Certified Neuroscience Registered Nurse (CNRN) Practice Exam

Which additional condition may be present in patients with untreated vitamin B12 deficiency?

1. Peripheral neuropathy

2. Diabetes mellitus

3. Thyroid disorder

4. Cardiac arrhythmia

The correct answer is: Peripheral neuropathy

Peripheral neuropathy is a common condition associated with untreated vitamin B12 deficiency. Vitamin B12 plays a crucial role in the production and maintenance of the myelin sheath, which insulates nerve fibers. A deficiency can lead to damage of the peripheral nerves, resulting in symptoms such as tingling, numbness, and pain in the extremities. This neurological manifestation occurs because B12 is essential for the synthesis of certain fatty acids and is vital for normal nerve functioning. In patients with untreated vitamin B12 deficiency, the longer the deficiency persists, the greater the risk of developing neurological deficits, including peripheral neuropathy. This condition emphasizes the importance of prompt diagnosis and treatment of vitamin B12 deficiency to prevent irreversible nerve damage and associated complications.