Is a cortisol level of 6.98 micrograms per deciliter (mcg/dL) within the normal range?

Is a Cortisol Level of 6.98 mcg/dL Normal?

A cortisol level of 6.98 mcg/dL falls within the normal reference range for morning cortisol (5-23 mcg/dL), but interpretation depends critically on the timing of collection and clinical context. 1

Context-Dependent Interpretation

If Measured as Morning (8:00-9:00 AM) Cortisol

• This value is in the lower-normal range and may warrant further evaluation if you have symptoms of adrenal insufficiency 1, 2
• Morning cortisol <10 mcg/dL (<275 nmol/L) is concerning and should prompt ACTH stimulation testing if clinical suspicion exists 2
• Morning cortisol >14 mcg/dL effectively rules out adrenal insufficiency, so your value of 6.98 mcg/dL does not provide this reassurance 1

Key symptoms requiring further workup include: unexplained fatigue, weakness, hypotension, nausea/vomiting, weight loss, hyponatremia, or hyperkalemia 2, 3

If Measured After Dexamethasone Suppression Test

• This result is completely normal and reassuring 1
• Normal suppression should be <1.8 mcg/dL, but values up to 2 mcg/dL are acceptable 1, 4
• A value of 6.98 mcg/dL after dexamethasone would be abnormal and suggest autonomous cortisol secretion or Cushing's syndrome 1, 2

If Measured at Midnight or Late Evening

• This would be significantly elevated and highly concerning for Cushing's syndrome 1, 2
• Normal midnight cortisol should be <1.8 mcg/dL (<50 nmol/L) 1
• Midnight cortisol ≥1.8 mcg/dL has 100% sensitivity for Cushing's syndrome 2

Critical Factors Affecting Interpretation

Medications and Conditions That Falsely Elevate Total Cortisol

• Oral contraceptives or estrogen therapy dramatically increase cortisol-binding globulin (CBG), raising total cortisol while free cortisol remains normal 1, 5
• Pregnancy increases CBG and total cortisol 1
• Chronic active hepatitis elevates CBG 1

Factors That Falsely Lower Total Cortisol

• Nephrotic syndrome or malnutrition decrease CBG 2

Physiologic Stressors That Elevate Cortisol

• Acute illness, infection, or psychological stress 1
• Strenuous exercise within 24-48 hours 1

Recommended Next Steps

If you have symptoms of adrenal insufficiency (fatigue, weakness, hypotension, nausea):

• Proceed with ACTH stimulation test 1, 2
• Peak cortisol <18 mcg/dL (<500 nmol/L) after ACTH is diagnostic of adrenal insufficiency 1, 2

If this was a random or afternoon measurement:

• Repeat as a properly timed 8:00-9:00 AM cortisol 3
• Consider simultaneous ACTH measurement to distinguish primary from secondary adrenal insufficiency 3

If you are on oral contraceptives or estrogen:

• This may represent a falsely elevated total cortisol with normal free cortisol 1, 5
• Consider measuring free cortisol or salivary cortisol instead 1

Common Pitfalls to Avoid

• Never interpret cortisol without knowing the exact time of collection - the same value may be normal at 9:00 AM but pathologically elevated at midnight 3, 6
• Always inquire about oral contraceptives, estrogen therapy, and pregnancy before pursuing extensive workup for abnormal cortisol 1
• Do not delay treatment if acute adrenal crisis is suspected - administer IV hydrocortisone 100 mg immediately without waiting for results 2