Blood Test for Brain Fog
May 9, 2026
Blood Test for Brain Fog
A blood test for brain fog investigates the medical conditions that cause mental cloudiness, difficulty concentrating, and cognitive sluggishness—including thyroid dysfunction (especially hypothyroidism), vitamin B12 deficiency, iron deficiency, blood sugar dysregulation, hormonal imbalances, and chronic inflammation—because brain fog is a symptom with identifiable, treatable causes.
At Blood Test London, our brain fog investigation panel costs from £295 with results in 2-3 days. A doctor always reviews every result.
Common Causes of Brain Fog
Thyroid Dysfunction
Hypothyroidism is a major cause
Slowed metabolism affects brain function
Often missed with basic testing
Nutritional Deficiencies
B12 deficiency (neurological effects)
Iron deficiency (even without anaemia)
Vitamin D deficiency
Metabolic Issues
Blood sugar instability
Insulin resistance
Diabetes
Hormonal Causes
Perimenopause/menopause
Low testosterone
Cortisol imbalances
Other Factors
Inflammation
Anaemia
Sleep disorders (not tested by blood)
What We Test
Priority Panel
Full thyroid function (TSH, T4, T3)
Vitamin B12
Iron studies + ferritin
Fasting glucose + HbA1c
Full blood count
Extended Panel
Thyroid antibodies
Vitamin D
Cortisol
Hormones
Inflammation (CRP)
Our Brain Fog Testing Options
Essential Brain Fog Panel - £295
Thyroid function
B12, folate
Iron studies
Blood sugar markers
Full blood count
Doctor review
Comprehensive Brain Fog Panel - £395
All above plus:
Full thyroid with antibodies
Vitamin D
CRP
Detailed interpretation
Complete Cognitive Assessment - £495
Full panel
Hormone screen
Cortisol
Extended consultation
Book Your Test
Price: From £295
Results: 2-3 days
Doctor review: A doctor always reviews every result
Book via WhatsApp | Phone: 020 3951 3429
Blood Test London by The Wellness. Brain fog investigation from £295. A doctor always reviews every result.