A CBC with differential is a routine blood test that counts your red blood cells, white blood cells and platelets, then breaks your white cells down into their five types: neutrophils, lymphocytes, monocytes, eosinophils and basophils. When the order says "CBC with automated diff," it means an analyzer did that breakdown instead of a technologist counting cells under a microscope. It needs no fasting, and the complete blood count with differential costs $24 all-in through JustLabs.
What Does a CBC with Differential Measure?
Here is every number on a typical Quest CBC with differential report. The ranges are the Quest reference ranges printed on reports and used by JustLabs to flag results. Ranges vary by lab, age and sex, so always compare your values with the range printed on your own report.
| Component | What it measures | Quest reference range (adults) |
|---|---|---|
| WBC (white blood cell count) | Total white cells, your infection-fighting cells | 3.8-10.8 Thousand/uL |
| Neutrophils (absolute) | First responders to bacterial infection and inflammation | 1500-7800 cells/uL |
| Lymphocytes (absolute) | T, B and NK cells; respond to viruses and drive immune memory | 850-3900 cells/uL |
| Monocytes (absolute) | Clean-up cells that become macrophages in tissue | 200-950 cells/uL |
| Eosinophils (absolute) | React in allergies, asthma and parasitic infections | 15-500 cells/uL |
| Basophils (absolute) | Release histamine in allergic reactions | 0-200 cells/uL |
| RBC (red blood cell count) | Number of oxygen-carrying red cells | Men 4.20-5.80 M/uL; women 3.80-5.10 M/uL |
| Hemoglobin | Oxygen-carrying protein inside red cells | Men 13.2-17.1 g/dL; women 11.7-15.5 g/dL |
| Hematocrit | Share of blood volume made up of red cells | Men 38.5-50.0%; women 35.0-45.0% |
| MCV | Average red cell size | 80.0-100.0 fL |
| MCH | Average amount of hemoglobin per red cell | 27.0-33.0 pg |
| MCHC | Hemoglobin concentration inside red cells | 32.0-36.0 g/dL |
| RDW | How much red cells vary in size | 11.0-15.0% |
| Platelets | Cell fragments that form clots | 140-400 Thousand/uL |
| MPV (on some reports) | Average platelet size | 7.5-12.5 fL |
Your report also lists each white cell type as a percentage of the total. The percentages always add up to 100, so a percentage can look high only because another cell type is low. The absolute counts (the total WBC multiplied by each percentage) are what clinicians usually go by, and they are the values the ranges above apply to.
CBC vs CBC with Differential: What's the Difference?
A plain CBC reports the total white cell count but not which kinds of white cells you have. The differential adds that breakdown. It matters because two people can both have a WBC of 12 Thousand/uL for very different reasons: one has extra neutrophils from a bacterial infection, the other has extra lymphocytes from a viral illness. A raised total tells you something is going on; the differential points toward what.
At Quest, the standard order is the CBC (includes differential and platelets), so you get the five-part breakdown by default. That is the test JustLabs offers.
What Is a CBC with Automated Diff?
"Automated diff" describes how the white cell breakdown was done:
| Automated differential | Manual differential | |
|---|---|---|
| Who counts | A hematology analyzer | A lab technologist with a microscope |
| How | Classifies cells by size, internal structure and staining using flow cytometry, impedance or light scatter | Reads a stained blood smear slide cell by cell |
| Cells counted | Far more cells per sample | A fixed count; the reference method counts 200 white cells |
| Strength | Fast, precise and consistent for normal-looking samples | Sees cell shape (morphology) and abnormal or immature cells an analyzer can only flag |
| When used | Routine first pass for almost every CBC | When the analyzer flags the sample or results meet lab review rules |
Automated analyzers count far more cells than a person can, which makes the percentages statistically steadier. A manual count is the traditional reference: the microscopic count of 200 white cells that analyzers are calibrated against. According to diagnostic hematology research, automated methods offer good precision and reproducibility for most patient samples.
The two methods work together. When the analyzer sees something it cannot classify, such as possible immature cells, blasts or atypical lymphocytes, it flags the sample and a technologist reviews a smear. An international consensus group of hematology experts published a set of 41 rules labs can use to decide when an automated result needs that manual follow-up. Even with newer digital imaging systems, an ICSH review concluded that a skilled morphologist remains essential to interpret the blood smear. The MercyOne diagnostic flowchart is one example of how a lab decides when a flagged sample needs manual review.
