How Long to Fast and More

Fasting before certain blood tests is important to help make sure that your test results are accurate.

How do you prepare for a blood test?

Some blood tests will require you to fast beforehand. In these cases, your doctor will instruct you not to eat or drink anything, except water, in the hours leading up to the test.

The vitamins, minerals, fats, carbohydrates, and proteins that make up all food and beverages can impact blood-level readings, clouding the results of your test.

Not all blood tests will require you to fast beforehand. Blood tests that you will likely need to fast for include:

• blood glucose test
• liver function test
• cholesterol test
• triglyceride level test
• high-density lipoprotein (HDL) level test
• low-density lipoprotein (LDL) level test
• basic metabolic panel
• renal function panel
• lipoprotein panel

If your doctor has prescribed a new blood test for you, or doesn’t mention whether or not you should fast or for how long, ask them if fasting is required. Some tests, such as a fecal occult blood test, don’t require fasting but do limit certain foods. Red meats, broccoli, and even some medications may cause a false positive test. Always follow your doctor’s advice when preparing for a test.

The amount of time you need to fast for will vary depending on the test. For most tests, you will be told not to consume anything but water for eight hours leading up to the test. For a few tests, a 12-hour fast may be needed.

Tip

1. Schedule your test as early in the day as possible. The hours you spend sleeping are considered part of the fasting period, as long as you don’t break your fast with coffee or food once you’re awake.

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Even if you drink it black, coffee can interfere with blood test results. That’s because it contains caffeine and soluble plant matter, which might skew your test results.

Coffee is also a diuretic, which means that it will increase how much you pee. This can have a dehydrating effect. The less hydrated you are, the harder it can be for the nurse or other medical professional who’s doing your blood test to find a vein. This can make the blood test harder or more stressful for you.

Some blood tests, such as those that assess liver health or triglyceride levels, may require you to not drink any alcohol for a full 24 hours. Trace amounts of alcohol can remain in your bloodstream for several days. If you have any concerns about alcohol consumption, discuss this with your doctor when you schedule your test.

Also ask your doctor if you can smoke cigarettes before the test, or if you should refrain from smoking during your fast.

It’s fine to drink water before a blood test, unless you’re instructed otherwise by your doctor. This is different from some surgical procedures, which may require you to have a totally empty stomach.

Tap or bottled water are both OK, but leave the squeeze of lemon for another time. Seltzer and club soda are off-limits. Carbonated beverages, flavored or otherwise, shouldn’t be consumed during a fast, and neither should any type of tea.

Tip

1. Water hydrates your body and makes your veins plumper and more visible. Stay hydrated in the two days before your test. Also try drinking several glasses of water right before the blood draw to make it easier for the nurse or other medical professional to find a vein.

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Just like adults, children may need blood tests that require them to fast beforehand. If so, your child’s pediatrician will let you know how long your child should abstain from eating and drinking.

Tips

• Schedule your child’s blood test as early in the day as possible.
• Distract, distract, distract: The hours leading up to the test may be the time to give in and let them watch a nonstop hour of goofy cartoons on TV or play with your iPad.
• Pack a snack for them to devour as soon as the test is done.
• If they manage to sneak a snack when you’re not looking, it’s better to reschedule than to get inaccurate readings.

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There are several blood tests you may need if you’re pregnant. These are designed to assess any potential health concerns that you or your baby might experience during pregnancy or after you give birth. Some of these tests will require you to fast beforehand. Your doctor will advise you how to prepare for each test.

Fasting is usually safe if you’re pregnant, provided you’re in good health and aren’t having a high-risk pregnancy. For your overall comfort, your doctor may advise you to drink extra water or to remain indoors, especially if the weather is very hot or humid.

Fasting may increase heartburn in some pregnant women. If you experience uncomfortable or concerning symptoms of any kind while you’re waiting to have your blood drawn, let your doctor know immediately.

