Question

Adverse effects of Phenytoin include the following except:

• A. Lymphadenopathy.
• B. Ataxia.
• C. Hypercalcemia.
• D. Hirsutism.

Hint:

Phenytoin speeds vitamin D breakdown, causing hypocalcemia, not hypercalcemia.

Answer 1

The Correct Option is C

Concept:
Phenytoin's side effect list is often grouped by system: nervous system (ataxia, nystagmus), skin and connective tissue (hirsutism, gum overgrowth), immune/lymphatic (pseudolymphoma with lymphadenopathy), and bone/mineral metabolism.


Step 1: Confirm the nervous system effect.
High phenytoin levels affect the cerebellum, giving ataxia, unsteady gait and nystagmus. This is a dose related, well known toxicity.


Step 2: Confirm the lymphatic effect.
Long term phenytoin can trigger a benign but alarming pseudolymphoma reaction, with swollen lymph nodes that can mimic cancer.


Step 3: Confirm the skin/connective tissue effect.
Phenytoin is notorious for causing gum overgrowth, coarse facial features and hirsutism with long term use.


Step 4: Check the calcium claim.
Phenytoin speeds up liver breakdown of vitamin D. Less active vitamin D means less calcium absorbed from food, so calcium levels tend to fall, not rise, over time. This can lead to osteomalacia in chronic users. Hypercalcemia is the opposite of what phenytoin actually does.


Step 5: Conclude.
Since three options are true phenytoin effects and calcium moves down, not up, hypercalcemia is the exception.
\[ \boxed{\text{Hypercalcemia}} \]