Anemia

Anemia is a widespread blood disorder that reduces the body's ability to transport oxygen. Oxygen is essential for providing energy to all living tissues. This reduction in oxygen capacity occurs through three main pathways. A person may have a low number of red blood cells. They may have a low amount of hemoglobin, which is the protein that carries oxygen. Or, the hemoglobin itself may have abnormalities that prevent it from working correctly.

To understand how this works, we must look at how the body maintains its blood supply. This process is called erythropoiesis. In healthy adults, stem cells in the red bone marrow mature into red blood cells over about seven days. The body is incredibly busy, producing between 2 and 3 million new red blood cells every single second. These cells live for about 100 to 120 days as they circulate through the body. Eventually, the cells age and change. This makes them easy for the spleen to recognize so they can be broken down. This breakdown process is called eryptosis. In a healthy system, the rate of production matches the rate of breakdown to keep the population balanced.

Anemia is categorized by the physical characteristics of the red blood cells. Doctors look at the size of the cells and the amount of hemoglobin they contain. If the cells are smaller than normal, the condition is called microcytic anemia. If the cells are larger than normal, it is called macrocytic anemia. When the cells are of a normal size, it is referred to as normocytic anemia.

These classifications help medical professionals determine the underlying cause of the disorder.

There are several distinct ways that anemia can develop. One cause is decreased production, where the bone marrow cannot make enough cells. This can happen due to iron deficiency or a lack of folate and vitamin B12. It can also be caused by bone marrow tumors or kidney failure, which reduces the hormone erythropoietin. Another cause is increased breakdown, known as hemolytic anemia. This occurs when red blood cells are destroyed faster than they are made, often due to infections like malaria or genetic disorders like sickle cell anemia.

Finally, anemia can be caused by blood loss from surgery, injury, or menstruation.

Symptoms vary depending on how quickly the anemia develops. If anemia is chronic, meaning it comes on slowly, the body may adapt. Symptoms might be vague, such as tiredness, weakness, or headaches. A person might also notice pale or yellowish skin, or even spoon-shaped nails in cases of iron deficiency.

If the anemia is acute, meaning it happens very fast, the symptoms are much more severe. This can include confusion, rapid heartbeat, low blood pressure, and even loss of consciousness. In severe cases, the heart may work much harder to compensate, leading to a fast heart rate or chest pain.

Anemia is a massive global health issue, affecting between one-fifth and one-third of the world's population. Iron-deficiency anemia is the most frequent cause and impacts nearly one billion people.

This condition is most prevalent in children, the elderly, and women of reproductive age. For example, the prevalence in women aged 15 to 49 rose from 27.6% to 30.7% between 2012 and 2023. In 2013, iron-deficiency anemia caused approximately 183,000 deaths. This was a decrease from 213,000 deaths recorded in 1990.

Because of its impact, anemia is a major focus for international health organizations. It is one of the six World Health Organization global nutrition targets for 2025. Addressing anemia is also linked to the Sustainable Development Goals, specifically SDG 2, which aims to achieve zero world hunger. Medical treatments are highly specific to the cause. While some groups, like pregnant women, may use iron pills for prevention, doctors do not recommend general dietary supplements without a diagnosis. In very severe cases, doctors may use blood transfusions to restore oxygen levels.