Can adrenal adenomas cause excessive fatigue and weakness?

Yes: Yes, if they produce adrenal hormones in excess.

No: Adrenal adenomas are usually small, non functional lesions of the adrenal gland picked up by chance on an abdominal scan. they are non functional for the most part and as such asymptomatic. When lesions do function they produce either cortisone or adrenaline like substances not related to excessive fatigue or weakness but rather hypertension or Cushing like symptoms.