From the Guidelines
The most appropriate study for diagnosis in this case would be paired measurement of serum cortisol and plasma ACTH, as recommended by the consensus statement on the diagnosis of primary adrenal insufficiency 1. The patient's symptoms, including fatigue, decreased appetite, weekly episodes of diarrhea, and unintentional weight loss, along with physical exam findings of darkening of the mucous membranes and skinfolds, are suggestive of primary adrenal insufficiency.
- The hyperpigmentation is a key finding that increases clinical suspicion of primary adrenal insufficiency, as it is caused by elevated ACTH levels that stimulate melanocyte-stimulating hormone receptors when cortisol production is inadequate 1.
- Additional helpful studies would include a synacthen (tetracosactide) stimulated serum cortisol test, which can confirm the diagnosis of primary adrenal insufficiency if the peak serum cortisol is <500 nmol/L 1.
- A comprehensive metabolic panel to check for electrolyte abnormalities, such as hyponatremia and hyperkalemia, would also be useful in supporting the diagnosis.
- If primary adrenal insufficiency is confirmed, the patient will require lifelong glucocorticoid replacement therapy, typically with hydrocortisone 15-25 mg daily in divided doses, and possibly mineralocorticoid replacement with fludrocortisone 1.
- Patients should also be educated about stress dosing during illness and the importance of carrying medical identification indicating their condition 1.
From the Research
Symptoms and Possible Diagnoses
The patient's symptoms include:
- Fatigue
- Decreased appetite
- Weekly episodes of diarrhea
- Unintentional weight loss
- Darkening of the mucous membranes and skinfolds
These symptoms could be indicative of adrenal insufficiency, as suggested by the darkening of the mucous membranes and skinfolds, which is a common sign of Addison's disease 2.
Diagnostic Tests
To diagnose adrenal insufficiency, various tests can be used, including:
- Laboratory tests to measure cortisol and ACTH levels
- Physical examination to assess for signs of adrenal insufficiency
- Imaging studies to rule out other causes of symptoms
The study by 3 discusses the use of circadian hydrocortisone infusions in patients with adrenal insufficiency, which may be relevant to the patient's treatment, but does not directly address the diagnostic process.
Interpretation of Diagnostic Tests
The interpretation of diagnostic test results depends on the ability of the test to distinguish between diseased and non-diseased individuals, as well as the patient's specific characteristics and the setting in which the test is being used 4, 5.
Relevant Studies
The study by 6 discusses the diagnostic accuracy of various tests, including history, physical examination, laboratory tests, and point-of-care ultrasound, in the diagnosis of acute appendicitis, which is not directly relevant to the patient's symptoms. However, it highlights the importance of considering multiple factors when interpreting diagnostic test results.
Next Steps
Based on the patient's symptoms and physical examination findings, further testing, such as laboratory tests to measure cortisol and ACTH levels, may be necessary to confirm a diagnosis of adrenal insufficiency 2.