| Common causes |
- Sleep- or fatigue-related (eg, insomnia)
- Nutritional deficiency (eg, low energy availability-relative energy deficiency in sport)
- Anemia (eg, iron deficiency)
- Psychological disorder (eg, depression, anxiety, eating disorder)
- Sport-related (eg, overreaching, fatigue following multiple competitions)
|
| Endocrine |
- Thyroid disease (hypothyroidism relatively common)
- Diabetes mellitus
- Adrenocortical insufficiency or excess
|
| Cardiopulmonary |
- Cardiomyopathy (eg, hypertrophic cardiomyopathy)
- Congenital or acquired heart disease (eg, septal defects, aortic stenosis, coarctation of aorta, coronary disease, supraventricular tachycardia, preexcitation syndrome [eg, Wolff-Parkinson-White])
- Chronic pulmonary disease
|
| Infectious |
- Post-viral syndrome
- Infectious mononucleosis
- Respiratory infection
- Hepatitis
- HIV
- Malaria
|
| Drug-related |
- Medication side effects (eg, antidepressant, anxiolytic, sedative-hypnotic, antihistamine, beta blocker)
- Substance abuse (eg, alcohol, marijuana)
|
| Neurologic |
- Post-concussive syndrome
- Neuromuscular disorder (eg, glycogen storage disease [eg, McArdle disease], later-onset muscular dystrophy)
|
| Other conditions |
- Environmental allergies
- Pregnancy
- Malignancy
- Chronic renal disease
- Celiac disease
|
