Background: A blood spot is a drop of blood originating from outside the body that hits a surface and undergoes a drying process and changes color over time. This color change process takes place between the 1st hour to the 48th hour. After that time, the color of the blood spots will not change again. This process is caused by the oxidation of HbO2 molecules to methemoglobin, then methemoglobin will undergo a hemichrome process which results in decomposition and denaturation of blood spots. Methods: An experimental study with a factorial time-series design that observed and assessed the color changes of blood spots in adult humans with normal hemoglobin levels based on the Natural Color System (NCS) color standard card, with a sample of all P3D students of the Faculty of Medicine, Malahayati University with hemoglobin levels below normal and meet the inclusion and exclusion criteria, carried out by taking two drops of the blood of the research subject from the tip of the middle finger, dripping on the ceramic and comparing the color changes that occur at the 1st hour, 2nd hour, 3rd hour, 4th hour , 5th hour, 6th hour, 7th hour, 8th hour, 10th hour, 12th hour, 24th hour, 48th hour, using the Natural Color Color Standard Card comparison tool System (NCS) Result: The process of changing the color of the bloodstains occurred at the 1st hour to the 6th hour, while at the 6th hour to the 48th hour, the color of the blood spots did not change color anymore. This is evidenced by the color code that appears at the 6th hour to the 48th hour, namely the NCS S 8502-R color code as much as 87%. This process is caused, because the oxyhemoglobin (HbO2) contained in blood spots with less hemoglobin levels below normal, so that the decomposition process or this oxidation process will take place more quickly. Initially, the HbO2 molecule will turn into methemoglobin, then methemoglobin will undergo a hemichrome process which results in the decomposition and denaturation of the blood spots. Conclusion: The process of changing the color of the blood spots occurs at the 1st hour to the 6th hour, while at the 6th hour to the 48th hour, the color of the bloodspot does not change color anymore. This is evidenced by the color code that appears at the 6th hour to the 48th hour, namely the NCS S 8502-R color code as much as 87%.

age blood spots

natural color system (NCS)

hemoglobin levels below normal

color change