Spirometry is the measure of lung function. The total lung capacity (TLC), functional residual capacity (FRC), residual volume (RV), and vital capacity (VC) are all values that can be tested using this method. Spirometry is used to help detect, but not diagnose, respiratory issues like COPD, and asthma. It is a simple and cost effective screening method. Further evaluation of a person's respiratory function can be done by assessing the minute ventilation, forced vital capacity (FVC), and forced expiratory volume (FEV). These values differ in men and women because men tend to be larger than women.