LAb eval part 3

Erythocyte Sedimentation Rate (ESR)

A laboratory test that measures the rate at which red blood cells settle in a tube over a specified period, indicating inflammation or disease in the body.

Rheumatoid arthritis, Infections, Certain malignancies, temporal arteritis, and Polymyalgia

ESR is used to detect these disease

C-Reactive Protein

A more reliable inflammatory marker. Used to detect or monitor diseases

Cardiovascular diseases and Metabolic Syndrome

Diseases that C-reactive protein detects or monitor

Westergren and Wintrobe Method

the two major methods of ESR determinantion

Westergren method

Widely used ESR method. The reference method when undiluted blood is used.

decreased

What is the interpretation when measuring ESR of healthy or normal individuals.

Normal RBCs have smaller mass and are negatively charged

This explains why the ESR of a healthy individual is measured to be decreased

Rouleaux formation

often described as “stack of coin appearance” of RBCs

Fibrinogen, b-globulins, pathologic immunoglobulins

Macromolecules that can alter the repulsive force of RBCs

Initial 10 mins

Rouleaux formation. RBCs stick together in stacks and only a small amount of sedimentation occurs.

40 mins

Rapid, constant settling. Rouleaux become heavier and settle downward a a fairly constant and fastest rate.

Final 10 mins

RBCs accumulate at the bottom of the tube and become tightly packed, causing sedimentation to slow down.

Freshly collected anticoagulated whole blood (Sodium citrate or EDTA)

Specimen of choice for ESR

0.105 M Sodium citrate

It is used as the anticoagulant-diluent solution; it is filtered and kept refrigerated without preservatives

300mm +- 0.5mm

Overall length

200mm

Length of the blood column

5.5mm +- 0.5mm

External diameter

2.65mm +- 0.15mm

Tube bore

Original Westergren method

It uses 3.8% sodium citrate as anticoagulant for whole blood. A black top tube is used. This method does not required dilution of blood

Modified Westergren method

It uses EDTA as an anticoagulant for whole blood. It is the most commonly used method and is recommended by the ICSH and CLSI. This is way cheaper and more convenient since other tests can be done along with ESR test.

2mL EDTA-anticoagulated WB + 0.5mL diluent solution (3.8% sodium citrate or 0.85% sodium chloride)

Dilution when using Modified Westergren method

4 hrs, 18*C - 25*C

Specimen must be analyzed within what time, and at what temperature?

4*C, 24 hrs, RT for 15 mins, mixed

Specimen may be stored at what temperature and up to how many hours prior testing and should be rewarmed at what temperature and should be what prior testing

0-15 mm/hr

ESR reference interval for males <50 yrs old

0-20 mm/hr

ESR reference interval for males >50 yrs old and for females <50 yrs old

0-30 mm/hr

ESR reference interval for females >50 yrs old

0-10 mm/hr

ESR reference interval for children

Clotting

Binding of oxalate to calcium can cause

RBC shrinkage

Excessive or inappropriate concentration of oxalate can cause

Zeta potential of RBCs

What does heparin alter in RBCs. If this is altered, the repulsive force between RBCs is counteracted.

30%

How many percent will ESR increase when the tube is tilted 3*

Spherical

What shape will the RBC take when the specimen sits at room temperature for more than 4 hours? This inhibits the formation of rouleaux

Red cell, Plasma composition, Mechanical or technical factors

Three general factors that affects ESR result

Hypercholesterolemia

Increased plasma lipids, which promotes RBC aggregation and alter RBC/plasma interactions, allowing RBCs to settle faster

Hyperfibrinogenemia

Fibrinogen reduces the RBC negative charge (zeta potential), promoting rouleaux formation which leads to faster settling.

Hypergammaglobulinemia

Promotes RBC aggregation/rouleaux which leads to faster sedimentation

Hypoalbuminemia

Reduced albumin allows other aggregating proteins to have a greater relative effect that leads to increased rouleaux.

