Fatigue and a new tan might seem like small, disconnected symptoms—but they can signal something serious.
In a recent case, a young patient presented with persistent fatigue and subtle hyperpigmentation, without many of the typical red flags that would immediately point to a clear diagnosis. From adrenal insufficiency to hemochromatosis, our community weighed the possibilities, offering insights based on their personal clinical experience. Their approaches reveal how careful consideration of labs and differentials can clarify even rare presentations.
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Post:
Patient was a 36 yo female who presented in February with fatigue over the last 4 weeks, no fever, weight loss, or sleep issues. Patient denies CP/SOB/Abd Pain or change in bowels, or night sweats. She is on no medications. Patient has normal periods. She is moderately tanned but denies tanning sessions. What tests would you check for your diagnosis? What would your Ddx be?
Questions for consult
1. What causes fatigue and a tan?
Comments
Key takeaways about causes of chronic fatigue and a tanned appearance:
- Addison’s disease leads the differential
Across clinicians, primary adrenal insufficiency is the most consistently cited cause, with clinicians quickly connecting fatigue and hyperpigmentation to elevated ACTH levels. - Broad differentials reflect diagnostic uncertainty
While Addison’s is top of mind, clinicians also consider hemochromatosis, thyroid disorders, malignancy, and even dietary causes—highlighting the need to rule out multiple systemic conditions. - Workup should start broad, then narrow
Most clinicians favor an initial wide lab panel—cortisol, ACTH, thyroid function, and iron studies—before moving to more targeted testing like ACTH stimulation or imaging.
Internal Medicine
"First thing that came to mind was autoimmune Addison’s disease. Second would be hemochromatosis. Hypothyroidism might be a remote possibility. Would order electrolytes, serum cortisol, ACTH, and ACTH stimulation test. Also, TSH, T4, iron, TIBC, ferritin, and transferrin. For completeness, after the lab performs adrenal imaging, if appropriate."
Internal Medicine
"Something totally unrelated, perhaps—unless onset of tan correlates to onset of fatigue. Primary adrenal insufficiency (i.e., Addison's) could be a cause or something intrinsic to adrenal glands (occult infection - exposure, travel history) or (malignancy). Check cortisol and ACTH level."
Family Practice
"Differential diagnosis includes Addison’s disease and hemochromatosis. I’m assuming that the patient’s entire body is tan, so photosensitivity from medications would not be likely. I would order a morning cortisol and possibly an ACTH stimulation test if the cortisol was low. I would also order a liver function iron, and ferritin."
Family Practice
"Addison's or primary adrenal insufficiency can cause fatigue and a tan. A very specific diet can cause similar symptoms, such as someone who prefers to eat carrots and does not incorporate other food groups in their diet."
Internal Medicine
"I would start with a simple CBC and chem profile, TSH, probably a sed rate, and a UA. Not sure what the tan thing is about, some rare genetic disease? One could also check iron studies for hemochromatosis."
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