CBC with Differential

The differential breaks white blood cells into 5 subtypes (neutrophils, lymphocytes, monocytes, eosinophils, basophils). The pattern helps distinguish bacterial vs viral infection, allergic response, or hematologic disease — clinical info a CBC without differential can't provide.

Plain CBC gives total WBC count, hemoglobin, hematocrit, platelets, MCV, MCH. CBC with Differential adds the 5-part WBC breakdown. Most modern labs auto-run the differential, so it's the default test ordered.

No fasting required. CBC is one of the few labs you can draw at any time of day after eating. Most people fast anyway because they're bundling it with a CMP or lipid panel (which do require fasting).

On TestWell, CBC with Differential is $21.99 — no insurance needed. Quest Direct lists the same test at $25, and walk-in hospital labs typically bill $80-100 without insurance. Same CLIA-certified labs, same biomarkers — TestWell just removes the markup.

The CPT code for CBC with automated differential is 85025. CBC without differential is 85027. Cash-pay patients don't need a CPT code to order through TestWell.

It usually indicates anemia — most commonly from iron deficiency (especially in menstruating women), but can also stem from B12/folate deficiency, chronic inflammation, or blood loss. The MCV (mean corpuscular volume) helps narrow the cause: low MCV suggests iron deficiency, high MCV suggests B12/folate deficiency.

Most often a bacterial infection (especially if neutrophils are elevated). Viral infections typically raise lymphocytes. Allergies and parasites raise eosinophils. Chronically elevated WBC without obvious cause warrants further workup.

Annually as part of a routine checkup. Every 3-6 months if you're on TRT, chemotherapy, or medications known to suppress bone marrow. Anytime you're investigating unexplained fatigue, fever, or bruising.

A basic CBC counts red cells, white cells, hemoglobin, hematocrit, and platelets. The 'with differential' version also breaks white cells into their five types (neutrophils, lymphocytes, monocytes, eosinophils, basophils), which helps tell infection types apart and flags some blood conditions. The basic CBC is cheaper if you do not need the breakdown.

That pattern (a 'left shift' toward neutrophils) most often reflects a bacterial infection, acute inflammation, or physical stress — even a hard workout or steroid dose can produce it. The reverse pattern (low neutrophils, high lymphocytes) leans viral. Neither is a diagnosis by itself; it is a directional clue your provider reads alongside symptoms.

It is usually the first test that raises the question — very high or very low white counts, blasts noted on the report, or unexplained combinations of anemia and low platelets can prompt a hematology referral. But a CBC alone cannot confirm or rule out leukemia; that requires follow-up testing (peripheral smear, sometimes marrow biopsy). If your counts are normal, leukemia is very unlikely to be the explanation for your symptoms.

Both have a role. A CBC shows whether anemia is already present, but ferritin drops first and catches iron deficiency before the CBC changes. If fatigue and low iron are the concern, ferritin (often with iron and TIBC) is the more sensitive early test.

Ordered directly, a CBC with Differential test lists at $29.00 at Quest Health (Quest Diagnostics' own site) and $29.00 at Labcorp OnDemand (prices checked September 2026). TestWell orders the same test at the same Quest or Labcorp patient service centers for $21.99 — $27.99 all-in with the $6 per-order lab processing fee — paid out of pocket at checkout with no insurance, doctor's visit or draw fee; HSA and FSA cards are accepted.

CBC with Differential test results are typically ready in 1–3 business days after your draw at Quest or Labcorp. TestWell emails you the moment they post, and your results dashboard shows each marker against its reference range with a plain-English explanation.

Smoking and nicotine, recent blood donation, alcohol and exercise can change a CBC with Differential test result without anything being wrong. Smoking and nicotine can raise RBC and WBC — tell the clinician; a high hematocrit in a smoker is usually smoking, not polycythemia. Recent blood donation can lower RBC and can shift MCV — wait 6–8 weeks after a whole-blood donation for an anemia baseline. Alcohol can raise MCV — reflects long-term intake; not a one-night effect. Exercise can raise WBC — rest the morning of the draw. Each factor is covered on our physician-reviewed "Before your test" pages; when one applies, the fix is usually to remove it and retest.

Order the CBC with Differential test online from TestWell for $21.99 (plus a $6 per-order lab processing fee) — no doctor's visit, referral or insurance needed. A licensed physician authorizes the order, then you walk into any Quest or Labcorp patient service center near you for the draw (the lab locator on our site lists the closest ones by ZIP code), and results arrive in 1–3 business days.

The CBC with Differential test is Quest Diagnostics test code 6399 ("CBC (includes Differential and Platelets)"), Labcorp test number 005009 ("CBC With Differential/Platelet"), BioReference code 0053-9 ("CBC w/Diff, Platelet Ct.") (CPT 85025). TestWell orders it under those codes for $21.99 at Quest, Labcorp or BioReference — no doctor's visit or insurance required, results in 1–3 business days. Codes verified against the labs' catalogs in 2026.