DLCO Predicted Calculator

Calculator

Educational support only. Use official reference equations and your lab’s reporting rules for clinical decisions.

Example data table

Values are illustrative, not lab reference output.

Formula used

Reference option A: North Indian adult equations (2016)

• DLCO_pred (Male) = −7.813 + 0.318·Ht − 0.624·Age + 0.00552·Age²
• DLCO_pred (Female) = −44.15 + 0.449·Ht − 0.099·Age
• VA_pred (Male) = −8.152 + 0.087·Ht − 0.019·Wt
• VA_pred (Female) = −6.893 + 0.068·Ht
• KCO_pred = DLCO_pred ÷ VA_pred

Ht in cm, Wt in kg, Age in years.

Reference option B: Height-age-sex-Hb model (2023)

• DLCO_pred = 5.58 · H(m)^1.69 · SexFactor · AgeFactor · (1 + 0.06·Hb)
• SexFactor = 1.15 (Male), otherwise 1.00
• AgeFactor = (1 − 0.006·Age) if Age > 35; (1 + 0.01·Age) if Age < 20

Hemoglobin correction (Cotes method)

• DLCO_Hb‑adj = DLCO_obs · (10.22 + Hb) / (1.7·Hb) for adult males and adolescent boys.
• DLCO_Hb‑adj = DLCO_obs · (9.38 + Hb) / (1.7·Hb) for females and children.

Oxygen tension adjustment (optional)

• DLCO_adj = DLCO · (1 + 0.0035 · (O₂ − 100)), where O₂ is an oxygen tension estimate in mmHg.
• Altitude mode estimates oxygen tension via PAO2 ≈ FiO2·(Patm−47) − PaCO2/RQ.

These formulas are provided for educational implementation. Clinical labs may use different reference sets and statistical lower limits of normal.

How to use this calculator

1. Choose a reference equation set that fits your population.
2. Enter sex, age, height, and weight.
3. Optionally enter hemoglobin to adjust the measured value.
4. Optionally enter measured DLCO to compute % predicted.
5. If available, enter measured VA to compute observed KCO.
6. Use altitude mode only when oxygen tension differs meaningfully.
7. Click Calculate to view results above the form.
8. Use export buttons to download a CSV or PDF report.

FAQs

1) What does DLCO measure?

DLCO estimates how efficiently gas transfers from alveoli to blood. It reflects membrane properties, capillary blood volume, and hemoglobin availability during the test.

2) Why do predicted values differ by reference set?

Prediction equations depend on study population, equipment, methodology, and statistical modeling. Your laboratory usually selects one reference standard to keep reporting consistent over time.

3) Why correct DLCO for hemoglobin?

Hemoglobin binds carbon monoxide during the maneuver. Low hemoglobin can reduce observed DLCO, while higher hemoglobin can increase it. Adjusting helps compare results more fairly across patients.

4) Does smoking affect DLCO results?

Recent smoking can raise carboxyhemoglobin and alter the measurement. Many labs ask patients to avoid smoking before testing and interpret results within the full clinical context.

5) What is VA and KCO?

VA is the alveolar volume participating in gas exchange during the maneuver. KCO is DLCO divided by VA and is sometimes used to interpret diffusion relative to lung volume.

6) How is “percent predicted” interpreted here?

This tool uses common cutoffs: ≥80% normal, 60–79 mild reduction, 40–59 moderate reduction, and <40 severe reduction. Your lab may use LLN or z-scores instead.

7) When should oxygen tension adjustment be used?

Use it when testing occurs at unusual altitude or with supplemental oxygen settings. If oxygen tension is close to normal room-air conditions, the factor will be near one.

8) What are the limitations of this calculator?

It cannot replace lab software, local reference standards, or clinician judgment. Units, reference populations, and LLN definitions can differ. Always compare with the official report produced by your laboratory.