Complete Blood Count (CBC)
A comprehensive blood test that measures red blood cells, white blood cells, and platelets to assess overall health, detect infections, and screen for blood disorders like anemia.
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LevelPanel has no business or affiliate relationship with Quest or LabCorp. These links are provided as a public service.
Lab testing services linked from this site are not available to residents of Alaska, Arizona, or Hawaii, unless otherwise noted on the lab's own website.
This publication is not intended to solicit the purchase of laboratory testing from any individual consumer.
What this test measures
A Complete Blood Count (CBC) is one of the most frequently ordered blood tests, and for good reason: it delivers a detailed snapshot of the three major cell types circulating in the bloodstream. The test quantifies red blood cells (which carry oxygen to tissues), white blood cells (which defend against infection), and platelets (which help stop bleeding by forming clots). It also reports hemoglobin concentration, hematocrit (the proportion of blood volume occupied by red cells), and red blood cell indices that describe the average size and hemoglobin load of each red cell.
A white blood cell differential, which breaks down the various subtypes of immune cells, is typically included as well. Healthcare providers rely on the CBC to screen for a wide range of conditions, from anemia and clotting disorders to infections and certain cancers. The test is a standard part of routine physicals and is also ordered when someone presents with unexplained fatigue, persistent weakness, fever, or unusual bruising, all of which can point to an underlying issue with blood cell production or function.
What's included
Who should consider this test
You might consider this test if you are experiencing any of the following:
- Individuals experiencing persistent fatigue, weakness, or unexplained tiredness that may indicate anemia or other blood disorders
- Those with symptoms of infection such as fever, chills, or swollen lymph nodes that warrant immune system evaluation
- People with unusual bleeding, frequent bruising, or prolonged bleeding that could suggest platelet or clotting abnormalities
- Individuals undergoing routine health screenings or annual physical examinations as part of preventive healthcare
- Those with chronic medical conditions requiring ongoing monitoring of blood cell counts and overall health status
- People taking medications that may affect blood cell production or function, requiring regular monitoring for side effects
What to expect
Preparation
No special preparation is typically required for a CBC test. Patients can eat and drink normally before the test unless other blood tests requiring fasting are being performed simultaneously. Individuals should inform their healthcare provider about all medications and supplements they are taking, as some may affect test results.
Sample Type
Blood sample collected through a simple blood draw from a vein in the arm
Collection
A nurse or lab technician will take a sample of blood by putting a needle into a vein in the arm. The procedure takes just a few minutes and involves minimal discomfort. A CBC is a safe, common test with very low risk of complications.
Turnaround
Results are typically available within 24-48 hours after the blood sample is collected and sent to the laboratory for analysis
Understanding your results
CBC results are evaluated against reference ranges that differ based on sex and age, so two people with identical numbers may receive different clinical interpretations. A value that falls outside the reference range does not automatically signal a problem; healthcare providers weigh CBC findings alongside symptoms, medical history, and additional test results before drawing conclusions.
It is also worth noting that reference ranges can vary slightly from one laboratory to another. A single out-of-range result may prompt a repeat test rather than immediate intervention, because trends over time tend to be more clinically meaningful than any isolated reading.
| Population | Reference Range | Notes |
|---|---|---|
| Adult Males | RBC: 4.5-5.9 million cells/mcL, Hemoglobin: 13-18 g/dL, Hematocrit: 41.5-50.4%, WBC: 4,000-11,000 cells/mcL, Platelets: 150,000-400,000/mcL | Reference ranges for healthy adult males based on typical laboratory standards |
| Adult Females | RBC: 4.1-5.1 million cells/mcL, Hemoglobin: 12-16 g/dL, Hematocrit: 35.9-44.6%, WBC: 4,000-11,000 cells/mcL, Platelets: 150,000-400,000/mcL | Reference ranges for healthy adult females, with slightly lower red cell values due to physiological differences |
| Children | Varies significantly by age | Pediatric reference ranges differ from adult values and change throughout childhood development |
Reference ranges shown are general guidelines. Your lab report will include the specific reference range used by the laboratory that processed your sample, which is the authoritative range for interpreting your results.
What does a “Low” result mean?
Low red blood cell counts (anemia) may be caused by nutritional deficiencies (like B12 deficiency or iron deficiency), blood loss/bleeding, low kidney function and blood and bone marrow disorders. Low white blood counts may be caused by autoimmune diseases, medications, bone marrow disorders and infections. Low platelet counts may be caused by immune thrombocytopenia, certain cancers and hemolytic uremic syndrome. Diet, activity level, medicines, having a menstrual period, not drinking enough water, and other factors can affect the results. If any levels are abnormal, it doesn't always mean there is a medical condition that needs treatment. Low results may be temporary and resolve on their own, particularly if they are only slightly below normal ranges or are related to recent illness or lifestyle factors.
What does a “High” result mean?
High white blood counts may be caused by infections, allergic conditions, autoimmune conditions, lymphoma and leukemia. Elevated red blood cell counts, hemoglobin, or hematocrit may indicate dehydration, lung disease, or in rare cases, blood disorders like polycythemia. High platelet counts may be caused by infections and immune system issues. High platelet count (thrombocytosis) is defined as more than 450,000 platelets per microliter. Elevated results don't always indicate serious conditions and may be temporary responses to illness, stress, or other factors. It's important to note that high values can sometimes be related to lifestyle factors, medications, or temporary conditions. Healthcare providers typically recommend additional testing or monitoring when results are significantly elevated to determine the underlying cause and appropriate next steps.
Privacy & confidentiality
All test orders are authorized and results reviewed by an independent, board-certified physician who is not the patient's personal doctor. At LevelPanel, patient privacy and confidentiality are our highest priorities. All CBC test results are handled with strict confidentiality protocols and are <u>not reported to your doctor</u> unless you specifically choose to share them. Your test results are <u>not part of your medical records</u> and will not appear in your permanent healthcare file without your explicit consent. Your CBC test results are also <u>not on insurance statements</u> or Explanation of Benefits (EOB) forms, ensuring complete privacy from insurance companies and employers. We use secure, HIPAA-compliant systems to protect your personal health information, and only you have access to your results through our secure patient portal. No doctor visit required to order this test, giving you complete control over your health information and testing decisions. We never share your test results with third parties, employers, or government agencies without your written authorization. Your privacy is protected by federal law, and we go above and beyond these requirements to ensure your health information remains completely confidential and under your control.
Frequently asked questions
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Read ArticleLast reviewed: April 10, 2026
CPT Code: 85025
This test may not be available in: NY, NJ, RI
This page is for informational purposes only and does not constitute medical advice. Always consult with a healthcare provider regarding any health concerns. LevelPanel does not diagnose, treat, or prescribe.
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LevelPanel has no business or affiliate relationship with Quest or LabCorp. These links are provided as a public service.
Lab testing services linked from this site are not available to residents of Alaska, Arizona, or Hawaii, unless otherwise noted on the lab's own website.
This publication is not intended to solicit the purchase of laboratory testing from any individual consumer.
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