Normal Reference Ranges
Adult
5.0 - 15.0 (Target dependent on organ/time post-transplant) ng/mL
Pediatric
Same as adult ng/mL
Clinical Significance
Monitors immunosuppression in transplant patients. Narrow therapeutic index; high levels cause nephrotoxicity and neurotoxicity, low levels lead to graft rejection.
Causes of High
- Tacrolimus toxicity
- CYP3A4 inhibitors (Grapefruit juice, Clarithromycin)
Causes of Low
- Subtherapeutic dosing
- CYP3A4 inducers (Rifampin)
- Non-compliance