You do not choose between the two. You order a CBC with differential, and the lab decides whether a manual review is needed.
What High and Low Results Can Suggest
The patterns below are educational, not a diagnosis. A single value slightly outside the range is common in healthy people, and the meaning depends on your symptoms, history and the rest of the report.
White blood cells
| Result | Common associations |
|---|---|
| High WBC with high neutrophils | Bacterial infection, inflammation, physical or emotional stress, smoking, corticosteroids |
| High lymphocytes | Viral illness (especially in children), some chronic infections |
| High eosinophils | Allergies, asthma, eczema, parasitic infection |
| High monocytes | Recovery from infection, chronic inflammatory conditions |
| High basophils | Allergic reactions; less often, bone marrow disorders |
| Low WBC or low neutrophils | Some medications, viral infections, autoimmune conditions, bone marrow problems; some healthy people naturally run low |
| Low lymphocytes | Acute stress, corticosteroids, some infections and immune conditions |
A review in American Family Physician notes that leukocytosis (a high white count) is a common sign of infection, particularly bacterial, and that the white count can double within hours after stimuli such as surgery, exercise, trauma or emotional stress. The same review lists smoking, obesity, certain medications and chronic inflammatory conditions as non-cancer causes. Corticosteroids are a classic example: they typically raise neutrophils and lower lymphocytes and eosinophils.
Red blood cells and indices
Hemoglobin and hematocrit below range mean anemia. The red cell indices then help sort out the type:
- Low MCV (small cells): most often iron deficiency; thalassemia trait is another cause
- High MCV (large cells): vitamin B12 or folate deficiency, alcohol use, some medications, liver or thyroid issues
- Normal MCV: blood loss, anemia of chronic disease, kidney disease, or an early or mixed picture
- High RDW: a mix of cell sizes, which can show up early in iron deficiency or when two causes overlap
High hemoglobin, hematocrit or RBC most often reflects dehydration (less water in the blood concentrates the cells), smoking or living at high altitude; less commonly, lung or heart disease or a bone marrow condition called polycythemia. A review of anemia testing notes that the CBC with red cell indices offers clues to diagnosis and that a reticulocyte count is a useful screen for hemolysis or blood loss.
Platelets
Thrombocytopenia is defined as a platelet count below 150 × 10³ per µL (note that the Quest range starts at 140). People with platelet counts above 50 × 10³ per µL rarely have symptoms. Low platelets can come from medications, infections, liver disease, immune conditions, pregnancy or bone marrow problems, and sometimes from platelets clumping in the tube (pseudothrombocytopenia), which a repeat draw can clear up. High platelets (thrombocytosis) are usually reactive, for example to inflammation, infection or iron deficiency. If you take aspirin or another blood thinner, see how it can affect platelet and clotting tests.
Patterns across the whole report
| Pattern | Hgb/Hct | MCV | WBC | Platelets |
|---|---|---|---|---|
| Iron deficiency | Low | Low | Normal | Normal or high |
| B12 or folate deficiency | Low | High | Normal or low | Normal or low |
| Bacterial infection | Normal | Normal | High (neutrophils up) | Normal or high |
| Viral infection | Normal | Normal | Normal or high (lymphocytes up), sometimes low | Normal or low |
| Dehydration | High | Normal | Normal or high | Normal or high |
Values that are far out of range, such as hemoglobin under 7 g/dL, a platelet count under 50,000/µL, or any report that mentions blasts, need prompt medical attention. Changes in more than one cell line at once (for example, low red cells, low white cells and low platelets together) also deserve a clinician's review.
Can a CBC with Differential Detect Cancer?
A CBC cannot diagnose cancer, but it is often the first test to show that something in the bone marrow needs a closer look. Leukemias and some lymphomas can cause very high or very low white counts, unusual cell distributions or immature cells, which the analyzer flags for manual review. The American Family Physician leukocytosis review lists fever, weight loss, bruising and fatigue as symptoms that suggest a blood cancer, and recommends referral to a hematologist/oncologist when malignancy cannot be excluded. Most abnormal CBCs, however, have common, non-cancer explanations.