If you’re seeing a doctor other than your obstetrician-gynecologist, make sure they are made aware of your pregnancy before your blood test.

Q:

What happens if you don’t fast before a blood test? Should you still do the test?

Anonymous

A:

If you don’t fast before a test that requires it, the results may not be accurate. If you forget and eat or drink something, call your provider and ask if the test can still be done. Some tests can be analyzed with a notation that it isn’t fasting and results may vary. The main thing is to be honest. If you had a snack, a cup of coffee, or even a full breakfast, tell the technician when you have your blood drawn. They should make a note so that the results are reviewed with the food intake as a variable. And if fasting is an absolute must for meaningful results, they should stop and reschedule your blood draw.

Deborah Weatherspoon, PhD, RN, CRNAAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.

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Basic Metabolic Panel: Procedure, Preparation, and Risks

Whether you’re going to see a doctor for a routine checkup or you’re admitted to the hospital, a basic metabolic panel is a combination of tests that can help a doctor assess important functions in your body.

These tests can be used to identify changes in fluid balance, electrolyte levels, sugar metabolism, and kidney function.

This article will take an in-depth look at a basic metabolic panel, why it’s performed, and what your results may indicate.

Fast facts

• A basic metabolic panel tests levels of eight substances in the blood, which measure electrolyte balance, sugar metabolism, and kidney function.
• Abnormal test results might be used to diagnose kidney disease, diabetes, or lung disease, among other conditions.
• A doctor can provide more information about what your test results mean and whether additional treatment is necessary.

A basic metabolic panel may be part of a routine checkup and also may be used to diagnose certain medical issues, including diabetes and kidney or lung problems.

The tests that make up the basic metabolic panel are blood (serum) tests for:

• BUN (blood urea nitrogen): This measures the amount of nitrogen in the blood in order to determine your kidney function.
• Creatinine: This can tell the doctor how your kidneys are functioning.
• Glucose: This checks your blood sugar levels — abnormally high or low glucose levels could indicate a range of issues.
• CO2 (carbon dioxide or bicarbonate): This references lung and kidney function.
• Calcium: This can help determine if there is a kidney bone or parathyroid problem (a gland in the neck).
• Sodium: This is one of the salts in the body that reflects the body’s water balance.
• Potassium: This is another salt in the body.
• Chloride:This is an electrolyte that helps maintain fluid and acid-base balance.

Your sodium, potassium, and chloride levels will be tested as part of your electrolyte panel. Electrolyte balance is essential to the healthy functioning of the muscular, cardiovascular, and nervous systems.

Below are approximate healthy ranges for each test included in the basic metabolic panel. Depending on the laboratory doing the test, these reference values may vary.

The basic metabolic panel can give doctors a good idea as to whether you have any serious problems with:

• blood filtration
• acid/base balance of your blood
• blood sugar levels
• electrolyte levels

This can help uncover a variety of medical issues, including:

• kidney problems
• lung problems
• problems with insulin metabolism

More detailed tests will be ordered if any of these basic indicators are abnormal.

One advantage of a panel of tests is that many tests can be done with just one blood sample. It’s then divided up in a lab.

A small amount of your blood is needed to perform this panel of tests. The blood sample is obtained through “venipuncture.” A needle is inserted into a vein in your arm or hand. Blood is drawn through the needle into a tube and analyzed in a laboratory.

Sometimes, a doctor might recommend not eating or drinking anything for 8 hours before your test.

Otherwise, you do not need to do anything special before this test and should not stop taking medication unless a doctor tells you to.

When the blood is collected, you may feel some moderate pain or a mild pinching sensation. After the needle is removed, you may feel a throbbing sensation.

You’ll be instructed to apply pressure to the site where the needle entered your skin. A bandage will be applied and may need to remain in place to stop any bleeding. You should avoid using that arm for heavy lifting for the rest of the day.

