Blood tests can be used to help a doctor identify a variety of health conditions, including vitamin deficiencies, organ failure, HIV, cancer, diabetes, and more.

Regular blood testing is one of the most important ways to keep track of your overall physical well-being. Getting tested at routine intervals can allow you to see the way your body changes over time and empower you to make informed decisions about your health.

Some blood tests can help your doctor determine how different organs in your body are working. Examples of organs whose malfunctions can be visible in a blood test includeTrusted Source your thyroid, liver, or kidneys.

Your doctor can also use blood tests to search for markers of diseases and health conditions such as:

• diabetes
• HIV
• anemia
• cancer
• coronary heart disease

Even if a person does not have heart disease, a blood test can show whether they may be at risk of developing the condition.

Other blood tests can indicate whether the medications you’re taking are working properly, or assess how well your blood is clotting.

Let’s take a closer look at some common blood tests.

A routine complete blood count (CBC) checks for levels of 10 different components of every major cell in your blood: white blood cells, red blood cells, and platelets.

Important components this test measures include red blood cell count, hemoglobin, and hematocrit.

Here’s the typicalTrusted Source range of results, although every laboratory may have its own range that varies slightly:

ComponentNormal rangered blood cells (cells responsible for carrying oxygen throughout the body)male: 4.3–5.9 million/mm3; female: 3.5–5.5 million/mm3white blood cells (immune system cells in the blood)4,500–11,000/mm3platelets (the substances that control the clotting of the blood)150,000–400,000/mm3hemoglobin (protein within the red blood cells that carries oxygen to organs and tissues, and carbon dioxide back to the lungs)male: 13.5–17.5 grams/deciliter (g/dL); female: 12.0–16.0 g/dLhematocrit (percentage of blood made of red blood cells)male: 41–53%; female: 36–46%

Abnormal levels of these components may indicate:Trusted Source

• nutritional deficiencies, such as vitamin B6 or B12
• anemia (iron deficiency)
• clotting problems
• blood cancer
• infection
• immune system disorders

Based on your results, your doctor will order follow-up tests to confirm abnormal levels and a possible diagnosis.

A basic metabolic panel (BMP) usually checks for levels of eight compounds in the blood:

• calcium
• glucose
• sodium
• potassium
• bicarbonate
• chloride
• blood urea nitrogen (BUN)
• creatinine

This test may require you to fast for at least 8 hours before your blood is drawn, depending on the instructions of your doctor and what the test is measuring.

See our chart for normal results.

Abnormal results may indicate:

• kidney disease
• diabetes
• hormone imbalances

Your doctor will perform follow-up tests to confirm a diagnosis.

A comprehensive metabolic panel (CMP) includes all the measurements of a BMP as well as additional proteins and substances related to liver function, such as:

• albumin
• total protein
• alkaline phosphatase (ALP), an enzyme mostly found in the bones and liver that’s involved in several bodily processes
• alanine aminotransferase (ALT), an enzyme found in the liver
• aspartate aminotransferase (AST), an enzyme found in the liver and other tissues within the body
• bilirubin, which is waste resulting from the breakdown of red blood cells that the liver filters out

The same conclusions can be drawn from a CMP as from a BMP for the same substances that a BMP covers. Other abnormal levels can also indicate underlying conditions, such as:

High levelsLow levelsALP• bile duct blockage
• cirrhosis
• gallbladder inflammation
• gallstones
• hepatitis
• Paget’s disease• bone metabolism disorders
• heart surgery
• malnourishment
• zinc deficiencyALT• cirrhosis
• hepatitis
• liver cancer
• liver damageconsidered normalAST• cirrhosis
• heart conditions
• hepatitis
• mononucleosis
• (mono)pancreatitisconsidered normalbilirubin• abnormal red blood cell destruction (hemolysis)
• adverse medication reactions
• bile duct blockage
• Gilbert’s syndrome
• hepatitisnot a concern

This test checks levels of two typesTrusted Source of cholesterol:

• high-density lipoprotein (HDL), or “good” cholesterol
• low-density lipoprotein (LDL), or “bad” cholesterol

HDL is “good” because it removes harmful substances from your blood and helps the liver break them down into waste. LDL is “bad” because it can cause plaque to develop in your arteries, increasing your risk of heart disease.

You may need to fast for at least 8 hours before this test.

Here are the rangesTrusted Source for each type:

HighLow/OptimalHDL>60 mg/dLmale: <40 mg/dL; female: <50 mg/dL (low)LDL>160 mg/dL<100 mg/dL (optimal)

Normal levels can also vary by age.