When Is a CBC with Differential Ordered?
Clinicians order it as part of routine checkups and to look into symptoms such as:
- Fatigue, weakness, pale skin or shortness of breath (possible anemia)
- Frequent, severe or slow-to-clear infections
- Easy bruising, nosebleeds or bleeding gums (possible low platelets)
- Unexplained fever, night sweats or weight loss
- Swollen lymph nodes
It is also used to monitor conditions and medications that affect the bone marrow or blood counts, before surgery, and during pregnancy. The University of Iowa clinical laboratory describes it as a frontline screening tool for blood disorders. If you have no symptoms, a baseline result is useful for comparison later, since trends over time often say more than a single value.
How to Prepare for a CBC with Differential
- No fasting is required. The CBC is not a fasting test, so you can eat and drink normally.
- One nuance: a study of healthy volunteers found that a light meal produced measurable shifts in several values, including lymphocytes, neutrophils and hemoglobin, in the hours afterward. That rarely matters for a single test, but if you are tracking your counts over time, testing under similar conditions each time makes results easier to compare.
- If your order includes fasting tests, such as a lipid panel or fasting glucose, follow the fasting instructions for those.
- Drink water as usual. Dehydration concentrates the blood and can push hemoglobin, hematocrit and RBC up.
- Skip hard exercise right before the draw, since strenuous exercise can briefly raise the white count.
- Note recent illness, transfusions, pregnancy and medications (especially steroids, chemotherapy and antibiotics) when you review results, because they change counts.
The sample is a standard blood draw from an arm vein into a lavender-top EDTA tube, which keeps cells intact and stops the blood from clotting. According to University of Florida Pathology Laboratories, proper specimen handling ensures accurate results. HNL Lab Medicine notes that clotted or hemolyzed samples are a common reason for unreliable results, and labs reject compromised specimens and ask for a redraw rather than report questionable data.
How Much Does a CBC with Differential Cost?
Through JustLabs, the CBC with differential is $6 plus one $18 order fee per order, so $24 all-in. The $18 order fee covers the Quest blood draw and the independent physician order, and it is charged once per order however many tests you add, so pairing the CBC with other tests does not add a second fee.
- No doctor visit or insurance needed. You order labs without a doctor visit, and a physician order is included.
- Drawn at Quest Diagnostics (Sonora Quest in Arizona). Book online through JustLabs or walk in.
- Results usually in 1-2 business days.
- HSA/FSA eligible, so you can use pre-tax dollars.
- Not available in NY, NJ, RI or HI.
The Southern Nevada Public Health Laboratory documentation shows this test uses standardized, widely available technology. Paying directly gets you the same Quest analysis as an insurance-billed order; read more about lab tests without insurance, or see how it works for the full process.
Recommended Test
Complete Blood Count with Differential
The CBC with Differential is one of the most commonly ordered blood tests, providing a comprehensive snapshot of your overall health through detailed blood cell analysis.
Includes 14 biomarkers
$6
Common Follow-Up Tests After an Abnormal CBC
A CBC result often leads to one or two targeted follow-up tests:
- Low MCV or suspected iron deficiency: an iron panel and ferritin
- High MCV: vitamin B12 and folate
- Signs of inflammation: high-sensitivity CRP or an ESR (sed rate)
- Anemia without an obvious cause: a reticulocyte count to see whether the bone marrow is keeping up
- Flagged or abnormal white cells: a peripheral blood smear with manual review, and sometimes flow cytometry ordered by a clinician
If you want a broader checkup alongside the CBC, the Basic Wellness Panel pairs it with a comprehensive metabolic panel, lipid panel and TSH. Because it includes lipids, it requires fasting.
Recommended Panel
Basic Wellness Panel
Save $2.50Our most affordable comprehensive screening includes the 4 tests doctors order most: CBC, Comprehensive Metabolic Panel, Lipid Panel, and TSH. Covers 30+ biomarkers in one blood draw.
Includes 37 biomarkers
$30
Fasting required
FAQ
What is the difference between a CBC and a CBC with differential?
