If you are taking anti-TNF agents to control inflammatory bowel disease (IBD) and you still have evidence of active disease, the American Gastroenterology Association (AGA) recommends therapeutic drug monitoring.
Therapeutic drug monitoring consists of conducting blood tests from which your doctor evaluates the amount of IBD drug in your blood, called a trough concentration. Knowing your trough concentration helps your doctor assess whether you have the optimal level of medication in your blood; it also enables your doctor to make sure you haven’t developed antibodies that may prevent the drug from working.
If you’re symptomatic despite having high trough level concentrations, you may need a different class of drug; if you are symptomatic with low trough levels and without high levels of antibodies, you may simply need an escalated dose. The AGA makes no recommendation for routine monitoring in inactive disease.
Monitoring is also recommended in patients taking thiopurines to avoid serious side effects. Before patients are started on thiopurines, the AGA recommends testing for an enzyme called TPMT, which helps break down these drugs. About 10 percent of patients are deficient in the enzyme and may need to be started on a lower drug dose. In symptomatic patients, therapeutic drug monitoring will help your doctor determine whether to raise the dosage or switch drugs.
The complete guideline was published last fall in the journal Gastroenterology.