There are some very rare risks involved in taking a blood sample, including:

• lightheadedness or fainting
• hematoma, a bruise where blood accumulates under the skin
• infection, which is usually prevented if the skin is cleaned before the needle is inserted
• excessive bleeding for a long period after the test may indicate a more serious bleeding condition and should be reported to a doctor

Abnormal test results may indicate a serious medical condition, such as kidney disease, diabetes, or lung disease.

Kidney tests

A high BUN level may indicate kidney disease. Other possible causes include congestive heart failure or hypovolemic shock.

This can increase your BUN, as can bleeding. A low BUN level may be due to insufficient protein in your diet. It may also occur in people who are pregnant or those with a small body type.

A high creatinine level may also be caused by kidney disease, pregnancy, intense physical activity, the use of certain medications, or a diet high in red meat. A low creatinine level may be due to muscle loss, severe liver disease, or a lack of protein in the diet.

Learn more: Kidney health and kidney disease basics »

Sugar metabolism

Fasting blood glucose levels can help to diagnose diabetes. You may have diabetes if your fasting blood glucose is over 126 mg/dL or higher. Other problems, such as hyperthyroidism and certain kinds of pancreatic cancers, involve high blood glucose.

Low blood glucose may indicate an underactive thyroid gland or liver disease. Low glucose can also occur when a person with diabetes consumes too much insulin or other diabetes medications.

Learn more: Understanding borderline diabetes: Signs, symptoms, and more.

Electrolyte panel

High bicarbonate or carbon dioxide levels may be caused by many conditions, including breathing problems, metabolic problems, Cushing’s syndrome, or hormonal problems.

Lower-than-normal levels can be caused by acidosis, kidney disease, or several kinds of poison toxicities.

Learn more: Cushing’s syndrome.

High serum calcium can be caused by problems with the parathyroid gland or certain types of cancer.

Low serum calcium levels can be caused by many conditions, including:

• an underperforming parathyroid gland
• kidney failure or liver disease
• vitamin D deficiency
• problems with your pancreas

High serum sodium may be due to various hormonal diseases, such as diabetes insipidus or Cushing’s syndrome.

A lower-than-normal sodium level may also be due to hormonal abnormalities, such as Addison’s disease or SIADH (syndrome of inappropriate hormone secretion). Low sodium may also be due to dehydration, vomiting, and heart, liver, or kidney failure.

Learn more: Addison’s disease.

High serum potassium often indicates kidney disease and other conditions like Addison’s disease or type 1 diabetes that is not well-controlled. Potassium is very important for muscle function. High potassium levels can cause problems with the electrical activity of the heart.

Low serum potassium may be due to bodily fluids loss, diuretic medications, excessive alcohol use, low dietary potassium intake, or certain hormonal problems. Low levels can cause an irregular heartbeat.

High chloride levels may indicate metabolic acidosis, where the kidneys are not removing enough acid from the body. High chloride levels can also be caused by dehydration or diarrhea, along with other conditions such as kidney disease.

Low chloride levels may be due to Cushing Syndrome, congestive heart failure, or dehydration. Metabolic alkalosis and a number of other abnormalities affect chloride levels as well.

These are all brief summaries of possible causes for abnormal test results. Talk to a doctor about each specific test in detail to learn more about what these levels may indicate.

Here are answers to additional questions about the basic metabolic panel.

What does a metabolic panel test for?

A basic metabolic panel tests levels of eight substances in your blood, including BUN, creatinine, glucose, carbon dioxide, and electrolytes. This can provide information about your body’s fluid balance and the function of your liver and kidneys.

Is fasting required for a basic metabolic panel?

You may sometimes need to avoid eating or drinking anything for at least 8 hours before your test. A doctor can provide more information about whether fasting is required before your test.

What is the difference between a basic and comprehensive metabolic panel?

A comprehensive metabolic panel includes the same eight tests as a basic metabolic panel. However, it also includes six additional tests, which can help assess protein levels and liver function.

A basic metabolic panel can be used to assess your body’s fluid balance and electrolyte levels and diagnose certain medical issues.

