Blood tests can be used in a number of ways, such as helping to diagnose a condition, assessing the health of certain organs or screening for some genetic conditions. This page describes some common blood tests. For more information about a wider range of tests, search the blood test A-Z index on Lab Tests Online UK. Cholesterol is a fatty substance mostly created by the liver from the fatty foods in your diet and is vital for the normal functioning of the body. Having a high level of cholesterol can contribute to an increased risk of serious problems such as heart attacks and strokes. Blood cholesterol levels can be measured with a simple blood test. You may be asked not to eat for 12 hours before the test (which usually includes when you're asleep) to ensure that all food is completely digested and won't affect the result, although this isn't always necessary. Find out more about getting tested for high cholesterol and read about cholesterol tests on Lab Tests Online UK. This involves taking a small sample of blood from a vein in your arm and from 1 or more other parts of your body. The samples are combined with nutrients designed to encourage the growth of bacteria. This can help show whether any bacteria are present in your blood. At least 2 samples are usually needed. Read more about blood cultures on Lab Tests Online UK A blood gases sample is taken from an artery, usually at the wrist. It's likely to be painful and is only carried out in hospital. A blood gas test is used to check the balance of oxygen and carbon dioxide in your blood, and the balance of acid and alkali in your blood (the pH balance). A pH imbalance can be caused by: Read more about blood gas tests on Lab Tests Online UK A number of tests can be used to diagnose and monitor diabetes by checking the level of sugar (glucose) in the blood. These include the: Blood glucose test kits may be available to use at home. These only require a small "pin prick" of blood for testing. Read more about glucose tests on Lab Tests Online UK This is done before donating blood or having a blood transfusion, to check what your blood group is. If you are given blood that doesn't match your blood group, your immune system may attack the red blood cells, which can lead to potentially life-threatening complications. Blood typing is also used during pregnancy, as there's a small risk the unborn child may have a different blood group from their mother, which could lead to the mother's immune system attacking her baby's red blood cells. This is known as rhesus disease. If you don't already know your blood type, your blood will be tested at least once during your pregnancy to determine if there's a risk of rhesus disease. Read more about diagnosing rhesus disease. If testing reveals there is a risk of rhesus disease, an injection of a medicine that stops the mother's immune system attacking her baby's blood cells can be given. Read more about preventing rhesus disease. Read more about blood typing on Lab Tests Online UK A number of blood tests can be carried out to help diagnose certain cancers or check if you're at an increased risk of developing a particular type of cancer. These include tests for: This is a test to examine bundles of genetic material called chromosomes. By counting the chromosomes (each cell should have 23 pairs) and checking their shape, it may be possible to detect genetic abnormalities. Chromosome testing can be used: A coagulation test may be used to see if your blood clots in the normal way. If it takes a long time for your blood to clot, it may be a sign of a bleeding disorder such as haemophilia or von Willebrand disease. A type of coagulation test called the international normalised ratio (INR) is used to monitor the dose of anticoagulants, such as warfarin, and check that your dose is correct. Read more about monitoring your anticoagulant dose. Read more on Lab Tests Online UK about coagulation factors and international normalised ratio. This is another test used to help diagnose conditions that cause inflammation. CRP is produced by the liver and if there is a higher concentration of CRP than usual, it's a sign of inflammation in your body. Read more about C-reactive protein on Lab Tests Online UK Electrolytes are minerals found in the body, including sodium, potassium and chloride, which perform jobs such as maintaining a healthy water balance in your body. Changes in the level of electrolytes can have various possible causes, including dehydration, diabetes or certain medicines. Read more about electrolytes on Lab Tests Online UK This test works by measuring how long it takes for red blood cells to fall to the bottom of a test tube. The quicker they fall, the more likely it is there are high levels of inflammation. An ESR is often used to help diagnose conditions associated with inflammation, such as: Along with other tests, an ESR can also be useful in confirming whether you have an infection. Read more about erythrocyte sedimentation rate on Lab Tests Online UK This is a test to check the types and numbers of cells in your blood, including red blood cells, white blood cells and platelets. This can help give an indication of your general health, as well as provide important clues about certain health problems you may have. For example, an FBC may detect signs of: Read more about full blood count on Lab Tests Online UK This involves extracting a sample of DNA from your blood, then searching the sample for a specific genetic change (mutation). Genetic conditions that can be diagnosed this way include: Genetic screening can also be used to check if someone carries a particular gene that increases their risk of developing a genetic condition. For example, if your brother or sister developed a genetic condition in later life, such as Huntington's disease, you may want to find out whether there is a risk that you could also develop the condition. Read more about genetic and genomic testing When the liver is damaged, it releases substances called enzymes into the blood and levels of proteins produced by the liver begin to drop. By measuring the levels of these enzymes and proteins, it's possible to build up a picture of how well the liver is functioning. This can help to diagnose certain liver conditions, including hepatitis, cirrhosis (liver scarring), and alcohol-related liver disease. Read more about liver function tests on Lab Tests Online UK This test is used to test your blood for levels of thyroid-stimulating hormone (TSH), and, where needed, thyroxine and triiodothyronine (thyroid hormones). If you have low or high levels of these hormones, it could mean you have a thyroid condition such as an underactive thyroid or overactive thyroid. Read more about thyroid function tests on Lab Tests Online UK
