The purpose of the Tacrolimus test is to measure the concentration of tacrolimus in a person’s blood. Tacrolimus is an immunosuppressive medication administered orally or intravenously to people who have undergone organ...
Introduction
The purpose of the Tacrolimus test is to measure the concentration of tacrolimus in a person’s blood. Tacrolimus is an immunosuppressive medication administered orally or intravenously to people who have undergone organ transplantation, such as kidney, heart, liver, or other organs. This is a potent drug that plays an important role in preventing the rejection of the transplanted organ by the recipient's body.
What happens normally is that the immune system of the patient would identify the new organ as foreign and prepares to attack it. This is where Tacrolimus comes into play, mitigating this response by suppressing the activity of specific immune cells known as T-lymphocytes. This helps to prevent organ rejection.
For this, it is important to maintain tacrolimus levels within a narrow range in the bloodstream, because if the concentration is too low, the risk of organ rejection rises. On the other hand, excessive levels can lead to symptoms of toxicity.
Dosages of tacrolimus need to be given to each individual in a tailor-made fashion. Normally, patients are given higher doses of tacrolimus after a transplant. It is then gradually reduced over the next few weeks. Tacrolimus is administered to the patient twice a day, at specific intervals either before or after meals. After taking it, blood concentrations of the drug increase and reach their peak within approximately two to three hours, which is followed by a gradual decline. The blood test to monitor tacrolimus levels is usually done as a "trough" measurement.
This test is timed to collect the blood sample 12 hours after the dose or before giving the next dose when the drug's concentration is at it’s lowest in the blood.
Tacrolimus test: The process
The purpose of requesting a tacrolimus test is to determine the amount of the drug in the blood, ensuring that it falls within the therapeutic range and remains below toxic levels.
Monitoring tacrolimus levels is paramount for several reasons:
The correlation between the administered dose of tacrolimus and the resulting blood concentration of the drug is not good.
The absorption and metabolism of oral tacrolimus doses can vary significantly among patients, and even within the same patient, depending on factors such as the timing of the dose and whether any food has been consumed.
Tacrolimus, particularly at high doses, can potentially lead to kidney damage. Monitoring the levels of tacrolimus in individuals who have undergone kidney transplantation can help in distinguishing between kidney rejection (characterized by low blood levels) and kidney damage resulting from tacrolimus toxicity (marked by high blood levels).
Monitoring Tacrolimus helps ensure that each individual is given the right amount of drug for treating his or her particular case.
Under what circumstances the Tacrolimus test is requested?
At the start of therapy, tacrolimus testing is commonly requested, often daily, to ascertain the appropriate dosage regimen. Once the dosages have been established and has become apparent to be well tolerated, the frequency of tacrolimus testing may be reduced.
However, the test is still conducted when there are changes in dosages and whenever patients experience symptoms that may indicate side effects, toxicity, or organ rejection.
Following are some of the signs and symptoms of tacrolimus toxicity:
- Kidney damage (nephrotoxicity)
- High blood pressure
- Tremors, headache (neurotoxicity)
- Nausea and vomiting
- Imbalances in electrolytes, such as elevated levels of potassium
- Tinnitus -intermittent and/or continuous ringing or roaring in the ears
- Seizures
It is important to monitor at regular intervals till the patient is taking tacrolimus.
Interpretation of the test results
When concentrations of tacrolimus are high beyond the established therapeutic range it can increase the risk of toxicity, potentially causing harm to the kidneys and nerves. When concentrations are too low it may result in rejection of the transplanted organ. Side effects may occur at any dosage, but they generally appear to be more acute when tacrolimus levels are higher.
The therapeutic range for tacrolimus established by a laboratory is governed by both the measurement method that is used and the specific type of transplant. It is important to note that results obtained from different measurement methods are not interchangeable. Typically, doctors will ensure that their patients' samples are always sent to the same laboratory, and they will rely on the therapeutic ranges provided by that specific laboratory for guidance.