A thyroid panel, or thyroid function test, checks how well your thyroid is producing and reacting to certain hormones, such as:

• Triiodothyronine (T3). Along with T4, this regulates your heart rate and body temperature.
• Thyroxine (T4). Along with T3, this regulates your metabolism and how you grow.
• Thyroid-stimulating hormone (TSH). This helps regulate the levels of hormones your thyroid releases.

Your thyroid is a tiny gland in your neck. It helps regulate bodily functions like your mood, energy level, and overall metabolism.

Here are normal results:

• T3: 80–180 nanograms per deciliter of blood (ng/dL)
• T4: 0.8–1.8 ng/dL in adults.
• TSH: 0.5–4 milli-international units per liter of blood (mIU/L)

Abnormal levels of these hormones can indicate numerous conditions, such as:

• low protein levels
• thyroid growth disorders
• abnormal levels of testosterone or estrogen

Enzymes are proteins that help your body accomplish certain chemical processes, such as breaking down food and clotting blood. They’re used throughout your body for many vital functions.

Abnormal enzyme levels can indicate many conditions.

Common enzymes tested include:

• Creatine kinase (CK). This is an enzyme primarily located in the brain, heart, and skeletal muscle. When muscle damage happens, CK seeps into the blood in growing amounts.
• Creatine kinase-MB (CK-MB). These enzymes are found in your heart. They often increase in your blood after a heart attack or other heart injury.
• Troponin. This is a heart enzyme that can leak into your blood and results from heart injury.

Here are the normal ranges for the enzyme listed above:

• CK: 30–200 U/L
• CK-MB: 0–12 IU/L
• troponin: <1 ng/mL

Many sexually transmitted infections (STIs) can be diagnosed using a blood sample. These tests are often combined with urine samples or swabs of infected tissue for more accurate diagnoses.

The following STIs can be diagnosed with blood tests:

• chlamydia
• gonorrhea
• herpes
• HIV
• syphilis

Blood tests aren’t always accurate right after contracting an infection. For an HIV infection, for example, you may need to wait at least a month before a blood test can detect the virus.

Coagulation tests measure how well your blood clots and how long it takes for your blood to clot. Examples include the prothrombin time (PT) test and fibrinogen activity test.

Clotting is a crucial process that helps you stop bleeding after a cut or wound. But a clot in a vein or artery can be deadly since it can block blood flow to your brain, heart, or lungs. This can cause a heart attack or stroke.

Coagulation test results vary based on your health and any underlying conditions that may affect clotting.

Results from this test can be used to diagnose:

• leukemia
• excessive bleeding (hemophilia)
• thrombosis
• liver conditions
• vitamin K deficiency

The dehydroepiandrosterone (DHEA) hormone comes from your adrenal glands. This test measures whether it’s too high or too low.

In men, DHEA helps develop traits like body hair growth, so low levels are considered abnormal. In women, high levels can cause typically male traits, like excess body hair, to develop, so low levels are normal.

Low levels may be caused by:

• Addison’s disease
• adrenal dysfunction
• hypopituitarism

High levels in men or women can result from:

• congenital adrenal hyperplasia
• benign or malignant tumor on the adrenal gland
• polycystic ovary syndrome (PCOS)
• ovarian tumor

C-reactive protein (CRP) is made by your liver when tissues in your body are inflamed. High CRP levels indicate inflammation from a variety of causes, including:

• bacterial or viral infection
• autoimmune diseases, such Lupus or rheumatoid arthritis
• inflammation related to diabetes
• inflammation related to physical trauma or from habits like smoking
• cancer

The higherTrusted Source the level, the higher the risk of heart disease:

• <0.3 mg/dL: normal
• 0.3 to 1.0 mg/dL: minor elevation can be associated with a person’s sex, body mass index (BMI), or with conditions like depression or insomnia
• 1.0 to 10.0 mg/dL: moderate elevation usually caused by systemic inflammation, such as from an autoimmune disease, bronchitis, heart attack, or cancer
• >10.0 mg/dL: marked elevation typically caused by a serious bacterial or viral infection, major trauma, or systemic vasculitis
• >50.0 mg/dL: severe elevation usually caused by an acute bacterial infection

If you are showing concerning symptoms of any illness or long-term condition, visit your doctor for a checkup. They will conduct a physical examination and let you know what kinds of blood tests you’ll need to undergo.

If you want to request a routine blood test, the most common ones to consider are:

• complete blood count (CBC)
• basic metabolic panel
• thyroid panel
• nutrient tests for levels of vital nutrients, such as iron or B vitamins

Some other tests you may want include:

• enzyme markers if you’re at risk of cancer or other conditions like cirrhosis, stroke, or celiac disease
• sexually transmitted infection (STI) tests if you recently had sex without a barrier method or had sex with a new partner