What causes cpk levels in the 5000 range and what problems would it cause?

Many things: CPK gets released when muscles in the body are broken down. This can happen for a number of reasons - seizures, intense exercise, autoimmune conditions, medication side effects, and genetic conditions. If your muscles become heavily damaged very quickly, the substances they release can cause kidney problems.

Lots of causes: Elevated CPK indicates muscle damage and can be resolving or ongoing. There are many causes of this, but the main issue is that it can lead to kidney failure since the muscle breakdown proteins aren't filtered well by the kidneys. Also, ongoing muscle damage can lead to compartment syndrome, a surgical emergency.