Cortisol - Total/AM

Introduction

As a functional medicine nurse practitioner in Florida, I frequently evaluate Cortisol – Total/AM levels to assess adrenal function. Accurate interpretation of these results is key to diagnosing conditions such as adrenal insufficiency and adrenal stress.

Introduction to Cortisol

Cortisol is the body’s primary glucocorticoid, produced by the adrenal glands. It supports:

• Blood Sugar Regulation: Promotes gluconeogenesis
  
• Metabolism: Modulates protein, fat, and carbohydrate metabolism
  
• Inflammation Control: Exerts anti-inflammatory effects
  
• Blood Pressure: Maintains vascular tone

   

Approximately 90% of circulating cortisol is bound to corticosteroid-binding globulin and albumin; the unbound fraction is biologically active.

The HPA Axis & Diurnal Rhythm

Cortisol secretion is governed by the hypothalamus-pituitary-adrenal (HPA) axis in a negative feedback loop:

1. CRH release from the hypothalamus
   
2. ACTH secretion by the pituitary
   
3. Cortisol production by the adrenals

    

Levels peak in the early morning (AM) and decline throughout the day, making both Total and AM cortisol measurements essential.

Cortisol Testing: Total vs. AM

• Total Cortisol: Reflects total bound + free cortisol in serum
  
• AM Cortisol: Captures morning peak output

   

Reference Ranges:

• Total Cortisol: 4.0 – 22.0 µg/dL (110–607 nmol/L)
  
• AM Cortisol (Optimal): 10.0 – 15.0 µg/dL (275–414 nmol/L)

   

Clinical Implications of Cortisol Levels

Low Cortisol Levels

• Adrenal Insufficiency: May present with fatigue, hyperkalemia, hyponatremia
  
• Adrenal Fatigue: Chronic stress leading to HPA axis dysregulation

   

High Cortisol Levels

• Adrenal Stress: Elevated cortisol due to chronic stress
  
• Cushing’s Syndrome: Prolonged cortisol excess (consider referral if suspected)

   

Other Considerations

• Low Cortisol: Suggests Addison’s Disease (often confirmed with ACTH stimulation)
  
• High Cortisol: Can result from exogenous steroids, estrogen therapy, or contraceptive use
  
  

   

Interfering Factors & Drug Associations

• Falsely Low: Contraceptive/estrogen use
  
• Falsely High: Acute illness, certain medications
  
• Drugs ↓ Cortisol: Antifungals, some antiseizure agents
  
• Drugs ↑ Cortisol: Glucocorticoid therapy

   

Related Tests

For a comprehensive adrenal evaluation, consider:

• Salivary Cortisol: Diurnal pattern confirmation
  
• Serum DHEA-S: Complementary adrenal marker
  
• Electrolytes (Na⁺, K⁺): Assess adrenal impact on balance
  
• Aldosterone/Renin: Renin-angiotensin-aldosterone axis

   

Conclusion

Accurate interpretation of Cortisol – Total/AM is essential for diagnosing and managing adrenal disorders. As a functional medicine practitioner, I integrate these biomarker insights with personalized nutrition, lifestyle interventions, and targeted therapies to address root causes of dysfunction. Learn more about our Functional Medicine approach or explore our Medical Weight Loss program for comprehensive metabolic support.

Further Reading

1. 1. Arlt, W., Allolio, B., & Hahner, S. (2006). Quality of glucocorticoid replacement in adrenal insufficiency. European Journal of Endocrinology, 154(6), 803-811.
      https://pubmed.ncbi.nlm.nih.gov/16584509/1

   2. Doi, S. A., et al. (2020). Serum morning cortisol as a screening test for adrenal insufficiency. Annals of Saudi Medicine, 40(1), 1-7.
      https://pubmed.ncbi.nlm.nih.gov/31461355/2

   3. Masopust, V., et al. (2016). The role of early cortisol level in the assessment of radicality of surgery for central Cushing’s disease. Videosurgery and Other Miniinvasive Techniques, 11(3), 223-230.
      https://pubmed.ncbi.nlm.nih.gov/27618608/3

   4. European Society of Endocrinology. (2023). European Society of Endocrinology clinical practice guidelines on the management of adrenal incidentalomas. European Journal of Endocrinology, 189(1), G1–G46.
      https://academic.oup.com/ejendo/article/189/1/G1/7198474