Abnormal levels in a basic metabolic panel can be caused by a wide range of health conditions and may indicate an issue with sugar metabolism, kidney disease, or lung problems.

A doctor can provide more details about how to interpret your test results and the best course of treatment to help correct any abnormalities.

What will the blood test tell?

The blood test is of great importance and is one of the most performed clinical tests. It helps to evaluate the work of organs, make an accurate diagnosis, monitor the effectiveness of treatment, and even reveals some types of genetic abnormalities. From this article you will learn what a blood test will tell you, and what varieties of it exist.

Before looking at the types of blood tests, let’s define exactly what doctors can learn from the indicators of this study:

• Assess the person’s overall health.
• Check how well the liver, kidneys, thyroid gland and heart are coping with their functions.
• Find out if the patient has an infection.
• Diagnose diseases such as HIV/AIDS, hepatitis, diabetes, anemia, coronary heart disease.
• Find out if a person is at risk for cardiovascular disease.
• Determine how well the blood coagulates.
• Assess the effectiveness of the prescribed treatment.

In the blood, you can find a huge number of substances that evaluate completely different parameters. We will consider the main ones below.

Generalized (clinical)

This test helps to count the number of blood cells, including red blood cells, white blood cells and platelets. It also allows you to evaluate the indicators of hemoglobin, hematocrit, erythrocyte sedimentation rate.

A complete blood count is used to assess a person’s health status. It is also prescribed if the doctor needs to get information about possible problems. Depending on the parameters of blood cells, a clinical blood test may detect signs of:

• Iron deficiency anemia or B12 deficiency anemia,
• The presence of an infection or inflammatory process in the body,
• Blood cancer,
• Bleeding or bleeding disorders.

At the Persomed clinic, clinical analysis is presented in the Hematological Panel section.

Coagulogram

This test helps to assess the ability of blood to clot and also measures the amount of time it takes for this process. This blood test is prescribed if the doctor suspects a patient has a bleeding disorder. The causes of this phenomenon may be liver disease, thrombophilia (increased clotting) and hemophilia (inability to blood clotting).

On the website of our clinic, the coagulogram is also located in the “Hematological panel” section.

Biochemical blood test

This is one of the most common tests that is prescribed to assess the amount of certain substances in the blood. Thanks to this study, doctors check how well the kidneys, liver, and pancreas are functioning. Also, with the help of blood biochemistry, indicators of fat, protein and carbohydrate metabolism are determined. In general, this analysis allows you to get the most complete picture of what is happening in the patient’s body.

Below are several indicators that are determined by a biochemical blood test:

• Creatinine

Creatinine is produced in skeletal muscles during the breakdown of creatine, a substance that takes part in muscle contraction. It is formed at a constant rate and excreted from the body by the kidneys. That is why, by assessing the amount of creatinine in the blood, doctors determine how efficiently the kidneys are doing their job.

• Urea nitrogen

Blood biochemistry determines the amount of urea nitrogen, providing doctors with important information about kidney and liver function. The liver produces nitrogen in the form of ammonia, which breaks down protein into its constituent amino acids. Nitrogen combines with carbon, hydrogen, and oxygen to form urea, a metabolic waste product. The urea is then transported from the liver to the kidneys, which excrete it in the urine. A blood test determines if the level of urea nitrogen rises above normal. Thus, it is checked whether the work of the liver or kidneys is disturbed.

• Lipid complex

Biochemical analysis of blood allows you to evaluate the patient’s lipid profile. This group of tests includes the measurement of total cholesterol, high-density lipoprotein, low-density lipoprotein, and triglycerides (fats). They determine the risk of developing coronary heart disease.

• Protein

Blood chemistry measures the level of certain proteins. In particular, this test is prescribed to check the level of albumin and total protein in the blood.

Albumin is a protein produced in the liver that performs many functions. Among them is the nutrition of tissues and the transportation of various substances (hormones, vitamins, drugs) throughout the body. If a blood test shows a low level of albumin, this indicates liver damage, kidney disease, malnutrition, or a serious inflammatory process.

