Differential Diagnosis for Shakiness, Fatigue, Muscle Weakness

Single Most Likely Diagnosis

• Hypothyroidism: This condition is a common cause of fatigue, muscle weakness, and shakiness due to the decreased production of thyroid hormones, which are essential for energy production and muscle function.

Other Likely Diagnoses

• Anxiety Disorder: Anxiety can cause shakiness (tremors), fatigue, and muscle weakness due to the body's stress response.
• Chronic Fatigue Syndrome: Characterized by persistent fatigue, muscle weakness, and other symptoms that cannot be explained by other medical conditions.
• Vitamin D Deficiency: Can lead to muscle weakness, fatigue, and other symptoms, especially in individuals with limited sun exposure or inadequate dietary intake.
• Diabetes (early stages or well-controlled): Although blood sugar is normal, early or well-managed diabetes can still cause symptoms like shakiness, fatigue, and muscle weakness due to fluctuations in blood glucose levels.

Do Not Miss Diagnoses

• Hyperthyroidism: Although less likely given the normal vitals, hyperthyroidism can cause shakiness (tremors), fatigue, and muscle weakness due to excessive thyroid hormone production.
• Pheochromocytoma: A rare tumor of the adrenal gland that can cause episodic symptoms including shakiness, fatigue, and muscle weakness due to excessive catecholamine release.
• Multiple Sclerosis: An autoimmune disease affecting the brain and spinal cord, which can present with a wide range of symptoms including muscle weakness and fatigue.
• Myasthenia Gravis: An autoimmune disorder that leads to muscle weakness and fatigue, which worsens with activity and improves with rest.

Rare Diagnoses

• Mitochondrial Myopathies: A group of disorders that affect the mitochondria, leading to muscle weakness, fatigue, and other symptoms due to impaired energy production.
• Wilson's Disease: A genetic disorder that leads to copper accumulation in the body, causing neurological symptoms including tremors, muscle weakness, and fatigue.
• Amyotrophic Lateral Sclerosis (ALS): A progressive neurological disease that affects nerve cells in the brain and spinal cord, leading to muscle weakness and fatigue.
• Adrenal Insufficiency: A condition where the adrenal glands do not produce adequate amounts of hormones, leading to fatigue, muscle weakness, and other symptoms.