Simplify the following text for a Grade 5 native English-speaking person.
Original: After 3 â `` 8 hours , myoglobin as a result of muscle breakdown may start to show up in the blood plasma , which can cause the urine to turn a dark reddish , brown , or black color , and eventually lead to acute renal failure .
Simplified: This is a result of muscle breakdown . It can cause the urine to turn a dark reddish , brown , or black in color , and eventually lead to kidney failure .