(+92) 320 0038000
ESR Solution (3.8% Sodium Citrate) supplied by laboratory distributors like IBEX SCIENCES is a specialized, ready-to-use anticoagulant solution. It is specifically formulated for performing the Erythrocyte Sedimentation Rate (ESR) test in clinical hematology laboratories, most commonly via the traditional Westergren method.
The ESR is a non-specific marker used to detect and monitor systemic inflammation, infection, tissue injury, or autoimmune malignancies (such as rheumatoid arthritis or polymyalgia rheumatica). [1]
Core Chemical Principle & Composition
The solution acts as a reversible anticoagulant that preserves cell morphology while facilitating proper sedimentation: [1]
- 3.8% Sodium Citrate (C₆H₅Na₃O₇ ⋅ 2H₂O): This concentration corresponds to a 0.129 mol/L solution. [1]
- Anticoagulation Mechanism: It prevents blood clotting by chelating (binding) the ionized calcium (Ca²⁺) present in the blood plasma. Calcium is an essential cofactor (Factor IV) in the coagulation cascade; without free calcium ions, thrombin cannot form, and the clotting process is halted. [1, 2]
- Isotonicity: At 3.8%, the solution is perfectly isotonic with human blood. This prevents the red blood cells from swelling or shrinking (crenating), preserving their natural biconcave shape and true surface area—both of which are critical for an accurate settling rate.
Standard Manual Laboratory Procedure (Westergren Method)
To achieve precise, standard-compliant results, clinical technicians follow a strict dilution and setup protocol:
- Mixing Ratio (1:4 Proportion): The Westergren method requires a precise ratio of 1 part sodium citrate solution to 4 parts whole blood.
- Example formulation: Combine exactly 0.5 mL of ESR Solution with 2.0 mL of fresh whole blood (or blood previously collected in an EDTA tube) in a clean tube.
- Mixing: Invert the tube gently at least 8 to 10 times to ensure the anticoagulant is homogeneously distributed throughout the specimen. Do not shake aggressively, as this can cause hemolysis or introduce micro-bubbles.
- Tube Setup: Draw the citrated blood mixture into a clean, dry Westergren pipette up to the exact 0 mm mark. Ensure there are no air bubbles trapped in the column.
- Placement: Insert the filled pipette vertically into a designated Westergren stand. The stand must be perfectly level and kept completely free from vibrations, direct drafts, or sunlight.
- Timing & Reading: Leave the tube undisturbed for exactly 60 minutes (1 hour). At the 1-hour mark, read the distance from the bottom of the plasma meniscus to the top of the column of packed red blood cells. Record the result in mm/hour.
Clinical Interpretations & Visual Interference
During the 1-hour period, inflammatory proteins in the plasma (like fibrinogen and globulins) neutralize the negative surface charges on the red blood cells, causing them to aggregate into coin-like stacks called rouleaux. Heavier rouleaux settle through the plasma significantly faster, yielding an elevated ESR value.
- Normal Reference Ranges: Generally under 15 mm/hr for young men and under 20 mm/hr for young women (values naturally increase with age).
- Visual Check: While reading, technicians must also check for plasma abnormalities, such as lipemia (milky plasma indicating high lipids) or icterus (deep yellow plasma indicating high bilirubin), which can alert the laboratory to secondary metabolic shifts.
Crucial Bench Management & Storage
- Precise Dilution Dependency: Deviating from the 1:4 ratio will invalidate the test. Too much sodium citrate dilutes the blood excessively, artificially slowing the sedimentation rate and giving a false-low result. Too little citrate can lead to micro-clots, which halt sedimentation completely. [1]
- Microbial Prevention: Sodium citrate solutions can easily grow molds or bacteria if contaminated. Never return unused solution back into the stock bottle. Store the bottle tightly capped at room temperature (15–30°C). If cloudiness or floating filaments appear in the fluid, discard it immediately.
- Temperature Stability: Perform the test at room temperature (20–25°C). Cold room temperatures increase plasma viscosity, slowing the settling rate, while excessively hot laboratory benches can falsely accelerate sedimentation. [1]
Reviews
There are no reviews yet.