Blood plasma is the liquid medium that carries various substances throughout the body. Comprising over half of the body’s total blood volume, it is a complex mixture of water, proteins, electrolytes, hormones, and nutrients. Plasma also transports waste products for removal and maintains the body’s fluid balance.
The Appearance of Healthy Plasma
When separated from other blood components, healthy plasma typically appears as a clear, pale yellow or straw-colored liquid. Its hue is primarily due to its composition, which is about 90-92% water. The remaining percentage consists of dissolved solids, including proteins (like albumin and globulins), electrolytes, hormones, vitamins, and glucose.
Bilirubin, a natural pigment formed when red blood cells break down, significantly contributes to plasma’s yellow color. Other minor contributors to the yellow tint include dietary carotenoids and trace amounts of hemoglobin.
Common Plasma Color Variations
While healthy plasma is consistently pale yellow, its color can change, signaling various internal conditions. These variations are often observed during laboratory analysis after plasma is separated from whole blood, with its appearance shifting from its normal clear, straw-like state to a range of other colors.
Plasma may become darker yellow or orange, milky or cloudy, or take on reddish, brownish, or greenish tints. These visual changes provide initial clues for further investigation into a person’s health.
What Different Colors Indicate
Dark yellow or orange plasma, often described as icteric, indicates significantly elevated bilirubin levels. This condition, known as jaundice, typically suggests liver dysfunction (e.g., hepatitis or cirrhosis) where the liver cannot process bilirubin effectively. It can also indicate excessive red blood cell breakdown (hemolysis) or inherited conditions like Gilbert’s Syndrome.
Cloudy or milky plasma, referred to as lipemia, is caused by high concentrations of lipids, including triglycerides and cholesterol. This can occur temporarily after a fatty meal. However, persistent lipemia often points to metabolic disorders like hyperlipidemia, where the body struggles to metabolize fats.
Reddish plasma, or hemolysis, results from ruptured red blood cells releasing hemoglobin. This can be an artifact of improper blood collection or handling, or indicate medical conditions causing premature red blood cell destruction, such as hemolytic anemia.
Brownish or blackish plasma is less common but concerning. It may suggest methemoglobin, an altered hemoglobin form from drug toxicities or severe hemolysis. Myoglobin release from muscle damage (e.g., rhabdomyolysis) can also contribute to a dark brown appearance.
Greenish plasma is rare but has various causes. High levels of biliverdin, a green pigment from heme breakdown, or elevated ceruloplasmin, a copper-containing protein, may cause this discoloration. Ceruloplasmin levels can be influenced by hormonal medications, pregnancy, or conditions like rheumatoid arthritis. In rare instances, pigments from bacterial infections, particularly Pseudomonas aeruginosa, might lead to a greenish tint. These color variations are general indicators; only medical professionals can provide an accurate diagnosis based on comprehensive testing and clinical evaluation.