Total protein indicates the concentration of globulins, a class of proteins that includes enzymes, antibodies, and hundreds of other proteins. This indicator provides important information about the work of the kidneys and liver.

• Liver tests

When the liver is damaged, it releases enzymes into the bloodstream, and its protein levels begin to drop below normal. A blood chemistry test measures the levels of these enzymes and proteins, which allows the doctor to create a picture of how well the liver is functioning. With the help of this study, hepatitis, cirrhosis and alcoholic liver disease are diagnosed. Learn more about liver tests in this article.

• Blood biochemistry for electrolytes

Electrolytes are electrically charged chemicals (ions) found in the blood and other body fluids. Their concentration depends on the intake of nutrients from food, their absorption in the intestines, as well as the functioning of the kidneys and lungs. The main function of electrolytes is to maintain fluid balance and acid-base balance in the body. Electrolytes include sodium, potassium, chlorides and other substances.

Abnormal electrolyte values ​​may indicate dehydration, kidney or liver disease, heart failure, hypertension, or other conditions.

TORCH infections

The TORCH panel is a group of tests used to diagnose infections that can cause harm to the fetus during pregnancy. The test can detect infections that can cause birth defects in a baby.

The TORCH infection test detects antibodies that are produced by the immune system when an infection enters the body. TORCH is an abbreviation for 5 screening infections:

• Toxoplasmosis ( T oxoplasmosis),
• Other ( O thers) infections, including syphilis,
• Rubella ( R ubella),
• Cytomegalovirus ( C ytomegalovirus),
• Herpes simplex virus ( H erpes simplex virus).

A hepatitis test

Hepatitis virus panel is a test kit used to detect hepatitis A, B, C, and D. This test determines the presence of antibodies or antigens in the blood. Antibodies are proteins that are produced by the body’s immune system to fight harmful substances, or antigens. The latter can act as fungi, viruses, bacteria or parasites. Each antibody recognizes a specific type of antigen.

The hepatitis test is used to:

• Detect hepatitis virus that a person has contracted at the current time or much earlier.
• Determine the chances of a sick person passing the virus on to a healthy person.
• Monitoring the effectiveness of hepatitis treatment.

HIV test

The HIV test performed at our clinic detects the presence of antibodies, proteins produced by the body against HIV infection. From the moment of infection to the production of a sufficient amount of antibodies, it can take from 3 to 12 weeks. For this reason, for an accurate result, it is better to take an HIV test after 3-12 weeks after possible contact with an infected person.

Allergy Tests

The Allergy Panel identifies what is causing your allergy symptoms and helps doctors determine the best treatment. An allergy test detects and measures the amount of allergen-specific antibodies. When a person is in contact with an allergen, our body produces antibodies to fight it. The latter cause the body to release certain chemicals, due to which unpleasant symptoms appear.

Allergy tests detect at least the 10 most common allergic substances. These include dust, pet hair, mites, a mixture of herbs, flowers, and so on. The allergy panel is also useful for identifying food allergens. The latter include nuts, eggs, soybeans, flour, and many other foods.

Persomed Clinic performs both complex allergy panels and tests for antibodies to individual allergens.

A tumor marker blood test

These tests are done to diagnose certain types of cancer or to determine if a person is at risk for developing cancer. Among the most performed tests are:

• Prostate-specific antigen (PSA) – used to diagnose prostate cancer. It can also help detect other problems with the prostate, such as enlargement or inflammation (prostatitis).
• CA-125 protein – used as a marker of ovarian tumor.
• The CA 15-3 tumor marker is used to diagnose breast cancer and to monitor the effectiveness of the prescribed treatment.
• CYFRA 21-1 is a test used to diagnose lung cancer.

Blood sugar test

This indicator reflects the amount of glucose in the blood. It detects hyperglycemia (high sugar levels), hypoglycemia (low sugar levels) and diabetes mellitus.

