There are still other causes of fatigue as well such as anemia, nutritional deficiencies, heart problems, lung problems, medications, etc.
And adrenal problems can cause thyroid issues.
Other symptoms of adrenal dysfunction can include allergies/asthma, autoimmune disorders, blood pressure drops/dizziness upon sudden standing, water retention, chronic inflammation, easily stressed or get upset easily, hormone imbalances, and blood sugar drops when you don't eat.