Complete Blood Count (CBC) with Differential and Platelets Blood Test

Eosinophils are a type of white blood cell involved in allergic and parasitic responses. This test examines sputum (phlegm coughed up from lungs) under a microscope to detect eosinophils. Elevated sputum eosinophils suggest eosinophilic airway inflammation, which may indicate asthma, eosinophilic bronchitis, parasitic infections, or allergic conditions. This test helps diagnose conditions causing chronic cough and guides treatment selection.

Basophils are immune cells that release histamine and other chemicals during allergic reactions and inflammation. This test measures basophil counts in synovial fluid (joint fluid), which helps diagnose joint inflammatory conditions like rheumatoid arthritis, gout, or septic arthritis. Elevated basophils in joint fluid indicate inflammation or immune response in the joint. Results guide diagnosis and treatment of joint disease.

Neutrophils are infection-fighting white blood cells. This test counts neutrophils in pleural fluid (fluid surrounding the lungs) to evaluate lung and pleural conditions. Elevated neutrophils in pleural fluid suggest infection, inflammation, or malignancy affecting the lungs or pleural lining. The test also notes that elevated neutrophils in prostatic secretions may indicate prostate inflammation or prostatitis. Analysis of pleural fluid composition, including neutrophil count, helps diagnose pneumonia with effusion, empyema (infected fluid), or other serious lung conditions requiring urgent treatment.

White blood cells (WBCs or leukocytes) are immune cells that fight infections and protect your body. This test measures WBC count in synovial fluid (fluid surrounding joints). Elevated WBC in joint fluid suggests infection, inflammation, or autoimmune disease affecting that joint. Very high counts may indicate septic arthritis (bacterial infection), while moderate elevation could indicate rheumatoid arthritis or other inflammatory joint conditions. This specialized test helps diagnose the cause of joint pain or swelling.

Platelets are small blood cells essential for blood clotting and preventing excessive bleeding. This blood test counts the number of platelets circulating in your bloodstream. Low platelet counts (thrombocytopenia) increase bleeding risk, while high counts (thrombocytosis) may indicate clotting risks or underlying disease. Platelet counts are affected by bone marrow disorders, medications, infections, and autoimmune diseases. This is a routine test included in complete blood counts to assess clotting function and overall blood health.

Monocytes are large white blood cells that help fight infections and clear damaged tissue. This specialized test counts monocytes in pericardial fluid (fluid around the heart). Elevated monocyte counts in pericardial fluid may indicate pericarditis (inflammation of the heart lining), infection, or autoimmune disease affecting the heart. This test helps diagnose serious cardiac conditions and inflammatory states. Results are interpreted alongside other fluid analysis tests for comprehensive cardiac assessment.

Red blood cells (erythrocytes) are the oxygen-carrying cells in your blood. This automated test counts the number of red blood cells in synovial fluid (joint fluid), which is abnormal since red blood cells should not be present in joints. Elevated RBC counts in joint fluid may indicate joint injury, bleeding into the joint, or traumatic arthrocentesis (needle puncture during fluid collection). This result helps differentiate between inflammatory and non-inflammatory joint conditions.

Mean sphered cell volume measures the average size of red blood cells when treated under standardized laboratory conditions. This specialized test provides information about red blood cell shape and hydration status, helping diagnose hemolytic anemias and hereditary conditions affecting RBC structure like spherocytosis. Abnormal values suggest specific types of anemia or blood disorders requiring further investigation and targeted treatment.

Hemoglobin is the iron-containing protein in red blood cells that carries oxygen throughout your body. A hemoglobin test measures the total amount of hemoglobin in blood, revealing whether you have anemia (too little) or polycythemia (too much). Low hemoglobin causes fatigue, shortness of breath, and weakness, while high levels can increase clot risk. This is one of the most common tests in clinical medicine and a core part of the complete blood count.

The erythrocyte sedimentation rate (ESR) measures how quickly red blood cells settle in a test tube over one hour. This simple test reflects inflammation levels in your body. Elevated ESR can indicate infections, autoimmune diseases, inflammatory conditions, or certain cancers. Low ESR is less common but may occur with blood disorders. ESR is often used alongside other tests to diagnose or monitor chronic inflammatory conditions, though it's not specific to any single disease.

