10 Important Blood Tests: What They Show, Why They're Done, More

Maybe your like

HealthlineSubscribe

Back Pain

Common Blood Tests: Why They're Ordered, Which Require Fasting, and What the Results Mean

Medically reviewed by Kelsey Nank, PA-C — Written by Tim Jewell and Alina Sharon — Updated on April 15, 2025

CBC
Basic metabolic panel
Comprehensive metabolic panel
Lipid panel
Thyroid panel
Cardiac biomarkers
STI screenings
Coagulation panel
DHEA-sulfate serum test
CRP test
Takeaway

Blood tests can help a doctor diagnose a variety of health conditions, including infections, anemia, high cholesterol, vitamin deficiencies, organ failure, HIV, cancer, and diabetes.

Doctors use blood tests to analyze substances like proteins, cells, or chemicals in your blood.

This can give them a picture of your overall health and help them diagnose different diseases, monitor chronic conditions, assess your organ function, and determine your immune system strength.

Regular blood testing is one of the most important ways to keep track of your overall physical well-being. We’ve partnered with Lifeforce to bring you this overview article on blood tests.

Let’s take a closer look at some common blood tests, including why a doctor may recommend them, how to prepare, what they diagnose, and what the results might mean.

Complete blood count (CBC)

A routine complete blood count (CBC) checks for levels of different components in your blood.

Here’s the typical range of results for each component, although every laboratory may have its own range that varies slightly:

Component	Normal range
red blood cells (cells responsible for carrying oxygen throughout the body)	male: 4.5–6.1 × 106/ microleter (μL); female: 4.0–5.4 × 106/μL
white blood cells (immune system cells in the blood)	male: 4.0–10.8 × 103/μLfemale: 4.0–10.8 × 103/μL
platelets (the substances that control the clotting of the blood)	male: 150–400 × 103/μLfemale: 150–400 × 103/μL
hemoglobin (protein within the red blood cells that carries oxygen to organs and tissues and carbon dioxide back to the lungs)	male: 13.0–17.0 grams/deciliter (g/dL); female: 12.0–16.0 g/dL
hematocrit (percentage of blood made of red blood cells)	male: 40–52%; female: 37–47%

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

Basic metabolic panel

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

calcium
glucose
sodium
potassium
bicarbonate
chloride
blood urea nitrogen
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.

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

The Lifeforce Diagnostic is an at-home blood test designed to gather data on 40+ biomarkers that impact your health and longevity, including your metabolic condition, hormone health, and key risk factors for disease. Your diagnostic includes an at-home blood draw from an experienced phlebotomist, a telehealth consultation with a Lifeforce clinician, and a personalized plan that consists of expert insights, lifestyle improvements, nutraceuticals, and hormone and peptide therapies.

Comprehensive metabolic panel

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, this is the main protein in your blood. It’s made in your liver.
total protein, this is the total amount of protein in your blood. It includes albumin and globulins, which are mainly made in your liver.
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

»Learn more:What’s the Difference Between a CMP and BMP?

Lipid panel

This test checks levels of two types of cholesterol:

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

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

HDL cholesterol levels of 60 milligrams per deciliter (mg/dL) or above are considered to be heart-healthy, while under 40 mg/dL is a major risk factor for heart disease. For LDL cholesterol, 100 mg/dL or below is optimal for good health, while 160 mg/dL or over is dangerously high.

Typical levels can also vary by age. A lipid panel also checks for triglycerides.

Thyroid panel

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.

Abnormal levels of these hormones can indicate underactive thyroid (hypothyroidism) or overactive thyroid (hyperthyroidism).

»Learn more:Thyoid Function Tests: Procedure, Side Effect, Results

Cardiac biomarker tests

Common markers include:

High-sensitivity cardiac troponin (hs-cTn):This is a heart protein that is a marker of heart injury.
B-type natriuretic peptide (BNP) and N-terminal pro b-type natriuretic peptide (NT-proBNP): BNP is a hormone that is released when the heart muscle is stretched, generally caused by fluid overload in congestive heart failure.
Creatine kinase (CK): This enzyme is 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.

Sexually transmitted infection tests

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.

Blood tests aren’t always accurate right after contracting an infection. It can take three to six months after exposure to get a positive blood test. This is why it is important to repeat testing.

»Learn more:How Long Does It Take for STD Symptoms to Appear or Be Detected on a Test?

Coagulation panel

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 stop bleeding after a cut or wound. However, 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.

DHEA-sulfate serum test

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 females, high levels can cause typically male traits, like excess body hair, to develop, so low levels are normal.

