When might a deep tendon reflex be less than 2?

• A. Pregnant woman or alcoholic on magnesium sulfate
• B. Seizure patient
• C. After exercise
• D. Dehydration

Answer: (A)

Deep tendon reflexes are graded on a scale where 2+ is normal. A value below 2+ indicates hyporeflexia, meaning the reflex arc is less responsive. In pregnancy, magnesium sulfate is commonly given to prevent eclampsia seizures. Magnesium acts as a central and peripheral nervous system depressant and blocks calcium entry at the neuromuscular junction, reducing acetylcholine release and dampening the reflex arc. This is why a pregnant woman on magnesium sulfate can have deep tendon reflexes that are less than normal.

The other scenarios don’t typically produce decreased reflexes in the same way. Seizure activity is more often associated with hyperreflexia due to CNS agitation; after exercise reflexes tend to be brisker as muscles heat and respond more readily; dehydration isn’t a reliable cause of reduced reflexes in this context.