Guide To Common Blood Tests

September 9, 2023

Blood tests are performed to measure the levels of certain substances in the blood and detect disease. The tests involve taking a sample of blood from the patient. In most cases, a nurse or phlebotomist will perform them. The entire procedure takes around three minutes to complete. After cleaning the skin, the technician places a needle into a vein in the patient's arm or hand to withdraw the sample. Certain blood tests can also be completed using a fingerstick method. A laboratory analyzes the sample, and the patient is typically informed of the results within a week.

Some patients may request a prescription topical numbing cream that can be applied to the skin a few hours before the blood test to make it more comfortable. Using cold spray can help minimize pain as well. Blood tests before surgery and in emergency settings are common. Routine checkups include blood tests to diagnose many conditions. Blood tests are often the first step in devising an effective treatment plan. For instance, they may reveal a nutritional deficiency that requires supplements, such as iron or vitamin B12 supplements. Of course, it is vital for patients to understand the common blood tests and their function.

Complete Blood Count

A complete blood count measures the patient's levels of ten different parts that make up whole blood. These parts include the white blood cells, red blood cells, platelets, hemoglobin, and hematocrit. Complete blood counts are used to check if the body is making a healthy number of each of these cells. They can help doctors identify dehydration, infection, internal bleeding, and blood clotting issues. This type of blood test is also used to detect nutritional deficiencies, including in iron and B vitamins. The results can assist doctors in evaluating the patient for potential bone marrow problems, heart conditions, and cancers. If abnormalities are discovered, patients may need additional blood tests or imaging studies to determine the underlying cause.

Tests For Vitamin Levels

Blood tests for vitamin levels may be ordered as part of a routine physical examination or for patients exhibiting symptoms such as fatigue. For example, many patients now have their vitamin D levels checked as part of the bloodwork ordered during annual checkups. Tests for vitamin levels are done with a blood sample taken from a vein. If the results show the patient is low in a particular vitamin, doctors will normally prescribe high-dose supplements for a few weeks or months. The patient will be given another blood test after that time to check if their levels are within the normal range. In cases where vitamin levels are extremely low, doctors may give a series of vitamin injections; this is especially common in the case of vitamin B deficiencies.

Basic Metabolic Panel

Doctors typically order a basic metabolic panel to check for conditions such as hormonal imbalances, kidney disease, diabetes, and lung issues. Patients having this blood test will need to fast for at least eight hours before their appointment. The basic metabolic panel measures a patient's calcium, glucose, sodium, potassium, and electrolytes. It also checks for the amount of carbon dioxide, chloride, blood urea nitrogen, and creatinine. High levels of blood urea nitrogen (BUN) could indicate kidney failure or congestive heart failure, and low levels may be signs of insufficient dietary protein or liver issues. High creatinine levels could be potential indicators of preeclampsia or diseases that affect the muscles, and abnormally low levels may indicate muscular dystrophy. Patients following a low protein diet typically display low albumin readings. These may also occur as a result of recent bariatric surgery. High calcium levels are associated with cancer, and low calcium could signal issues with the pancreas. Low sodium measurements from a basic metabolic panel are often caused by dehydration or vomiting. They may also be present in cases of Addison's disease.

If abnormalities are found on a basic metabolic panel, doctors will normally order a complete metabolic panel and other tests to determine the underlying cause. This metabolic panel can provide more information about any potential liver issues a patient might be experiencing. Patients who have endocrine disorders may need to have metabolic panels performed fairly regularly to monitor their condition.

Thyroid Panel

Also known as a thyroid function test, a thyroid panel helps doctors understand how well a patient's thyroid is manufacturing and responding to particular hormones. The thyroid is a gland in the neck involved in regulating metabolism, mood, and energy. This test is often ordered if a patient is experiencing symptoms that could indicate a thyroid issue. These symptoms include weight gain, fatigue, mood swings, and feeling cold. Levels of triiodothyronine (T3), thyroxine (T4), T3 resin uptake (RU), and thyroid-stimulating hormone (TSH) are all measured as part of a thyroid panel. The first two regulate body temperature, heart rate, metabolism, and growth. Thyroid-stimulating hormone controls the quantities of hormones released by the thyroid. T3 resin uptake is a measure of how well a hormone known as thyroxine-binding globulin is performing.