A thyroid hormone test thyronine (T3). If the thyroid gland produces an increased amount of the hormones T4 and T3, a person is diagnosed with a disorder called hyperthyroidism. If the function of the gland is reduced, this indicates hypothyroidism.

In this article, we have considered only the most performed analyzes. Among the other types of blood diagnostics that are performed at the Persomed clinic, but were not considered in this article:

• Genetic studies,
• Tests that determine the functional state of the hypothalamic-pituitary-adrenal system,
• Immunology and autoimmunology panel,
• Growth factor analysis,
• Cardio-rheumatoid panel,
• Osteoporosis and Anemia Control Panel,
• Prenatal diagnostic panel,
• Reproductive panel,
• Blood test for urogenital infections.

If you need fast and accurate diagnostics according to modern world standards, please contact Persomed. A list of all performed analyzes and diagnostic procedures is presented in the “Services” section. To properly prepare for the analysis, you must call one of the phones at the top of the site in advance. Our administrators will provide all the necessary information and book a time for you.

Sources:

1. Blood Test – General Points, Patient.info,
2. What Are Blood Tests, National Heart, Lung, and Blood Institute (NHLBI),
3. Types of Blood Tests, National Heart, Lung, and Blood Institute (NHLBI),
4. Blood tests, NHS,
5. Coagulation Tests, Healthline,
6. Blood Chemistry Panel, Johns Hopkins Lupus Center,
7. Blood urea nitrogen (BUN) test, MayoClinic,
8. TORCH Panel, University of Rochester Medical Center Rochester,
9. Hepatitis Viral Panel, Healthline,
10. HIV Testing, Centers for Disease Control and Prevention,
11. Blood Testing for Allergies, WebMD,
12. CA 15-3, American Association for Clinical Chemistry,
13. CA 15-3, University of Rochester Medical Center Rochester,
14. Thyroid Function Tests, Patient.info.

blood test

diagnostics

Did you know what you can learn from a blood test? Read more in article

Each of us had a blood test at least once in a lifetime, but what does it show?! In this article, we will consider the general analysis indicators:

1. HEMOGLOBIN (Hb)

The main function of hemoglobin is the function of transporting oxygen from the lungs to tissues and organs, as well as helping to remove carbon dioxide from the body.
Decreased hemoglobin levels may indicate anemia, blood loss, latent internal bleeding, and damage to internal organs.
It can rise with certain types of heart disease, including insufficiency, with blood diseases and even dehydration.

2. ERYTHROCYTES

The level of red blood cells in our blood can be increased both in diseases and in unusual conditions for the body, for example, in mountains at high altitude and with a decrease in oxygen levels.
An increase in red blood cells also indicates diseases such as heart disease (congenital or acquired), diseases of the lungs, kidneys, liver and even bronchi, as well as an excess of steroid hormones in the body, as well as Cushing’s disease or hormone therapy.
The decrease occurs with anemia, acute blood loss, chronic inflammatory processes in the body and in late pregnancy.

3. LEUKOCITES

The main function of these cells is to reduce the level of negative effects on the body.
In total, there are five types of leukocytes (lymphocytes, neutrophils, monocytes, eosinophils, basophils) and each of them performs a specific function.
To determine the ratio of all types of leukocytes, a detailed or extended blood test is required.
A low white blood cell count or leukopenia may indicate the presence of a viral infection (influenza or viral diseases), as well as drug therapy and the use of anticonvulsants or pain medications.

4. PLATELETS

This is an indicator of blood clotting. An excess of the platelet count in the blood is observed in: chronic inflammatory diseases (tuberculosis, ulcerative colitis, cirrhosis of the liver), after operations and treatment with hormonal drugs.
The level of these cells can decrease under the influence of alcohol, heavy metal poisoning, certain blood diseases, kidney failure, diseases of the liver, spleen, and hormonal disorders.