What is considered adequate tacrolimus trough levels 4 years post transplant? For example the lab test says 5.0 - 20.0 ng/mL is the standard range. But is this for OLT or Kidney or other types of transplants? I've heard for OLT it can be a bit lower for stable OLT patients who've never had rejection issues. In your opinion is 2~3 ng/mL too low?