Respiratory

FEV1/FVC Ratio

Normal Range
Typically > 70-80% (Age dependent)
Sample Type
Standard
Fasting
No
Unit
%

The FEV1/FVC ratio (Tiffeneau-Pinelli index) is a fundamental parameter in spirometry used to differentiate between obstructive and restrictive lung diseases. It represents the proportion of the person's vital capacity they can expire in the first second of a forced exhalation. In obstructive diseases (like asthma or COPD), air flows out of the lungs slowly, reducing the FEV1 more than the FVC, thus lowering the ratio.

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Interactive
%

Enter your lab result to see where you stand compared to the standard reference range.

Why Context Matters

Poor patient effort or technique during the spirometry test is the most common cause of inaccurate ratios. Additionally, in the elderly, the ratio naturally declines, potentially leading to 'over-diagnosis' of COPD if age-adjusted norms (Lower Limit of Normal - LLN) are not utilized.

Lab ranges are statistical averages, not biological laws. "Normal" for a 20-year-old male isn't normal for a 60-year-old female.

Clinical References

Source-of-truth databases and clinical guidelines for FEV1/FVC Ratio:

Research & Guidelines

Related Indicators

Pulmonary Function Test

View Range

Forced Vital Capacity (FVC)

View Range

Forced Expiratory Volume (1s) (FEV1)

View Range
DR

Medically Reviewed by Dr. Binoy Babu, MBBS

Board Certified Doctor • 10+ Years Clinical Experience

Dr. Babu is a practicing physician dedicated to empowering patients with clear, actionable medical information. He founded 2opi to bridge the gap between complex lab reports and patient understanding, ensuring everyone has access to a reliable second opinion.

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