What is Hypothyroidism in Adults ? In hypothyroidism in adults, metabolic processes slow down because of a deficiency of the thyroid hormones triiodothyronine (T3) or thyroxine (T4). Hypothyroidism is classified as primary or secondary. Primary hypothyroidism stems from a disorder of the thyroid gland itself.
Fentanyl will definitely show up in a drug test and it will show up as an opiate because it is part of the class of drugs that are chemically similar to morphine.
Again, most urine drug tests are designed to detect the illicit (unprescribed) use of narcotics, scheduled substances (like benzodiazepines), and illegal substances (like marijuana). Your gabapentin usage shouldn't influence a urine drug test in any way.