Other things to keep in mind
Several medicines can pose a threat to tacrolimus concentrations. Medicines such as calcium channel blockers, macrolide antibiotics, antifungal drugs, protease inhibitors, chloramphenicol, and another immunosuppressant are not conducive as they can lead to tacrolimus concentrations.
Patients who have experienced a negative reaction to macrolide antibiotics should avoid taking tacrolimus. It is worthwhile to mention that medications such as anticonvulsants, antimicrobials, and immunosuppressants have the potential to lower tacrolimus concentrations.
It is also advisable to avoid grapefruit juice and herbal supplements while one is taking tacrolimus. It is important to stick to the same brand of tacrolimus during the entire treatment and avoid switching between different formulations. The specific brand of tacrolimus prescribed by the doctor should be strictly followed.
Patients who have undergone bone marrow transplants may be given Tacrolimus for a certain period. Tacrolimus ointment is also useful in treating many skin diseases like eczema, which have not been cured with other medicines. This is a topical use of tacrolimus, meant to be local and not systemic. In these cases, the blood concentrations are also not closely watched. In some countries, tacrolimus is used for treating myasthenia gravis.
Patients need to follow the doctor’s instructions and they should never change their dose or the time of taking the medicine on their own. Patients should regularly take Tacrolimus along with their suggested diet. Food that is high in fat can block the amount of drug that reaches the circulation as opposed to taking the drug while fasting.
Pregnant women or women who are planning to become pregnant should consult with their doctors about the potential risk factors of taking Tacrolimus as it may have negative effects on the unborn child.
Conclusion
It is important to note that transplant patients must take tacrolimus for the rest of their lives. It could be a different immunosuppressant or a combination of other drugs, but it will continue for life. Hence, one should consult with the doctor for the best possible option in this regard. If you want to know the tacrolimus test price, get in touch with the lab or talk to your doctor for an accurate quote. It may vary due to a host of factors.
FAQs
Who will monitor tacrolimus tests?
Tacrolimus is generally monitored by the doctor and transplant team that performed the surgery of a patient. It can also be monitored by a doctor who has specific information about the condition or disease for which it is prescribed.
Why is a tacrolimus blood test done?
A Tacrolimus test is prescribed to detect the level of the tacrolimus drug in the patient’s blood. This test is usually conducted before the patient is put on therapy. This is an immune suppressant medicine usually prescribed before a transplant.
Should a patient tell the other doctors about taking Tacrolimus?
Yes, a patient should surely inform the other doctors about taking Tacrolimus because this is crucial information for them. Other drugs may have interactions and also due to the immunosuppressive action of tacrolimus. This can reduce the ability to heal, tolerate vaccinations, and may up the risk of developing certain cancers such as skin cancers.
What happens if the tacrolimus level is low?
When the tacrolimus level is low it could lead to acute rejection and graft dysfunction in the long run.
What is tacrolimus in the kidney?
Tacrolimus is a medicine that is capable of lowering the body's natural immunity. The response of the immune system is linked to Nephrotic Syndrome. Tacrolimus is extensively used to stop the rejection of transplanted organs, such as the kidney, liver, and heart.
What is the risk of tacrolimus?
The risk from Tacrolimus is that it may lead to acute brain or nerve problems such as posterior reversible encephalopathy syndrome. One should immediately inform the doctor in case of blurred vision, dizziness, headache, confusion, mental changes, high blood pressure, seizures, tiredness, unusual drowsiness, weakness, or a fast heartbeat.
Can tacrolimus cause liver damage?
Tacrolimus therapy is known to cause a mild increase in serum enzymes, and it has also been associated with rare cases of clinically evident cholestatic liver injury.
Why do we check tacrolimus level?
A tacrolimus test is ordered so that the doctors can assess the concentration of the drug in the blood. This helps determine if the level has reached the desired therapeutic range while ensuring it remains below the toxic level.
How long do patients take tacrolimus?
How long will a patient need to take tacrolimus? They will most likely be on this immunosuppressant drug or a similar one to it for as long as the transplanted organ is working properly. However, there may be some changes to the types of immunosuppressants they will take over time.
