Wellness . Symptoms guide
Unexplained Weight Loss: When to Test
Unexplained weight loss of more than 5 percent body weight over 6 to 12 months without intentional change warrants assessment. The most common medical causes include hyperthyroidism, undiagnosed diabetes, coeliac disease and inflammatory or infective processes. Bloodwork is the right first step alongside a GP review.
This patient information is being clinically reviewed by our team. The factual content draws on UK guidance (NHS, NICE, British Association of Dermatologists, British Society for Sexual Medicine where cited).
What this might be
- Hyperthyroidism. Raised T3, T4, suppressed TSH.
- Diabetes (new diagnosis). Type 1 in particular can present with weight loss.
- Coeliac disease. Not in standard panel but addable on clinician advice.
- Inflammatory bowel disease. CRP, ESR, full blood count provide signals.
- Malignancy. Rare but always considered; bloodwork sometimes helps risk-stratify.
When to seek urgent advice
If any of the following apply, please contact your GP, NHS 111, or A&E in the first instance rather than waiting for private bloodwork.
- Rapid weight loss (more than 5 percent in 1 to 3 months)
- Night sweats
- Persistent abdominal pain or change in bowel habit
- Persistent fever
- Visible blood in stool, urine, or vomit
Common features that suggest this
- Weight loss not explained by diet or exercise
- Fatigue, anxiety, or palpitations
- Changes in bowel habit
- New persistent abdominal pain
Recommended tests
Same-day appointments at our Harley Street clinic, results clinician-reviewed.
Need a marker not in these panels? Build a custom panel and a GMC-registered clinician will design one for you.
Testing advice
Fasting recommended for General Wellness. Same-day appointment available. If red flags are present, please contact your GP or urgent care alongside private testing.
Common questions
Can private bloodwork replace a GP review?
For unexplained weight loss, both have a role. Bloodwork gives quick answers on the common causes. A GP review allows examination and onward referral if needed.