(complete Blood Count (CBC

من طرف **المسلمانى** الثلاثاء مارس 16, 2010 7:18 pm

Complete Blood Count (CBC)

The CBC is a basic screening test and is one of the most frequently ordered laboratory procedures. The findings in the CBC give valuable diagnostic information about the hematologic and other body systems, prognosis, response to treatment, and recovery. The CBC consists of a series of tests that determine number, variety, percentage, concentrations, and quality of blood cells:

White blood cell count (WBC): leukocytes fight infection
Differential white blood cell count (Diff): specific patterns of WBC
Red blood cell count (RBC): red blood cells carry O₂ from lungs to blood tissues and CO₂ from tissue to lungs
Hematocrit (Hct): measures RBC mass
Hemoglobin (Hb): main component of RBCs and transports O₂ and CO₂
Red blood cell indices: calculated values of size and Hb content of RBCs; important in anemia evaluations
Mean corpuscular volume (MCV)
Mean corpuscular hemoglobin concentration (MCHC)
Mean corpuscular hemoglobin (MCH)
Stained red cell examination (film or peripheral blood smear)
Platelet count (often included in CBC): thrombocytes are necessary for clotting and control of bleeding
Red blood cell distribution width (RDW): indicates degree variability and abnormal cell size
Mean platelet volume (MPV): index of platelet production

RBCs

Many physiologic variants affect outcomes: posture, exercise, age, altitude, pregnancy, and many drugs.

Hematocrit

Physiologic variants affect Hct outcomes: age, sex, and physiologic hydremia of pregnancy.

Hemoglobin

Physiologic variations affect test outcomes: high altitude, excessive fluid intake, age, pregnancy, and many drugs.

MCHC

High values may occur in newborns and infants.
Presence of leukemia or cold agglutinins may increase levels. MCHC is falsely elevated with a high blood concentration of heparin.

MCH

Hyperlipidemia and high heparin concentrations falsely elevate MCH values.
WBC counts greater than 50,000/mm³ falsely elevate Hb values and falsely elevate the MCH.

WBC Count

Hourly variation, age, exercise, pain, temperature, and anesthesia affect test results.

Neutrophils and Eosinophils

Physiologic conditions such as stress, excitement, exercise, and obstetric labor increase neutrophil levels. Steroid administration affects levels for up to 24 hours.
The eosinophil count is lowest in the morning and then rises from noon until after midnight. Do repeat tests at the same time every day. Stressful states such as burns, postoperative states, and obstetric labor decrease the count. Drugs such as steroids, epinephrine, and thyroxine affect eosinophil levels.

Platelets

Physiologic factors include high altitudes, strenuous exercise, excitement, and premenstrual and postpartum effects.
A partially clotted blood specimen affects the test outcome.

Interventions

Pretest Patient Care for Hemogram, CBC, and Differential (Diff) Count (All Components)

Explain test procedure. Explain that slight discomfort may be felt when skin is punctured. Refer to venipuncture procedure for additional information.
Avoid stress if possible because altered physiologic status influences and changes normal hemogram values.
Select hemogram components ordered at regular intervals (eg, daily, every other day). These should be drawn consistently at the same time of day for reasons of accurate comparison; natural body rhythms cause fluctuations in laboratory values at certain times of the day.

Dehydration or overhydration can dramatically alter values; for example, large volumes of IV fluids can â€œdiluteâ€‌ the blood, and values will appear as lower counts. The presence of either of these states should be communicated to the laboratory.
Fasting is not necessary. However, fat-laden meals may alter some test results because of lipidemia.
Some medications and other substances can alter results. Obtain a current medication history from the patient.
A high WBC count or diseases that cause RBCs to agglutinate may alter test results.

من طرف **المسلمانى** الجمعة أبريل 02, 2010 7:26 pm

(complete Blood Count (CBC

(complete Blood Count (CBC

رد: (complete Blood Count (CBC