Page last reviewed: 08 August 2022 We include products we think are useful for our readers. If you buy through links on this page, we may earn a small commission. Here’s our process. C-reactive protein (CRP) is a substance the liver produces in response to inflammation. A high level of CRP in the blood can be a marker of inflammation. A wide variety of conditions can cause it, from an infection to cancer. High CRP levels can also indicate that there’s inflammation in the arteries of the heart, which can mean a higher risk of heart attack. However, the CRP test is an extremely nonspecific test. CRP levels can be elevated in many inflammatory conditions. If your doctor suspects you may have an inflammatory disorder (like arthritis, cancer, an infection, etc.), they may order a C-reaction protein test. This test can show there’s a high level of inflammation, but it does not show where the inflammation is located or what might be causing it. If you have a previously diagnosed inflammatory issue, your doctor may also order this test occasionally to see how your treatment is working, and if the issue is being properly managed. It’s important to note that ahigh-sensitivity C-reactive protein (hs-CRP) test is a slightly different test than a regular C-reaction protein test. This test typically predicts heart disease and stroke. While the regular C-reactive test can help uncover different diseases that cause inflammation by measuring high levels of protein, the hs-CRP test measures lower (but still elevated) levels of protein, which can signal the risk of heart disease and stroke. Your doctor may order a hs-CRP if they’re focusing on cardiovascular issues. CRP and heart diseaseExpert opinion from the American Heart Association in 2019 states that when considering all risk factors, people with CRP levels greater than or equal to 2 milligrams per liter (mg/L) may need more intense measures to prevent cardiovascular disease. Elevated levels of CRP may have an important role in identifying people who might need closer follow-up or more intensive treatment after heart attacks or heart procedures. CRP levels may also be useful in identifying people at risk of heart disease when cholesterol levels alone may not be helpful. The Centers for Disease Control and Prevention (CDC) considers the following as significant risk factors for developing heart disease: A family history of heart disease can also put you at a higher risk of heart disease. No special preparation is necessary for this test. You may eat normally on the day of, and the test can happen at any time of day. This test is done via a blood sample, so there will be a small needle involved. A nurse or other healthcare professional will draw blood from a vein, usually on the inside of your elbow or the back of your hand. First, they clean the skin over the vein with antiseptic. Next, they wrap an elastic band around your arm, causing your veins to bulge out slightly. The healthcare professional then inserts a small needle into the vein and collects your blood in a sterile vial. After the healthcare professional collects your blood sample, they remove the elastic band around your arm and ask you to apply pressure to the puncture site with gauze. They may use tape or a bandage to hold the gauze in place. Are there risks with the test?There are no risks associated with this test other than routine issues that can occur with any blood test. The main issues include:
If you’re nervous around needles or blood, talk with the healthcare professional administering the test about ways to make it more comfortable for you. In general, the results of your test will be measured in either mg/dL or mg/L. Your doctor will most likely explain the results of your test to you, but in general:
According to a 2003 study by the American Heart Association, people with a higher level of CRP were two to three times more likely to have a heart attack than people with lower levels of CRP. A small study from 2013 evaluated 100 people with cardiovascular risk factors. Researchers found that a CRP level over 10 mg/L was connected to a 4 percent risk of developing a fatal cardiovascular disease in 10 years. If your doctor believes you may be at risk of heart disease or stroke, they may order a hs-CRP blood test alongside other tests. Additionally, there’s more recent research that suggests CRP may be used as a predictor of health outcomes related to chronic obstructive pulmonary disease (COPD). If your doctor is concerned you are dealing with the symptoms of other inflammatory conditions besides cardiovascular issues, they may order a regular CRP test to diagnose, among other things:
Lowering your CRP isn’t a guaranteed way to lower your risk of cardiovascular or autoimmune disease. It’s important to know that high CRP is what doctors call a biomarker. A biomarker is a factor to keep in mind when analyzing a person’s health, but not a stand-alone indicator of a particular diagnosis. A 2015 study indicates that eating a nutritious, balanced diet — including lots of fruits, vegetables, and fiber — may help lower your CRP concentration. If you’re at high risk of cardiovascular disease and your test results show high CRP, your doctor may suggest a statin or other cholesterol-lowering medication. Vitamin C has also been explored as a way to lower CRP levels for people who have an elevated risk of cardiovascular disease. A 2017 research review suggests that probiotics may also have a positive effect in lowering CRP. However, more studies have to be done for each method before any definitive claims can be made. C-reactive protein (CRP) is a substance the liver produces in response to inflammation. If your doctor suspects you may have a high level of inflammation, they may order a CRP blood test as one way to identify the underlying cause of that inflammation. While a CRP blood test can’t say what exactly is causing your inflammation, your doctor may be able to use it to help them diagnose your issue. Sometimes a high CRP measurement can be a risk factor for cardiovascular disease. If you’ve recently noticed changes in your body that aren’t going away and causing you discomfort, talk with your doctor about your symptoms. A CRP blood test may be one of the tests your doctor decides to order. |