A CBC counts your red cells, white cells and platelets and reports red cell indices such as MCV. A CBC with differential adds the breakdown of white cells into neutrophils, lymphocytes, monocytes, eosinophils and basophils, which helps point toward the cause of a high or low white count, for example bacterial versus viral infection or an allergic process.
What does "automated diff" mean on my lab order?
It means a hematology analyzer classified your white cells automatically rather than a technologist counting them on a microscope slide. Automated differentials are fast and precise for most samples. If the analyzer flags anything unusual, such as possible immature cells, the lab performs a manual smear review.
Do I need to fast for a CBC with differential?
No. The CBC is not a fasting test. A meal can shift a few values slightly, so if you are tracking your counts over time, test under similar conditions each time. Follow fasting instructions only if your order also includes a fasting test such as a lipid panel or fasting glucose.
How long do CBC with differential results take?
Through JustLabs, results are usually ready in 1-2 business days after your Quest blood draw. The analysis itself takes minutes; most of the time is transport and reporting.
What is a normal white blood cell count?
On Quest reports, the adult WBC reference range is 3.8-10.8 Thousand/uL. Ranges differ between labs and are different for children and during pregnancy, so read your result against the range printed on your report.
Can a CBC with differential detect leukemia?
It can raise the suspicion. Leukemia can cause very high or very low white counts or immature cells, which the analyzer flags for review. A CBC cannot confirm a diagnosis, and most abnormal results have common, non-cancer causes. Persistent or marked abnormalities need a clinician's evaluation.
How much does a CBC with differential cost without insurance?
Through JustLabs, it is $6 plus one $18 order fee, or $24 all-in, with no doctor visit or insurance needed. The fee is charged once per order, so adding other tests does not add another fee. It is HSA/FSA eligible.
What does it mean if my CBC is normal but I still feel unwell?
A normal CBC with differential rules out many blood and immune problems, but it does not evaluate your thyroid, metabolism, hormones or most nutrient levels. Other tests matched to your symptoms may be needed, and persistent symptoms are worth discussing with a clinician.
This article is for education only and is not medical advice. Talk with a healthcare professional about your results, especially values that are far outside the range, keep changing, or come with symptoms.
Related Reading
References
Kratz A, Lee SH, Zini G, Riedl JA, Hur M, Machin S, International Council for Standardization in Haematology. Digital morphology analyzers in hematology: ICSH review and recommendations. Int J Lab Hematol. 2019 Aug;41(4):437-447. doi: 10.1111/ijlh.13042. PMID: 31046197. https://pubmed.ncbi.nlm.nih.gov/31046197/
Cascio MJ, DeLoughery TG. Anemia: Evaluation and Diagnostic Tests. Med Clin North Am. 2017 Mar;101(2):263-284. doi: 10.1016/j.mcna.2016.09.003. PMID: 28189170. https://pubmed.ncbi.nlm.nih.gov/28189170/
Barnes PW, McFadden SL, Machin SJ, Simson E, international consensus group for hematology. The international consensus group for hematology review: suggested criteria for action following automated CBC and WBC differential analysis. Lab Hematol. 2005;11(2):83-90. PMID: 16024331. https://pubmed.ncbi.nlm.nih.gov/16024331/
Westengard J, Bull BS. Avoiding regression analysis pitfalls when calibrating white blood cell differential counters. Lab Hematol. 2004;10(3):137-43. PMID: 15479648. https://pubmed.ncbi.nlm.nih.gov/15479648/
Riley LK, Rupert J. Evaluation of Patients with Leukocytosis. Am Fam Physician. 2015 Dec 1;92(11):1004-11. PMID: 26760415. https://pubmed.ncbi.nlm.nih.gov/26760415/
Gauer RL, Braun MM. Thrombocytopenia. Am Fam Physician. 2012 Mar 15;85(6):612-22. PMID: 22534274. https://pubmed.ncbi.nlm.nih.gov/22534274/
Lippi G, Lima-Oliveira G, Salvagno GL, Montagnana M, Gelati M, Picheth G, Duarte AJ, Franchini M, Guidi GC. Influence of a light meal on routine haematological tests. Blood Transfus. 2010 Apr;8(2):94-9. doi: 10.2450/2009.0142-09. PMID: 20383302. https://pubmed.ncbi.nlm.nih.gov/20383302/
