Idiopathic Carpal Tunnel Syndrome: This is the most common cause of bilateral carpal tunnel syndrome, often related to repetitive strain, wrist anatomy, or fluid retention. It's a diagnosis of exclusion after ruling out other causes.

Diabetes Mellitus: Diabetes is a well-known cause of peripheral neuropathy, including carpal tunnel syndrome. The metabolic changes associated with diabetes can damage nerves, leading to symptoms of carpal tunnel syndrome.
Hypothyroidism: This condition can cause swelling of the soft tissues, including those in the wrist, leading to compression of the median nerve and symptoms of carpal tunnel syndrome.
Rheumatoid Arthritis: This autoimmune disorder can cause inflammation and swelling in the wrists, leading to compression of the median nerve.
Obesity: Excess weight can increase pressure on the wrists and contribute to the development of carpal tunnel syndrome.

Acromegaly: A rare hormonal disorder that can cause nerve compression symptoms, including carpal tunnel syndrome, due to soft tissue overgrowth.
Amyloidosis: A condition characterized by the deposition of abnormal proteins (amyloid) in various tissues, which can cause nerve damage and carpal tunnel syndrome.
Multiple Myeloma: A type of blood cancer that can lead to nerve damage and carpal tunnel syndrome through various mechanisms, including amyloid deposition.

Lipoma or Other Space-Occupying Lesions: Rarely, a tumor or cyst in the wrist can compress the median nerve, leading to carpal tunnel syndrome.
Sarcoidosis: An autoimmune disease that can cause inflammation and nerve damage, leading to carpal tunnel syndrome in rare cases.
Charcot-Marie-Tooth Disease: A group of inherited disorders that affect the peripheral nerves, potentially causing symptoms similar to carpal tunnel syndrome, though this is less common.