»Learn more:DHEA-Sulfate Serum Test

C-reactive protein test

C-reactive protein (CRP) is made by your liver when tissues in your body are inflamed.

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

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

Smoking and gingivitis may also be linked with heart disease. More and more evidence suggests a link between oral health and overall inflammation.

The bottom line

Blood tests can offer a good snapshot of your overall health.

They’re also a good way to catch illness or disease early and to see how well your body responds to treatments for various conditions.

Many people get routine blood tests done at least once a year. Talk with your doctor to learn whether there are any other tests you may need to ensure your optimal health.

How we reviewed this article:

SourcesHistoryHealthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

ABIM laboratory test reference ranges ̶ January 2025. (2025).https://www.abim.org/Media/bfijryql/laboratory-reference-ranges.pdf
Adult health maintenance guidelines. (n.d.).https://dchr.dc.gov/sites/default/files/dc/sites/dchr/publication/attachments/Adult%20Health%20Maintenance%20Guidelines_dchr.pdf
American Cancer Society guideline for colorectal cancer screening. (2024).https://www.cancer.org/cancer/types/colon-rectal-cancer/detection-diagnosis-staging/acs-recommendations.html
Basic metabolic panel. (2024).https://medlineplus.gov/lab-tests/basic-metabolic-panel-bmp/
Blood tests. (2022).https://www.nhlbi.nih.gov/health-topics/blood-tests
Cholesterol levels. (2024).https://medlineplus.gov/lab-tests/cholesterol-levels/
Comprehensive metabolic panel (CMP). (2023).https://medlineplus.gov/lab-tests/comprehensive-metabolic-panel-cmp/
DHEA sulfate test. (2024).https://medlineplus.gov/lab-tests/dhea-sulfate-test/
Direct access testing (DAT) and the clinical laboratory improvement amendments (CLIA) regulations. (2019).https://www.cms.gov/regulations-and-guidance/legislation/clia/downloads/directaccesstestingpdf.pdf
Guide to laboratory services: Microbiology. (2023).https://www.azdhs.gov/documents/preparedness/state-laboratory/public-health-microbiology/lab-guide.pdf
Home use tests. (2022).https://www.fda.gov/medical-devices/in-vitro-diagnostics/home-use-tests
How to prepare for a lab test. (2024).https://medlineplus.gov/lab-tests/how-to-prepare-for-a-lab-test/
Lab tests before surgery: when you need them—and when you don’t.https://choosingwiselycanada.org/wp-content/uploads/2017/06/Lab-tests-EN.pdf
LDL and HDL cholesterol: "Bad" and "good" cholesterol. (2024).https://www.cdc.gov/cholesterol/about/ldl-and-hdl-cholesterol-and-triglycerides.html?CDC_AAref_Val=https://www.cdc.gov/cholesterol/ldl_hdl.htm
Menegatti M, et al. (2019). Management of rare acquired bleeding disordershttps://ashpublications.org/hematology/article/2019/1/80/422575/Management-of-rare-acquired-bleeding-disorders
Nehring SM, et al. (2023). C reactive protein.https://www.ncbi.nlm.nih.gov/books/NBK441843/
Prediabetes and type 2 diabetes screening. (2021).https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/screening-for-prediabetes-and-type-2-diabetes
Routine tests during pregnancy. (2023).https://www.acog.org/womens-health/faqs/routine-tests-during-pregnancy
Seo I, et al. (2022). Usefulness of Complete Blood Count (CBC) to assess cardiovascular and metabolic diseases in clinical settings: a comprehensive literature review.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9687310/
STD tests. (2024).https://medlineplus.gov/lab-tests/std-tests/
Tsuruda T, et al. (2019). Non-canonical expression of cardiac troponin-t in neuroendocrine ethmoid sinus carcinoma following immune checkpoint blockade.https://www.frontiersin.org/articles/10.3389/fcvm.2019.00124/full
Understanding your lab test results. (2023).https://www.cancer.org/cancer/diagnosis-staging/tests/understanding-your-lab-test-results.html
What you need to know about blood testing. (2024).https://medlineplus.gov/lab-tests/what-you-need-to-know-about-blood-testing/

Share this article

Medically reviewed by Kelsey Nank, PA-C — Written by Tim Jewell and Alina Sharon — Updated on April 15, 2025

Health Conditions

Condition Spotlight

Wellness Topics

Product Reviews

Featured Programs

Featured

Lessons

Newsletters

Lifestyle Quizzes

Health News

This Just In

Top Reads

Video Series

Find Your Bezzy Community

Follow us on social media