Hyperalbuminemia

Helps maintain RBC separation and counteracts aggregation, which slows down settling

Hyperglycemia

Increased glucose concentration can increase plasma viscosity and alter RBC behavior, tending to slow sedimentation

Hypofibrinogenemia

less reduction of RBC repulsion meaning less rouleaux leading to slow settling.

Hypogammaglobulinemia

Fewer globulins meaning less RBC aggregation, leading to slower sedimentation

Increased bile salt

Can alter RBC surface properties and reduce rouleaux formation, leading to a slower sedimentation

Increased phospholipids

Can alter the RBC membrane/surface properties and interfere with the normal RBC aggregation, which results in a slower settling.

Anemia

Fewer RBCs provide less resistance to settling; RBC can sediment mor readily

Macrocytosis

Larger RBCs have greater mass and tend to settle more readily

Acanthocytosis

Irregularly shaped RBCs do not stack into rouleaux efficiently

Marked anisocytosis

Wide variation in RBC size interferes with orderly rouleaux formation and settling

Hemoglobin C

Decreased amount of this protein-containing RBCs may have altered shape/aggregation, reducing rouleaux settling

Microcytosis

Smaller RBCs have less mass and settle more slowly

Polycythemia

Increased RBC concentration makes the blood more resistant to sedimentation

Sickle cells

Abnormal shape prevents effective rouleaux formation and interferes with settling

Spherocytosis

Spherical RBCs have abnormal shape and do not form rouleaux normally

Thalassemia

Microcytosis and abnormal RBC morphology interfere with normal sedimentation

Leukemia

Produces very high abnormal WBC counts and is often associated with other factors such as anemia, inflammation, and increased plasma proteins that can elevate ESR

Marked leukocytosis

Very high WBC counts can contribute to increased sedimentation and may interfere with the normal RBC settling process

Menstruation

Hormonal and physiological changes, including mild changes in plasma proteins, may cause slight increased ESR. Moreover, bleeding leads to decreased plasma viscosity, hence the increased ESR

Pregnancy

Increased fibrinogen and plasma proteins, together with changes in RBC characteristics, promote faster sedimentation, leading to increased ESR.

Cachexia

Severe wasting and reduced production of plasma proteins can decrease rouleaux formation, leading to decreased ESR

Congestive heart failure

Altered blood flow dynamics or changes in plasma composition (increased plasma viscosity), leading to decreased ESR

Newborn Status

They have characteristics that reduce their tendency to form rouleaux, and their plasma has low fibrinogen, which means low ESR.

Disposable Westergren ESR System (Dispette)

Automatically dilutes the EDTA blood specimen

Nonabsorbent Safety Plug

Provides automatic zeroing of the specimen

Collar

Creates pressure that allows the blood to move up in the pipette up to the 0-mm mark

Wintrobe method

Abandoned and Obsolete method. Has the same principle as Westergren Method

11.5 cm (115mm)

Wintrobe tube length

3.00mm

Wintrobe tube bore

0 (top) to 100 (red markings; left side)

Wintrobe tube for ESR

100 (top) to 0 (white markings; right side)

Wintrobe tube for Microhematocrit

Anticoagulated whole blood (EDTA or Ammonium-potasium oxalte)

Specimen requirement for Wintrobe

Zeta Sedimentation ratio

Performed using Zetafuge and special capillary tubes. requires calculation to compute for ESR value

EDTA-Anticoagulated blood sample (approx. 0.2 mL)

Specimen requirement for Zeta Sedimentation Ratio

75mm

Zetafuge capillary tube length

2.3 mm

Zetafuge capillary tube outer diameter

2.0mm

Zetafuge capillry tube inner diameter

HCT(%) / Zetacrit(%) x 100

formula for ZSR

40-51%

Normal ZSR

51-54%

Boderline ZSR

55-59%

Mildly elevated ESR

60-64%

Moderately elevated ESR

>65%

Markedly Elevated ESR

Osmotic Fragility Test

Measures the ability of the red cells to take up fluid without lysing

Shape of RBC

Most important factor of OFT

Hereditary Spherocytosis (HS)

OFT is the most useful diagnostic test for what disease