Fatigue and weakness may present individually or together as symptoms of another disorder. According to the American Academy of Family Physicians, weakness is the lack of physical or muscular strength and effort needed to move the body or engage in regular daily activity. Fatigue refers to the feeling of exhaustion and an overwhelming lack of energy. Persistent weakness and fatigue may be indicative of a more serious medical or psychological condition and warrant professional evaluation.
Psychological Cause
The Mayo Clinic recognizes fatigue as a common symptom of underlying mental health conditions, such as depression and stress. Depression symptoms can range from mild to severe with the severe symptoms including the inability to perform daily tasks. Depression involves a chemical imbalance of neurotransmitters responsible for pleasure and motivation as well as body components such as physical pain. Depression symptoms often change the way a person feels about himself and his life, further compounding the lack of energy, weakness and sadness. Stress can also overburden a person's physical and mental well-being.
Thyroid-Related Cause
The thyroid gland controls metabolism and the regulation of calcium in the blood. MedlinePlus.com indicates that an underactive or overactive thyroid gland may cause fatigue. Hypothyroidism, or deficient activity of the thyroid gland, has additional symptoms such as weight gain, depression and intolerance to cold temperatures. Hyperthyroidism, or excessive functional activity of the thyroid gland, can cause weight loss, anxiety and intolerance to heat. Each thyroid problem warrants medical intervention to decrease symptoms.
Diabetes
Type II diabetes symptoms include fatigue and weakness. This condition affects the way the body metabolizes sugar. The Mayo Clinic indicates this form of diabetes resists the effects of insulin, which regulates the movement of sugar in the body, causing a life-threatening condition if untreated. This condition causes fatigue because the cells become deprived of the necessary sugars required to maintain the body.
Multiple Sclerosis
A fast-growing nervous system disease called multiple sclerosis, or MS, causes symptoms of muscle weakness, fatigue and numbness. MedlinePlus.com indicates there is no known cause of MS; but when symptoms initiate, the body feels as if it is under attack from multiple symptoms. People between the ages of 20 and 40 years old have a higher risk of MS onset, with women at risk more than men. The disorder may begin as mild but as it progresses, it becomes debilitating. Medications may help control symptoms, but a cure currently does not exist for this disease.