Thyroid panel results outside of the normal range could indicate a patient has a thyroid growth disorder or low protein. They may also have abnormal levels of testosterone or estrogen. Patients who have abnormal results on a thyroid test are typically referred for a thyroid uptake test and an ultrasound of the thyroid gland. Issues involving an overactive or underactive thyroid can normally be treated with medication.

Lipid Panel

A lipid panel is performed to measure a patient's cholesterol. Specifically, the test measures high-density lipoprotein ('good') and low-density lipoprotein ('bad') cholesterol. This test is ordered as part of annual checkups. Patients who take medication to treat high cholesterol have it performed periodically to monitor the effectiveness of their medication. Individuals having a lipid panel performed will need to fast for at least eight hours before the test.

Normal high-density lipoprotein cholesterol levels are less than sixty mg/dL. Normal values for low-density lipoprotein cholesterol are less than 160mg/dL. Doctors use the results from lipid panels to guide their treatment recommendations. For example, patients with mildly elevated lipids might be encouraged to try dietary changes. They may also be prescribed a statin. Patients with severely elevated levels may need to take multiple medications to keep their cholesterol under control.

Blood Sugar Test

Blood sugar tests are prevalent. In healthy individuals, they can be part of a routine health checkup to determine if their exercise routine or diet needs to change in any way. Blood sugar tests are also a major part of diagnosing and treating various forms of diabetes. This is because, as is evident by the name, this blood test measures the patient’s glucose (blood sugar). Individuals may have diabetes if a random blood sugar test returns a result of two hundred milligrams per deciliter or higher.

Diabetes patients will often have home blood sugar tests to monitor their condition. However, they usually must have fasting blood glucose tests at some doctor’s appointments as well. The exact schedule for this depends on their specific condition. Their primary doctor will discuss it with them.

Blood Enzyme Test

Enzymes are critical in an individual’s body. Digestive enzymes, for instance, work with stomach acid to break down food in the stomach. Other enzymes are crucial for proper blood clotting. Every organ and cell contains enzymes. This is a significant reason why blood enzyme tests, also called enzyme markers, are so common. These tests look at enzyme activity in specific parts of the body to see if the enzymes are working correctly.

Many diseases cause issues with enzyme activity in the body. In many cases, they cause enzymes to stop working. Doctors often order multiple blood enzyme tests, as monitoring the change in enzymes is a useful diagnostic method for many conditions. An incredibly common blood enzyme test is a cardiac enzyme test. Doctors use this most often in an emergency setting when they believe that a patient is having a heart attack.

Coagulation Panel

Many individuals will have a few coagulation panels throughout their lifetime. A coagulation panel, which is also referred to as a coagulation test, measures how well an individual’s blood can clot and how long it takes. This type of blood test helps doctors assess a patient’s risk of blood clots as well as excessive bleeding. Doctors use coagulation panels to diagnose blood disorders, including hemophilia and thrombophilia. These tests are also standard in patients who are on medications that affect their blood’s ability to clot, such as warfarin, heparin, and vasopressin. Many patients will need a coagulation panel done prior to surgery.

C-reactive Protein Test

Individuals will typically receive a C-reactive protein test when their doctor is checking for an infection or another medical condition that causes inflammation. These medical conditions include lupus and rheumatoid arthritis. The reason is that individuals with inflammation will have elevated levels of C-reactive protein in their blood. Doctors will order a high-sensitivity C-reactive protein test for some individuals. They use this version of the test to measure a patient’s risk of coronary artery disease. This condition, which involves narrow arteries in the heart, can result in a heart attack.

Pregnancy Blood Test

The majority of women use home pregnancy tests, which involve urinating on a stick, to find out whether or not they are pregnant. Although this can work, the most accurate test is a pregnancy blood test. When women make an appointment after a positive result on a home test, their doctor will often recommend a blood test to confirm the results. A pregnancy blood test measures the amount of human chorionic gonadotropin in a woman’s blood. This hormone is one that women secrete during pregnancy. Thus, a positive pregnancy blood test means that the woman’s human chorionic gonadotropin levels are elevated. Doctors may also order one of these tests if they suspect a high-risk pregnancy, multiple babies, or other issues. These tests are also used to detect a miscarriage, ectopic pregnancy, and other significant complications.

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