactose intolerance, including:
- Genetic test
- Hydrogen breath test (HBT)
- Quick lactase test
- Lactose tolerance test 2 The HBT is the most commonly used method due to its non-invasive nature, low cost, and high sensitivity and specificity 2, 3.
Hydrogen Breath Test (HBT)
The HBT measures the amount of hydrogen in a person's breath after consuming a lactose-containing substance 3, 4.
- The test is based on the principle that undigested lactose is fermented by bacteria in the colon, producing hydrogen gas 3.
- The HBT is a popular diagnostic tool for lactose intolerance due to its relatively low cost, availability, and non-invasiveness 3.
Other Diagnostic Methods
Other diagnostic methods, such as blood tests, biopsies, and genetic tests, are also available but are less commonly used 3, 5.
- The lactose tolerance test measures the body's ability to digest lactose by monitoring blood sugar levels after consuming a lactose-containing substance 2, 5.
- Genetic tests can identify genetic variants associated with lactose intolerance, but are not yet widely used in clinical practice 2.
Clinical Practice
In clinical practice, the HBT is often used as the primary diagnostic test for lactose intolerance, with other methods used as secondary tests to confirm the diagnosis 2, 5.