Blood tests ordered for persistent bloating
| Test | What it checks for |
|---|---|
| tTG-IgA (tissue transglutaminase) | Coeliac disease — gluten sensitivity causing gut damage |
| Total IgA | IgA deficiency — falsely negative coeliac test if low |
| TSH | Hypothyroidism slows gut motility causing bloating |
| CA-125 | Ovarian cancer marker — ordered in women with persistent bloating |
| CRP / ESR | Inflammatory bowel disease |
| FBC | Anaemia from coeliac or IBD |
| Fasting glucose | Diabetes with gastroparesis |
Common causes of bloating
IBS — the most common diagnosis
Irritable bowel syndrome (IBS) causes bloating, abdominal pain, and altered bowel habits (constipation, diarrhoea or both). Blood tests are typically normal. Diagnosis is clinical using the Rome IV criteria. Triggers include FODMAPs (fermentable carbohydrates), stress, and gut dysbiosis. A low-FODMAP diet helps 50–70% of IBS patients.
Coeliac disease
Coeliac disease is an autoimmune reaction to gluten (in wheat, barley and rye) that damages the small intestine lining. Symptoms include bloating, diarrhoea, fatigue, and weight loss — but some people have minimal symptoms. The tTG-IgA blood test is the first-line screening test (sensitivity ~95%). Diagnosis is confirmed by small bowel biopsy. Treatment is strict lifelong gluten-free diet.
When bloating needs urgent investigation
See a doctor promptly if bloating is accompanied by: unintentional weight loss; blood in the stool; persistent change in bowel habit; bloating that doesn't come and go (constant abdominal distension); or a palpable abdominal mass. These features require investigation to rule out bowel cancer or ovarian cancer.
Questions to ask your doctor
- Should I be tested for coeliac disease?
- Do I need a colonoscopy?
- Could my thyroid be causing my sluggish digestion?
- Should I try a low-FODMAP diet?