Final answer:
A serum calcium level of 11.9 mg/dL is indicative of hypercalcemia, not decreased muscle tone, which is more commonly associated with hypocalcemia. This condition can lead to sluggish reflexes and lethargy, contrasting with the muscle spasms seen in hypocalcemia.
Step-by-step explanation:
The statement that a serum calcium level of 11.9 indicates decreased muscle tone is false. Normal blood calcium levels, which contribute to proper muscle contractions and nerve impulses, are about 10 mg/dL. A level of 11.9 mg/dL, therefore, indicates hypercalcemia, a condition where calcium levels in the blood are too high.
Hypercalcemia can result in a variety of symptoms including lethargy, sluggish reflexes, constipation, and loss of appetite. In severe cases, it may lead to confusion and coma. It is hypocalcemia, or low levels of calcium, that can lead to increased muscle tone and tetany - which involves muscle twitching and spasms due to increased membrane permeability to sodium.