Critical illness myopathy and neuropathy

Labs
Titin is a sarcomere protein that serves as a spring for muscle extension and viscoelasticity. Elevated urinary titin reflects muscle breakdown. In one study of 56 nonsurgical critically ill patients, urinary titin increased 10-30 times above the normal level. When measured cumulatively on ICU days 2, 3, 5, and 7,higher levels were associated with lower limb muscle atrophy, ICU-acquired weakness, and ICU mortality.