Bruises change color as the days pass from their initial formation. This change is normal and the phases it goes through respond to changes in the hemoglobin of the blood.
When bruises change color, many people are alarmed. They think that this modification is something abnormal and that a complication is happening within the injury.
The truth is that the change in color of bruises is something logical and natural. The hemoglobin they contain, as we will see later, undergoes chemical changes that alter its composition, and we see this through the skin as a change in colors.
And it is that bruises or hematomas are collections of blood that is trapped under the skin. Another technical name is ecchymosis, although it is preferred to distinguish the characterization, speaking of ecchymosis when the lesion is flat, and bruising when the skin is raised.
In a bruise there is no communication with the outside. That is, the skin where the lesion sits do not usually have wounds, so the blood under it is under pressure, looking for a way to escape. Failing to do so, hemoglobin degenerates due to stagnation and the passing of days.
What is hemoglobin and why do bruises change color from it?
We have been talking about hemoglobin as the main cause for bruising to change color. This is so because the substance in question, contained in red blood cells, is a protein with a certain cycle of existence within the body.
The primary function of hemoglobin is to transport oxygen to the tissues. The oxygen molecule binds to it and circulates approaching the cells, where the exchange of cellular respiration with carbon dioxide takes place.
The name hemoglobin is a compound of two smaller particles: heme and globin. The first part tells us about the nucleus of the molecule made up of the heme group, where iron atoms settle.
The presence of the heme group is part of the explanation for the color change of the bruises, as well as a determining factor in the diagnosis of iron deficiency anemia. This happens when iron is lacking in the body.
Bruises change color in stages
Once trauma has occurred and the bruise or bruise has formed, blood is trapped under the skin. The body will put in place mechanisms to absorb this stagnant substance, since it cannot go outside.
At the beginning the color is red, typical of circulating blood and active hemoglobin. However, outside the vessels, in the hematoma, the hemoglobin is digested by macrophage cells that initiate its digestion and decomposition, causing it to darken.
The dark red bruise is what we see through the skin as violet. It is about the young bruise, just appeared. The days will pass and that violet will turn green, as the decomposition of hemoglobin continues and a new compound appears, which is biliverdin.
Now a change will take place that may go unnoticed, and that is the transformation from green to yellow. E n chemical terms is the biliverdina it becomes bilirubin within the hematoma. From the outside, the bruise changes color, but it also shrinks, so the natural pigmentation of the skin begins to appear.
Bilirubin will be transformed one last time and will give way to hemosiderin. This compound is brownish, with little saturation, and coincides with the almost total reabsorption of accumulated blood. The macrophages engulf the hemosiderin and the skin regains its normal staining.
When to worry?
Bruises change color because this is the process of their resorption. We must be attentive to the chromatic progression, but at the same time we must control that alarm signs do not appear that alert us to an alteration.
There are pathological conditions that complicate the evolution of hematomas, or that cause them to appear without trauma involved. In those cases, a medical consultation is required to evacuate doubts.
In general, the most common causes of abnormal bruising are related to bleeding disorders, such as a lack of platelets or a vitamin K deficiency. These patients also suffer from recurrent bleeding.
The discoloration of bruises is normal in most cases. There is no need to be scared if our bruises go from purple to green or yellow. We just have to make sure that the process is completed, and wait for the skin to return to its usual color.