Stress is an unavoidable part of modern life. Whether it stems from work pressures, financial concerns, relationship challenges, or health worries, stress affects us all to varying degrees. What many people do not realise is that chronic stress leaves measurable traces in your blood, and understanding these markers can provide valuable insights into your health.
At the centre of your body's stress response is cortisol — often called the "stress hormone." This article explores the relationship between stress, cortisol, and what your blood test results can reveal about how stress is affecting your body.
What Is Cortisol?
Cortisol is a steroid hormone produced by the adrenal glands, which sit atop your kidneys. It plays essential roles in numerous body functions:
Under normal circumstances, cortisol follows a predictable daily pattern called the diurnal rhythm. Levels are highest in the early morning (helping you wake up) and gradually decline throughout the day, reaching their lowest point around midnight.
The Stress Response and Cortisol
When you encounter a stressful situation, your body activates the hypothalamic-pituitary-adrenal (HPA) axis — a complex communication system between your brain and adrenal glands. This triggers the release of cortisol, preparing your body to deal with the perceived threat.
The acute stress response:
This "fight or flight" response evolved to help our ancestors survive immediate physical dangers. The problem arises when stress becomes chronic, keeping cortisol levels elevated for extended periods.
The Effects of Chronic Stress on Your Body
While short-term cortisol elevation is protective, prolonged high cortisol has widespread negative effects:
Metabolic effects:
Immune system effects:
Cardiovascular effects:
Mental health effects:
Other effects:
How Stress Affects Your Blood Test Results
Chronic stress can influence numerous blood markers, sometimes in ways that might be attributed to other conditions. Understanding these effects helps you and your healthcare provider interpret results accurately.
Blood glucose and HbA1c:
Cortisol raises blood sugar levels by promoting glucose production in the liver and reducing insulin sensitivity. Chronic stress can elevate fasting glucose and even push HbA1c into prediabetic ranges. For more information about blood sugar testing, read our guide to understanding the A1C blood test.
Lipid profile:
Stress hormones affect fat metabolism, often leading to elevated total cholesterol, LDL cholesterol, and triglycerides. HDL ("good") cholesterol may decrease. These changes increase cardiovascular risk.
Inflammatory markers:
While cortisol is anti-inflammatory in the short term, chronic stress paradoxically increases inflammation. You may see elevated C-reactive protein (CRP) and other inflammatory markers. Learn more in our overview of the C-reactive protein test.
Thyroid function:
Chronic stress can affect thyroid hormone conversion, potentially leading to symptoms of low thyroid despite normal TSH levels. The relationship between stress and thyroid function is complex and bidirectional. Discover more in our article on whether low thyroid can cause headaches.
Full blood count:
Stress can affect white blood cell counts and distribution. Chronic stress may cause elevated neutrophils and reduced lymphocytes — a pattern sometimes called "stress leukocytosis."
Electrolytes:
Cortisol affects sodium and potassium balance, potentially causing subtle electrolyte abnormalities.
Testing Cortisol Levels
If you suspect chronic stress is affecting your health, cortisol testing can provide valuable information. For comprehensive details on cortisol testing, read our article on how the cortisol blood test assesses your stress hormones.
Types of cortisol tests:
Interpreting cortisol results:
Managing Stress to Improve Your Health
If blood tests suggest stress is affecting your health, addressing the underlying stress is essential. Evidence-based strategies include:
Lifestyle modifications:
Mind-body practices:
Social and psychological support:
When to Seek Medical Advice
Consider consulting a healthcare provider if you experience:
A comprehensive blood test can help identify how stress may be affecting your body and guide appropriate interventions. For an overview of important tests, read our guide to the top 10 important blood tests.
Cortisol and Hormone Testing in London
At Private Blood Tests London, we offer cortisol testing and comprehensive hormone panels at our CQC-registered clinic in South Kensington. Our experienced healthcare team can help you understand how stress may be affecting your health and guide you toward appropriate next steps.
Explore our [comprehensive health screening packages](/health-screening) and learn about [hormone imbalance symptoms](/blog/hormone-imbalance-symptoms-you-shouldnt-ignore).
Understanding your body's stress response is the first step toward better health. Book your cortisol blood test today and take control of your wellbeing.