what diseases can be identified through blood sampling?

Routine blood sampling is critical to identifying health problems early, and helping care providers make appropriate treatment interventions.

Why Blood Testing Is Important

In addition to detecting diseases early, blood tests help:

• Make a diagnosis and/or determine stages of a disease (i.e., cancer)
• Identify the risk of developing a disease in the future, including inherited conditions like breast cancer
• Monitor organ function
• Monitor the effectiveness of medication – blood tests indicate concentraion levels of medication in the blood stream, which helps doctors adjust dosage; blood tests can determine how an illness is responding to the prescribed medication
• Monitor the progression of a disease over time
• Prevent disease – high/low levels of certain biomarkers in blood can indicate if an individual needs medical intervention or lifestyle changes to prevent a disease, such as diabetes
• Treat disease

Identifying Diseases Through Blood Testing

In 2020, more people around the world learned that nasal or oral swab testing can reveal an active infection from a virus, such as the novel coronavirus, or SARS-CoV-2. They also learned that blood testing can reveal if a person has developed antibodies against the virus after recovering from COVID-19, the illness caused by SARS-CoV-2.

Blood testing is used to identify other diseases as well.

Cancer: 

If your doctor suspects you have cancer, a series of tests will be ordered, including a blood test. Apart from blood cancer, blood tests alone can’t be used to determine cancer. The tests only show cancerous proteins, cells, or other substances.

Examples of such blood tests include:

• Complete blood count – This blood test determines the number of blood cells in a sample. Blood cancer may be detected using this test because it shows if there are too many or too few of a particular blood cell or the presence of abnormal cells.
• Protein testing – This examines the presence of abnormal immune system proteins often elevated in people with multiple myeloma.

Heart Disease: 

When the heart muscles are damaged, the heart releases certain proteins and substances into the bloodstream. Blood tests are performed to measure the levels of these substances circulating in the blood, and can indicate the extent of the damage.

The most common blood test used to diagnose heart disease is the cholesterol test, which measures the number of fats in the blood and the risk of developing heart disease.

A blood test can also be used to show the triglyceride level, another measure for identifying a patient’s risk of developing heart disease. The normal triglyceride level should be less than 150 mg/dl. Higher levels indicate your body is accumulating more calories than it can burn.

Hepatitis C: 

A blood test is used to determine if a person is infected with the Hepatitis C virus. The test is also known as the HCV antibody test; it looks for Hepatitis C virus antibodies in the blood. Other Hepatitis C tests include the HCV RNA test and the HCV genotype test.

HIV and AIDS: 

Several blood tests are used to test for the AIDS virus. They include:

• Antibody screening test – It tests for the presence of a protein that the body makes 2-8 weeks after HIV infection. It’s called an ELISA test, and is considered to be very accurate.
• Antigen combination test – This blood test detects the virus earlier than the antibody test. It’s used to check for an HIV antigen protein called p24, which develops 2-4 weeks after infection. The test also shows if the body has developed HIV antibodies.
• Nucleic acid test – Also called an RNA test, this is used to look for HIV 10 days after exposure. The doctor prescribes this test if you’ve developed flu-like symptoms or have a high risk of contracting the virus.

How Blood Tests Are Performed

Venipuncture has been the traditional method for performing blood draws, whereby a phlebotomist punctures a vein in your arm to collect tubes of blood that will be sent to the lab for blood tests. However, new blood collection methods, such as the finger-prick method to gather a few drops of capillary blood, have proven effective as alternatives that can provide accurate blood tests results.

The finger-prick technique is designed for dried blood spot testing. This approach is less invasive than venipuncture, doesn't require cold storage or shipping, is cost-effective, and requires only a small blood volume for analysis. This technique, which can be performed with a Mitra^® device, is also known as “capillary blood sample collection” or "volumetric absorptive microsampling (VAMS^®)." The Mitra is a small device with an absorbent tip that is designed to absorb a tiny, precise volume of blood.

The finger-prick blood collection technique applies the dried blood spot, or DBS approach, which involves collecting a small amount of blood (10ul) for analysis as a dried blood sample. Devices like the Mitra microsampler make capillary blood collection easier, because they’re portable and user-friendly.

Note: While fingertip capillary blood collection for dried blood testing can be used to replace many tests that previously relied on wet blood samples, it can’t be used to perform complete blood count, or CBC. This test is used to identify cancerous cells, and still requires a wet blood sample for analysis.

DBS and VAMS samples have proved effective for:

• Biomarkers – Blood biomarkers are used in early screening for many diseases, such as colorectal cancer. DBS-based screening is less invasive and poses minimal discomfort or risk to the patient.
• Comprehensive metabolic panels (CMP) – A group of 14 tests provide information about blood sugar levels, your kidney health, and electrolytes balance. The test determines a patient’s general health status by screening for a variety of conditions, including diabetes, high blood pressure, liver, and kidney disease.
• Enzyme markers – This blood test shows an enzyme’s activity in the body. It detects celiac disease, stroke, cancer, and liver cirrhosis.

Analysis of a Blood Sample

Once a blood sample is collected, it’s sent to lab technicians for processing and analysis to help identify diseases. While some diseases require additional testing information to confirm a diagnosis, blood tests can help identify potential problems early, when treatment or lifestyle changes are likely to be most effective.