Final answer:
c. muscle weakness. The nurse should monitor the client for muscle weakness.
Step-by-step explanation:
Hypomagnesemia, a condition characterized by abnormally low levels of magnesium, can have various manifestations. In the case of a client who developed hypomagnesemia due to long-term therapy with lansoprazole, the nurse should monitor the client for muscle weakness. Muscle weakness is a common symptom of hypomagnesemia and occurs due to the role magnesium plays in muscle function and contraction.
While hypomagnesemia can also lead to other manifestations such as cardiac arrhythmias, hypotension, and neuromuscular irritability, muscle weakness is specifically associated with low levels of magnesium.