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Section 2 of 6 · Open sections

Required section · Section 2 of 6

Measurements feed a pattern

Classify a result by what the analyzer method card says it measures or calculates, not by its clinical importance. In this impedance example, RBC and platelet count are measured pulse counts; hemoglobin is measured by SLS photometry after lysis; hematocrit may be measured or derived depending on the configured method; MCV, MCH, and MCHC are calculated from stated inputs. A method card is a teaching aid that summarizes an analyzer family; it is not the instrument instructions for use (IFU), a local validation record, or a release rule.

Keep four concepts separate: a method definition explains the signal; a reported-result definition specifies calculation and units; review status means flags, limits, or criteria that trigger local review; calibration and quality status document whether the instrument system is acceptable for use. A result can be measured and still need review, and a correctly calculated index is not proof of calibration or patient-result validity.

Use declared inputs and units before calculating. MCV (fL) = hematocrit (%) ÷ RBC (× 10^12/L) × 10; MCH (pg) = hemoglobin (g/dL) ÷ RBC × 10; MCHC (g/dL) = hemoglobin ÷ hematocrit × 100. Plateletcrit (%) = platelet count (× 10^9/L) × MPV (fL) ÷ 10,000 when that is the local analyzer definition.

Illustrative drawing — this picture was drawn rather than captured.

Diagram labels required inputs and units for MCV, MCH, MCHC, absolute neutrophils, and plateletcrit; it distinguishes measured inputs from calculated outputs.
Figure 1Input-and-unit dependency aid for RBC indices, absolute differential, and plateletcrit.

Identify the result definition and required inputs before comparing a relationship; then use local review criteria.

  1. Declare the method and status

    Read the analyzer family/IFU and distinguish measured, calculated, review, and calibration/QC status.

  2. Check inputs and units

    Confirm RBC, hemoglobin, hematocrit, WBC, differential percentage, platelet count, and MPV units before calculation.

  3. Calculate or compare

    Use the stated formula and local rounding only as a consistency screen.

  4. Choose bounded review

    Investigate specimen, analytic, or clinical-change evidence under local policy before release.

Knowledge checks

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Knowledge check 1

Which labels must be kept separate on an analyzer teaching card?

Choose at least 3 options.

Section status

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The module finishes after every required section is marked done and every check in those sections is correct.