Will morning coffee consumption affect morning laboratory tests for adrenal insufficiency (Adrenal Insufficiency) testing, specifically cortisol (Corticosteroid) levels?

From the Guidelines

Morning coffee consumption should be avoided before adrenal testing for adrenal insufficiency as it can potentially affect the accuracy of the test results. Although the provided evidence does not directly address the impact of morning coffee on adrenal testing, it is known that caffeine can stimulate the adrenal glands to release cortisol, which could artificially elevate cortisol levels in test results 1. For accurate adrenal function testing, it is recommended to abstain from coffee and other caffeinated beverages for at least 12-24 hours before the blood draw.

Key Considerations

• The diagnostic test for primary adrenal insufficiency involves paired measurement of serum cortisol and plasma ACTH, and any substances that could alter these levels should be avoided 1.
• Morning cortisol tests are typically scheduled between 7-9 AM when cortisol levels are naturally at their highest.
• Other factors that can affect results include stress, strenuous exercise, and certain medications, so it is essential to remain calm before the test and inform your doctor about any medications you're taking.

Recommendations for Accurate Test Results

• Avoid coffee and other caffeinated beverages for at least 12-24 hours before the blood draw.
• Fast from all food and beverages except water for 8-12 hours before the test, as instructed by your healthcare provider.
• Remain calm before the test and avoid strenuous exercise.
• Inform your doctor about any medications you're taking that could potentially affect the test results. By following these guidelines, you can help ensure that your adrenal function test results are accurate and reliable for proper diagnosis.

From the Research

Adrenal Insufficiency Testing

The question of whether morning coffee affects morning labs for adrenal testing for adrenal insufficiency is complex and requires consideration of various factors.

• The studies provided do not directly address the impact of morning coffee on adrenal insufficiency testing 2, 3, 4, 5, 6.
• However, it is known that cortisol levels can be affected by various factors, including time of day, with levels typically being higher in the morning 4, 5.
• The use of a morning cortisol level as a predictor of adrenal sufficiency has been studied, with proposed cutoff values ranging from 236 nmol/l to 444.7 nmol/l 4, 5, 6.
• It is also important to note that the diagnostic value of a single measurement of serum cortisol as a first step in the investigation of suspected adrenal insufficiency remains unclear, and further testing such as the short synacthen test (SST) or insulin tolerance test (ITT) may be necessary 2, 3, 4, 5, 6.

Factors Affecting Cortisol Levels

Several factors can affect cortisol levels, including:

• Time of day, with levels typically being higher in the morning 4, 5
• Type of assay and sample source used for cortisol measurement 2, 3
• Clinical presentation and likelihood of adrenal insufficiency before testing 2
• Technical aspects such as the type of test used (e.g. SST or ITT) 2, 3, 4, 5, 6

Diagnostic Criteria

Proposed diagnostic criteria for adrenal insufficiency based on morning cortisol levels include:

• A morning serum cortisol level <83 nmol/L is diagnostic for central adrenal insufficiency (CAI) 6
• A morning serum cortisol level >414 nmol/L excludes CAI 6
• A morning serum cortisol level between 83 and 414 nmol/L requires stimulation tests 6
• A basal cortisol value of >236 nmol/l can predict adrenal sufficiency with sensitivity 84% and specificity 71% 5
• A basal cortisol value of >375 nmol/l can predict adrenal sufficiency with sensitivity and specificity of 95% 5