Surfactant–albumin ratio

The surfactant-albumin ratio (SAR) is a ratio of two protein components in the lung surfactant, a substance that helps to reduce the surface tension in the lungs and keep them open. The SAR is calculated by dividing the amount of surfactant protein B (SP-B) by the amount of surfactant protein A (SP-A). The SAR is thought to be an indicator of the functional state of the lung surfactant, and a low SAR is associated with lung diseases such as acute respiratory distress syndrome (ARDS) and chronic obstructive pulmonary disease (COPD).

‎