Lab Tools & Reference

🔄 Unit Converter — SI (mmol/L) ↔ Conventional (mg/dL)

Each analyte has its own factor (based on its molecular weight) — never use one number for all. Pick a test, type a value in either box.

Factors are standard reference values; always confirm against your method/insert.

🧮 Lab Calculators

LDL Cholesterol (Friedewald)

LDL = Total Cholesterol − HDL − (Triglycerides ÷ 5), in mg/dL.

Corrected Calcium (for albumin)

Corrected Ca = Measured Ca + 0.8 × (4.0 − Albumin), in mg/dL.

Anion Gap

Anion Gap = Na⁺ − (Cl⁻ + HCO₃⁻). Typical reference ≈ 8–12 mmol/L.

Creatinine Clearance (Cockcroft–Gault)

CrCl = ((140 − age) × weight × [0.85 if female]) ÷ (72 × Serum Creatinine mg/dL).

Calculators are for laboratory reference and education only — not a substitute for clinical judgment or your instrument's method.

💡 Beer–Lambert Law & Optical Density (O.D.) limits

The Beer–Lambert law is the principle behind every colorimeter and biochemistry analyser. It states that the light a solution absorbs is directly proportional to the amount of substance in it (at a fixed wavelength and path length):

• A = Absorbance, also called Optical Density (O.D.) — no units
• ε (epsilon) = molar absorptivity / extinction coefficient (constant for a substance at a given wavelength)
• c = concentration of the analyte
• l = light path length through the cuvette (usually 1 cm)

In simple words: more analyte → more colour → more light absorbed → higher O.D. That is how the analyser converts an O.D. reading into a concentration.

Absorbance and % Transmittance:

Maximum optical (O.D.) limit

The law stays linear only up to a point. Beyond that, absorbance no longer rises proportionally with concentration and results become unreliable:

• Reliable range: about 0 – 2.0 A for most photometers
• Best accuracy: roughly 0.1 – 1.0 A
• Above ~2.0 A: linearity and accuracy are usually lost (at 2.0 A only 1% of light is transmitted)

Common causes of over-range O.D.: very high analyte level, too much sample volume, wrong wavelength, dirty/scratched cuvette, or air bubbles.

Exact linear limits depend on each instrument and reagent — always follow the kit insert.

🩸 Blood Collection Tube Chart (which tube for which test)

🗑️ Biomedical Waste Colour Coding (India — BMW Rules, 2016)

Simplified summary of India's Bio-Medical Waste Management Rules, 2016 (as amended). Follow your facility's SOP and current regulations.

🌡️ Fever Panel & CBC Correlation — Dengue · Malaria · Chikungunya · Typhoid

A quick guide to how the CBC typically behaves in common acute febrile illnesses, and which confirmatory test to run. Patterns are typical — not absolute.

For laboratory education and reference only. Not for diagnosing patients — clinical diagnosis is made by the treating physician using history, examination and confirmatory tests.

📈 Levey-Jennings Chart & Westgard Rules (Internal Quality Control)

Internal QC checks that your analyser is giving reliable results before you release patient reports. You run a known control serum, plot it, and apply rules to decide: accept or reject the run.

The Levey-Jennings (L-J) chart

A graph that plots each day's control value against the mean, with lines drawn at ±1SD, ±2SD and ±3SD. To build one: run the control about 20 times, calculate the mean and standard deviation (SD), then draw the lines and plot each new result.

Reading it: points should scatter randomly around the mean, most within ±2SD. Watch for two warning patterns:

• Shift — 6+ points suddenly staying on one side of the mean → a systematic change (new reagent lot, recalibration, new control vial).
• Trend — 6+ points steadily drifting up or down → gradual deterioration (reagent aging, light source, electrode wear).

Westgard multirules

A set of rules to decide accept/reject. 1₂ₛ is only a warning that tells you to inspect the other rules — it is not a reject on its own.

Standard Westgard multirule reference for education. Follow your laboratory's QC policy and the analyser/QC manufacturer's guidance.

🧊 Controls & Reagents — practical stability & extending shelf-life

Getting the most from control serum

• Store at 2–8 °C (or as the insert states); never leave at room temperature longer than needed.
• Bring to room temperature and mix gently before use — do not shake (foaming affects results).
• Aliquot reconstituted/opened controls into small portions to avoid repeated warming of the whole vial.
• Avoid repeated freeze–thaw — it degrades many analytes.
• Record the date opened / reconstituted and discard after the stated open-vial stability.
• Use clean, dry pipette tips — contamination is the fastest way to ruin a control.

Extending working-reagent life

• Keep bottles tightly capped; return to the fridge promptly after use.
• Protect light-sensitive reagents from direct light.
• Never pour used reagent back into the stock bottle.
• Watch for signs of deterioration: turbidity, colour change, drifting blanks or QC — replace if seen.
• Follow the insert's on-board / working-reagent stability — don't assume it equals the unopened shelf life.

General good-practice guidance. Always follow the specific product insert for exact storage and stability.