Tacrolimus
Also known as: FK506; TAC
[Often referred to its brand name (see MedlinePlus Drug Information)]
[Often referred to its brand name (see MedlinePlus Drug Information)]
Formal name: Tacrolimus
Related tests: Ciclosporin; Therapeutic drug monitoring; Urea; Creatinine; Electrolytes; Potassium; Magnesium; Glucose
The Test Sample
What is being tested?
This test measures the amount of tacrolimus in the blood. Tacrolimus is an immunosuppressive drug that is given orally or intravenously to patients who have had a kidney, liver, heart, or other organ transplant. Normally, a person’s immune system would recognize the new organ as foreign and begin to attack it. Tacrolimus limits this response and helps to prevent organ rejection by reducing the activity of T-lymphocytes.
Tacrolimus levels in the blood must be kept within a narrow therapeutic range. If the concentration is too low organ rejection may occur, if it is too high then the patient may have symptoms associated with toxicity. Dosages must be adjusted to an individual. Often patients will begin with higher doses of tacrolimus at the start of therapy and then decrease the dose over the next few weeks. Tacrolimus is usually taken twice a day at set intervals before or after meals. When a person takes a dose, blood concentrations rise and peak within about 2 to 3 hours and then begin to slowly drop. The blood test is usually measured as a “trough” level. It is timed so that the collection is 12 hours post dose, and/or prior to the next dose – at the drug’s lowest concentration in the blood.
Tacrolimus levels in the blood must be kept within a narrow therapeutic range. If the concentration is too low organ rejection may occur, if it is too high then the patient may have symptoms associated with toxicity. Dosages must be adjusted to an individual. Often patients will begin with higher doses of tacrolimus at the start of therapy and then decrease the dose over the next few weeks. Tacrolimus is usually taken twice a day at set intervals before or after meals. When a person takes a dose, blood concentrations rise and peak within about 2 to 3 hours and then begin to slowly drop. The blood test is usually measured as a “trough” level. It is timed so that the collection is 12 hours post dose, and/or prior to the next dose – at the drug’s lowest concentration in the blood.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
Have the sample collected 12 hours after the last dose and/or immediately prior to the next dose or as directed by your doctor
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