20 May 2019 Plasma is the liquid part of blood. It represents on average 55% of the blood . It is yellowish in colour and is made up of: Water (around 92%); Plasma proteins (around 8%); Small amounts of other substances (carbon dioxide, urea, lactic acid, coagulation factors, antibodies, sodium, chlorine, among others). It is also the medium for transporting blood cells . Serum is obtained from plasma by separating the plasma proteins from other proteins involved in coagulation. This article was written with the support of physicians and other clinical professionals from the Hospital da Luz network. The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.