Calculations

Work the bench math: dilution factors and volumes, serial dilutions, aliquots, and the chemistry calculations behind a reported result.

Steps

1
Dilution factors and patient results12 min
- Calculate a dilution factor and specimen fraction from prepared volumes
- Calculate the original concentration from a diluted measurement
At the bench Prepare a dilution using the required sample and diluent volumes
2
Making a dilution and checking the reading13 min
- Calculate the specimen and diluent volumes for a chosen dilution
- Decide whether a diluted reading falls inside the measuring interval before reporting
At the bench Prepare a dilution using the required sample and diluent volumes · Check the dilution factor and reportable range of a diluted chemistry result
3
Serial dilutions14 min
- Calculate a cumulative dilution factor
- Calculate the destination concentration in a serial dilution step
- Predict how a transfer or diluent volume error changes a serial dilution
At the bench Prepare a dilution using the required sample and diluent volumes
4
Aliquots, withdrawal and mixing12 min
- Calculate the amount of solute in an aliquot
- Predict the concentration after withdrawing a well-mixed aliquot
- Mix a dilution before transferring the next aliquot
At the bench Prepare a dilution using the required sample and diluent volumes
5
Iron-binding capacity and transferrin saturation13 min
- Calculate TIBC from transferrin using the procedure's factor and units
- Calculate TIBC or UIBC from the other iron-capacity measurements
- Calculate transferrin saturation from serum iron and TIBC
6
Globulin, indirect bilirubin and LDL cholesterol14 min
- Calculate globulin and the albumin/globulin ratio
- Calculate the indirect bilirubin fraction from total and direct results
- Calculate non-HDL cholesterol from total and HDL cholesterol
- Calculate Friedewald LDL cholesterol in mg/dL or mmol/L

More skills in this part

Partitioned-interval example

Report a result against the interval for the patient's registered age and sex

In the lab

Apply the skills from these steps to a case.

Try this at the Dilution stationCK · U/L>1000UNDILUTED · ABOVE AMR1:5 to 500 µLDilute specimen Try this at the Dilution stationCK · U/L>1000UNDILUTED · ABOVE AMR1:8 to 800 µLDilute specimen Try this at the Dilution stationOriginal · mg/L100Source concentrationUnequal steps: 2, 5, 10Dilute specimen Try this at the Dilution stationOriginal · mg/L100Source concentrationThree twofold stepsDilute specimen

1 more at the stations

Try this at the Dilution stationOriginal · mg/L100Source concentrationThree tenfold stepsDilute specimen

Bench references

Keep these guides beside the related calculation or decision.

Calculations, quick reference 1 of 10
01 / 10 · Calculations
Dilutions and dilution factors
Parts, volumes, serial steps, and the reported result
Adding diluent lowers concentration. The dilution factor (DF) is the final volume divided by the specimen volume. A DF of 5 gives one fifth of the original concentration.
Example: 1:5 dilution
Here, 1:5 means specimen:final volume: one specimen part plus four diluent parts. A written 1 + 5 makes six parts, DF = 6.
Specimen
100 µL
Diluent
100 µL
Diluent
100 µL
Diluent
100 µL
Diluent
100 µL
500 µL final volume = 100 µL specimen + 400 µL diluent.
Equal-volume schematic. µL = microliter.
Calculating the dilution factor
Formula
DF = final volume ÷ specimen volume
In the 1:5 example
Final volume = 500 µL
Specimen volume = 100 µL
DF = 500 ÷ 100 = 5
Volumes and factor
Specimen volume
Final volume ÷ DF
Diluent volume
Final − specimen volume
Prepare 1:10, final 1.0 mL.
Specimen = 1.0 ÷ 10 = 0.10 mL.
Diluent = 1.0 − 0.10 = 0.90 mL.
mL = milliliter. 1 mL = 1,000 µL.
Concentration and result
Diluted concentration
Original concentration ÷ DF
Original concentration
Diluted concentration × DF
A 1:5 aliquot measures 84 U/L.
84 × 5 = 420 U/L in the original specimen. U/L = units per liter.
Apply the factor once: an analyzer-corrected 420 U/L stays 420 U/L. Use the method's diluent and validated measuring range.
Cumulative dilution factor
Original specimen
1:5 step
Total DF = 5
1:4 step from that mixture
Total DF = 5 × 4 = 20
Each step dilutes the well-mixed solution from the preceding tube, so the cumulative dilution factor is the product of the step factors. A result of 12 mg/dL in the second tube gives 12 × 20 = 240 mg/dL in the original specimen. mg/dL = milligrams per deciliter.
https://latticemls.org/guides/dilutions/ · Sources checked September 5, 2026 · vc32c65d9
© LatticeMLS · CC BY-NC-SA 4.0
Calculations01 / 10Dilutions and dilution factorsParts, volumes, serial steps, and the reported result

Add your earlier progress to your account?

Remove this progress from this device?

Which plan do you want to keep?

Study progress is waiting to be saved

Calculations

Steps

More skills in this part

Partitioned-interval example

Dilutions and dilution factors

Example: 1:5 dilution

Calculating the dilution factor

Volumes and factor

Concentration and result

Cumulative dilution factor