Nucleated red blood cells (nRBCs) are immature RBCs that normally exit the bone marrow and mature before circulating in your blood. The presence of nucleated RBCs in peripheral blood is abnormal and suggests bone marrow stress or disease. This can indicate severe anemia, leukemia, infection, hemolysis, or other serious conditions. Finding nucleated RBCs on a blood smear typically warrants further investigation to identify the underlying cause.

Band form neutrophils (bands) are immature white blood cells released from the bone marrow into the bloodstream in response to acute infection or inflammation. An elevated band count, known as a "left shift," is a hallmark of bacterial infection and sepsis. Bands are counted as part of the manual differential on a complete blood count (CBC). Their presence signals the body's urgent demand for neutrophils and is one of the SIRS criteria used in critical care. Monitoring band counts helps track infection severity and response to antibiotic therapy.

Lymphocytes are a type of white blood cell crucial for the adaptive immune response, including B cells (which produce antibodies), T cells (which coordinate and carry out cell-mediated immunity), and NK cells (natural killer cells). This blood test counts lymphocytes as part of the complete blood count with differential. Elevated lymphocyte counts (lymphocytosis) may suggest viral infections, certain leukemias, or autoimmune conditions. Low lymphocyte counts (lymphopenia) can indicate immunodeficiency, bone marrow disorders, or the effects of immunosuppressive therapies.

Myelocytes are immature white blood cells normally found in bone marrow. Their presence in body fluids such as blood, pleural fluid, or peritoneal fluid is abnormal and may indicate serious conditions. Myelocytes in body fluids can suggest leukemia, severe infection, or other hematologic disorders. The number and type of myelocytes detected helps establish a diagnosis. This test is typically ordered when other findings suggest a blood cell disorder and requires interpretation alongside other cell counts and clinical findings.

Blasts are immature blood or bone marrow cells. Finding them in body fluids (blood, joint fluid, pleural fluid, etc.) is abnormal and concerning. In healthy individuals, blasts should not appear in body fluids—they should remain in bone marrow and blood. Their presence may indicate leukemia, other blood cancers, or malignant invasion into body cavities. This is a quantitative test that counts the number of blasts, which helps assess disease severity. Further testing and specialist evaluation are essential if blasts are detected.

Promyelocytes are immature white blood cells normally found in bone marrow, not in body fluids like blood or joint fluid. Detecting promyelocytes in body fluids is abnormal and may indicate serious conditions such as leukemia, particularly acute promyelocytic leukemia (APL), or leukostasis. The presence and quantity of promyelocytes helps diagnose blood cancers and assess disease severity. This finding requires urgent further investigation and specialist consultation.

Metamyelocytes are immature white blood cells found in bone marrow that normally do not appear in significant numbers in body fluids. Their presence in blood, joint fluid, or other body compartments is abnormal and may indicate leukemia, severe infection, or a bone marrow disorder. This test counts metamyelocytes as part of a differential analysis in body fluid samples. Elevated levels suggest the bone marrow is releasing immature cells prematurely, which warrants further investigation.

CLSI (formerly NCCLS) document "Reference Leukocyte Differential Count (Proportional) and Evaluation of Instrumental Methods", 1992, recommend the use of variant lymphocytes rather than atypical or reactive lymphocytes.

CD19 is a marker found on B lymphocytes, white blood cells that produce antibodies and fight infections. A CD19 cell count measures the number of B cells in your blood or bone marrow. Abnormally low CD19 counts may indicate immunodeficiency, leukemia, or complications from certain medications or treatments. Elevated counts can suggest chronic lymphocytic leukemia or other lymphoproliferative disorders. This test is particularly useful in diagnosing blood cancers and immune disorders.

Band neutrophils are immature white blood cells released from bone marrow during stress or infection. This test measures the percentage of band neutrophils relative to total white blood cells. Elevated bands (a left shift) typically indicate acute infection, inflammation, or leukemia. Normal blood contains mostly mature segmented neutrophils; a high proportion of bands suggests the bone marrow is urgently releasing immature cells to fight infection.

Platelets are cell fragments essential for blood clotting and stopping bleeding. This test counts platelets in blood, with the Rees-Ecker method being a manual counting technique. Normal platelet counts range from 150,000 to 400,000 per microliter. Low platelet counts (thrombocytopenia) increase bleeding risk, while high counts (thrombocytosis) increase clot risk. Abnormal counts may indicate bone marrow disorders, autoimmune disease, infections, or medication effects.