What are the Common Lab Tests That Patients Receive After Heart Transplant?

What are the Common Lab Tests That Patients Receive After Heart Transplant?

What are the Common Lab Tests That Patients Receive After Heart Transplant?

As a heart transplant recipient, you’ll quickly find yourself being asked to take a laundry list of blood tests. While this can be inconvenient and frustrating, it’s also really important. Your doctor can’t tell what’s going on with your new heart by looking at you. Blood tests provide information on how well your heart is functioning and how your medications may be affecting your body. By reviewing the results, your physician may adjust medications, recommend changes to your diet or fluid intake, or recognize the need for additional examination.

But what are the specific tests and what is the purpose of each? With the help of Dr. Shelley Hall, Chief of Transplant Cardiology and Mechanical Support/Heart Failure at a large university medical center in the southern US, in this article we discuss:

  • Complete blood count
  • Comprehensive metabolic panel
  • Infection testing
  • Natriuretic peptide test
  • Immunosuppressive drug levels
  • Donor specific antibodies
  • AlloMap® Heart
  • AlloSure® Heart

Complete Blood Count “CBC”

A CBC measures several components of your blood1, including:

  • Red blood cells, which carry oxygen
    • Hemoglobin, the oxygen-carrying protein in red blood cells
    • Hematocrit, the proportion of red blood cells to the fluid component, or plasma, in your blood
  • White blood cells, which fight infection
  • Platelets, which help with blood clotting

For heart transplant recipients, there are a few primary things that physicians look for in a CBC. According to Dr. Hall, “With red cells, your physician is looking at whether you’re anemic or not. With white cells, they are looking for evidence of infection if they are high; or side effects of immunosuppression if they are low. Platelets indicate whether bone marrow may be impacted by immunosuppression or certain infections.”

Comprehensive Metabolic Panel “CMP”

A comprehensive metabolic panel (CMP) is a test that measures 14 different substances in your blood.2 It provides important information about your body’s chemical balance and metabolism. A CMP includes tests for the following:

  • Glucose, a type of sugar and your body’s main source of energy.
  • Calcium, one of the body’s most important minerals. Calcium is essential for proper functioning of your nerves, muscles, and heart.
  • Sodium, potassium, carbon dioxide, and chloride. These are electrolytes, electrically charged minerals that help control the amount of fluids and the balance of acids and bases in your body.
  • Albumin, a protein made in the liver.
  • Total protein, which measures the total amount of protein in the blood.
  • Liver enzymes: ALP (alkaline phosphatase), ALT (alanine transaminase), and AST (aspartate aminotransferase).
  • Bilirubin, a waste product made by the liver.
  • BUN (blood urea nitrogen) and creatinine, waste products removed from your blood by your kidneys.

According to Dr. Hall, transplant cardiologists look at all of these levels and “the CBC and CMP are standard in nearly every appointment for heart transplant patients.”

Infection Testing

Infection testing is less standardized than the tests described above. “Infection testing varies from center to center and region of the country or the world, depending upon what infections are endemic to that particular area,” said Dr. Hall. “Almost every center monitors for cytomegalovirus virus (“CMV”). CMV is a pretty common virus that causes a cold for most healthy people, however it can really wreak havoc with the body of a transplant patient.”

Natriuretic Peptide Test (“BNP”/“NT-proBNP”)

B-type natriuretic peptide (BNP) is a hormone produced by your heart. NT-proBNP is a non-active prohormone that is released from the same molecule that produces BNP. It is released in response to changes in pressure inside the heart. These changes can be related to heart failure and other cardiac problems. According to Dr. Hall, “levels goes up when heart failure develops or gets worse, and levels goes down when heart failure is stable.3”

Immunosuppressive Drug Levels

Immunosuppressive drugs prevent your body from rejecting your new heart. One drug that is frequently prescribed is tacrolimus (others include cyclosporine and sirolimus). Studies show that when patients go below a certain minimum (or “trough”) level of these drugs, they are at increased risk of rejection.4 Therefore “we want to measure levels at the lowest point in the day which is usually early morning before you take your dose to make sure that you are receiving enough medication” said Dr. Hall.

Donor Specific Antibodies (“DSA”)

DSAs are antibodies that you may develop specifically against your new heart. DSA testing allows physicians to monitor the development of these antibodies over time. “Transplant programs have different schedules for DSA testing; at Baylor we check quarterly the first year post-transplant,” said Dr. Hall. “The monitoring is important because, if patients start to develop antibodies that are specific to the heart, they have a higher risk of antibody-mediated rejection.”

AlloMap

The AlloMap Heart test measures the levels of 20 genes in your blood in order to determine if you are at a low risk for rejecting your new heart. According to Dr. Hall, “When AlloMap scores are low, patients’ risk of rejection is very low. This allows physicians to identify patients that may not need invasive biopsies or other invasive types of testing, as long as their scores remain low.”

AlloSure

The AlloSure Heart test measures a biomarker in your blood called donor-derived cell-free DNA (dd-cfDNA). When dd-cfDNA increases, it provides your doctor with an early warning sign that there could be an issue with your heart.

To hear more discussion from Dr. Hall on post-transplant labs and surveillance tools, please see our webinar Post-transplant Surveillance: Making Sure You Get the Most Longevity Out of Your New Heart

Always seek the advice of your physician or medical team with any questions you may have regarding your specific medical condition. The information is not intended or implied to be a substitute for professional medical advice from your healthcare provider.

1 https://www.mayoclinic.org/tests-procedures/complete-blood-count/about/pac-20384919
2 https://medlineplus.gov/lab-tests/comprehensive-metabolic-panel-cmp/
3 https://my.clevelandclinic.org/health/diagnostics/16814-nt-prob-type-natriuretic-peptide-bnp
4 https://pubmed.ncbi.nlm.nih.gov/16013941/

Tags: Health Lifestyle