Module 1b Flashcards
(31 cards)
What is a CBC? The components? And why would you order it?
Complete blood count
- tests that determine the number, variety, percentage, concentrations, & quality of blood cells
- WBC count, RBC count, Hb (Hgb), Hct, RBC indices, platelets
- NOT screening unless select pre-op visits or pregnancy b/c too vague of a test to establish a diagnosis (exceptions are in narrow categories)
- Frequently ordered, gives wealth of information
What are the advantages, disadvantages, and costs of a CBC?
- Advantages:
– many, similar test results in one panel
– Info to evaluate common blood disorders
– One venipuncture - Disadvantages: might be too much information (really need platelet/WBC for anemia)
- Cost: $10-150, (Hb/Hct - $25)
What are interfering factors for a CBC?
- ALL: exercise (inc. O2 skew toward RBC), altitude (initially lower values, accumulate higher values)
- Heparin: falsely elevate RBC indices
- Pain inc WBC
- OB labor inc WBC
- Eosinophils time of day (measure at same time consistently to compare)
What is the WBC count portion of a CBC?
- Fight infection: phagocytosis, Ab
- Level correlated to severity of disease
What is the RBC count portion of a CBC?
- Carries O2 lungs –> tissue & CO2 reverse
- Contains Hb to combine with gases (gives color)
- Perfectly designed shape to give Hb max surface to react
- Examines adequacy of RBC production in bone marrow
What is the Hemoglobin (Hb/Hgb) portion of a CBC?
- Heme (red porphyrin) + globin (protein)
- 1g Hb can carry 1.34 mL O2/100mL blood
- Indicates O2 carrying capacity (not all RBC have same amount Hb)
- Screen/assess severity of/monitor treatment of anemia (1st indicator to check)
What is the Hematocrit (Hct) WBC count portion of a CBC?
- “to separate blood”: centrifuge separates plasma & blood cells
- measures RBC mass
- Screen/assess severity/monitor treatment anemia (1st indicator to check)
*Transfusions are ordered by units of PRBCs (Packed red blood cells)
What is the RBC indices portion of a CBC?
- Define size & Hb content of RBC count
– MCV
– MCH
– MCHC
– RDW - Calculations based on other measurements
What is the difference between MCV, MCHC, and MCH?
- MCV: mean corpuscular (RBC) volume
– ave vol of 1 RBC
– Anemia descriptors: microcytic, normocytic, macrocytic - MCHC: mean corpuscular Hb concentration
– ave concentration Hb per RBC
– most value: monitoring anemia therapy
– low: hypochromic - MCH: mean corpuscular Hb
– ave weight of Hb per RBC
– valuable for Dx severe anemia
What is RDW?
- Automated measurement of variation in RBC size
- Elevated: wide size variation
– iron deficiency, sickle cell anemia, more than one type of anemia - Normal: acute blood loss, anemia of chronic disease
- Help fine-tune diagnosis anemia
High RDW may mask anemia making Hb appear normal
What is the platelet portion of a CBC?
- aka thrombocytes, smallest formed element of blood
- blood clotting, vascular integrity
- assess bleeding disorders: thrombocytopenia, liver disease, malignancies
– 50% pt w/ unexpected platelet inc have malignancy - Increased: “thrombocythemia/thrombocytosis”
– Myeloproliferative diseases (polycythemia vera)
– Splenectomy
– Asphyxiation
– Iron deficiency anemia - Decreased
– idiopathic thrombocytopenic purpura/neonatal purpura
– pernicious, aplastic anemias
– heart failure
What is haematopoiesis?
Hematopoetic stem cells in the bone marrow differentiate into WBC, RBC, and platelets
What is a WBC differential?
- An addition to the CBC that differentiates WBCs into their categories.
Elevation indicates… - Neutrophil: bacterial infection
- Eosinophils: allergies & parasites
- Basophils: parasites, some allergies
- Lymphocytes; viral infections
- Monocytes: severe infections
What are reticulocytes?
- young, immature, non-nucleate (genetic material present but not condensed into nucleus) RBC
- Measured by “retic count”
– Help differentiate cause of anemia
– Dec: lack of production: anemia of chronic disease
– Inc: excessive destruction: hemolytic anemias Sickle Cell anemia
Why order a blood culture & sensitivity?
- Dx bacteremia (bacteria in blood)
- Dx other pathogens in blood (fungus, parasites)
- Determine pathogen susceptibilities to antimicrobial therapies for Tx
What would clinical signs and symptoms of bacteremia be?
Chills and fever in pt with
- UTI
- Infected burns
- Rapidly progressing skin infection
- Postoperative fever or would infection
- Indwelling venous or arterial catheter
- Fever of unexplained origin (FUO)
What is the significance of bacteremia?
- Presence of bacteria in blood x=
- Sepsis: life-threatening organ dysfunction caused by dysregulated response to infection (starts with bacteremia)
- Clinical syndromes associated with bacteremia:
– Infective endocarditis
– Vertebral osteomyelitis
– Meningitis
What is the procedure of a blood culture & sensitivity?
- Acute febrile illness:
– 2 separate sets from 2 separate sites
– set = aerobic + anaerobic
– 2 sites to demonstrate systemic
– prior to starting antibiotic therapy when possible (Tx skew results) - FUO
– 2 sets 5-10 min apart, possibly 2 more 25-48 hrs later (base line and see if increase)
What is the difference between minimum inhibitory concentration and minimum bactericidal concentration?
- MIC: lowest concentration of antimicrobial agent preventing all visible growth of microorganism after overnight incubation
- MBC: lowest concentration of antimicrobial agent required to achieve bactericidal killing reduction 99.9% after plating on antibiotic free media
What does resistant/sensitive/and intermediate mean?
- Resistant: organisms are not susceptible to antibiotic at any dose
- Sensitive: organisms are inhibited by usual dose
- Intermediate: organisms are only inhibited by maximal dose
Define hematuria, pyuria, proteinuria, glucosuria, ketonuria, hemoglobinuria, myoglobinuria:
____uria = presence of _____ in the urine
- Hematuria: blood
- Pyuria: white blood cells
- Proteinuria: abnormal quantities of protein
- Glucosuria: abnormal quantities of glucose
- Ketonuria: ketones
- Hemoglobinuria: free hemoglobin
- Myoglobinuria: myoglobin
- Hematuria, hemoglobinuria, myoglobinuria: all may show up as positive urine dipstick for blood
What are “in the urine” tests?
- Chemical tests: lab & office (strip & chromatographically)
- Urine microscopy:
- Urine culture
What are the UA specimen collection procedures?
- Random specimen “dirty catch” (not sterile)
– clean, dry container –> disposable urine cup –> biohazard bag
– timing & preparation X emphasized (drug screen, Gonorrhea, Chlamydia) - Clean-catch (not sterile but dec risk contamination)
– May wipe urethral area (not alcohol wipe)
– Collect mid-stream in urine cup –> biohazard bag (culture, UTI concern)
What are the special specimen collection cases?
- Babies: use sticky bag
- Children: bribery or tell alternative
- Indwelling catheter: check time & cleanliness
- Suprapubic aspiration: US –> needle into bladder through abdomen
