Which vitamin is most likely to be deficient in patients on treatment with isoniazid :
**Core Concept**
Isoniazid is a first-line antitubercular medication that can interfere with the metabolism of certain nutrients, leading to deficiencies. The vitamin in question is crucial for neuronal function, and its deficiency can cause neurological symptoms.
**Why the Correct Answer is Right**
Isoniazid inhibits the enzyme pyridoxine kinase, which is necessary for the activation of vitamin B6 (pyridoxine). This inhibition leads to a decrease in the levels of the active form of vitamin B6, causing a deficiency. Vitamin B6 plays a crucial role in many bodily functions, including the synthesis of neurotransmitters, such as serotonin and dopamine, which regulate mood and cognitive function.
**Why Each Wrong Option is Incorrect**
**Option A:** Vitamin C is not directly affected by isoniazid treatment. Vitamin C deficiency can cause scurvy, a condition characterized by fatigue, malaise, and connective tissue weakness.
**Option B:** Vitamin B12 is not directly related to isoniazid's mechanism of action. Vitamin B12 deficiency can cause megaloblastic anemia, neurological symptoms, and gastrointestinal problems.
**Option C:** Folic acid is not directly affected by isoniazid treatment. Folic acid deficiency can cause megaloblastic anemia, fatigue, and weakness.
**Clinical Pearl / High-Yield Fact**
Isoniazid-induced vitamin B6 deficiency can be prevented or treated with pyridoxine supplements. It is essential to monitor patients on isoniazid therapy for signs of vitamin B6 deficiency, such as peripheral neuropathy, seizures, and cognitive impairment.
**Correct Answer: C. Vitamin B6**