Symptom Guide

Bloating

Name: Bloating: Causes, Blood Tests & When to Investigate
Creator: Suman Konda
Published: 2026-07-05

Bloating is extremely common and usually harmless, but persistent bloating can signal coeliac disease, thyroid issues, or ovarian pathology. Here's what tests reveal.

Written by Suman Konda, PharmD, Clinical Pharmacist · Editorial policy · Not medical advice

Last updated: 01 August 2026 · How we check our content

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?

Frequently Asked Questions

When is bloating a sign of something serious?

Persistent new bloating, especially in women over 50, or with weight loss, appetite change, or feeling full quickly, should be assessed to exclude ovarian and other cancers, even though most bloating is benign.

What everyday habits reduce bloating?

Eating more slowly, cutting fizzy drinks, identifying trigger foods (often high-FODMAP items), staying hydrated, and treating constipation resolve bloating for many people.

Can bloating be caused by food intolerance?

Yes. Lactose intolerance and IBS-related sensitivities to certain carbohydrates are common causes. A food and symptom diary helps identify the pattern before any testing.