Hypochromia describes a condition where red blood cells (RBCs) appear paler than normal when viewed under a microscope due to insufficient hemoglobin. Hemoglobin is the protein responsible for transporting oxygen throughout the body and imparts the characteristic red color to blood. A finding of hypochromia usually comes from a Complete Blood Count (CBC), a common blood test that provides a detailed look at the components of the blood. The presence of hypochromia indicates that the blood’s capacity to deliver oxygen to tissues and organs is reduced, which can lead to various physical symptoms.
How Hypochromia is Identified on a Blood Test
Hypochromia is identified using red blood cell indices from the CBC test, primarily the Mean Corpuscular Hemoglobin (MCH) and the Mean Corpuscular Hemoglobin Concentration (MCHC). MCH measures the average absolute weight of hemoglobin in a single red blood cell, while MCHC measures the average concentration of hemoglobin relative to the cell’s volume. A result is considered hypochromic when MCH falls below the normal adult reference range of 27–33 picograms per cell, or MCHC drops below 33–36 grams per deciliter. The MCHC is considered the more reliable parameter for confirming hypochromia because it accounts for the size of the cell in its calculation. A low MCHC often suggests that the red cells are also smaller than usual, a condition known as microcytosis.
Primary Causes of Hypochromia
The underlying cause of hypochromia is a defect or deficiency that impairs the body’s ability to produce adequate hemoglobin. The most common cause globally is Iron Deficiency Anemia (IDA), which occurs when the body lacks sufficient iron, a metal that is an indispensable component of the hemoglobin molecule. This deficiency results from inadequate dietary intake, poor absorption due to gastrointestinal issues, or chronic blood loss, such as from heavy menstrual periods or internal bleeding. When iron is scarce, the synthesis of functional hemoglobin is severely restricted, leading to the production of pale, smaller red blood cells.
Another significant cause is Thalassemia, a group of inherited blood disorders that affect the production of the globin chains necessary for hemoglobin structure. These genetic mutations lead to a reduced synthesis rate or an imbalance in the ratio of globin chains, resulting in defective and unstable hemoglobin. Unlike IDA, thalassemia involves a problem with the protein structure itself, rather than a lack of iron, and patients often have normal or high iron stores.
A less common cause is Sideroblastic Anemia, which involves a failure to incorporate iron into the heme molecule, even when iron is present. This defect causes iron to build up within red blood cell precursors in the bone marrow, forming characteristic ringed sideroblasts. This condition can be inherited, such as X-linked sideroblastic anemia, or acquired through factors like lead poisoning, excessive alcohol use, or certain nutritional deficiencies like Vitamin B6. In these cases, the iron is effectively trapped and cannot be used to make functional hemoglobin.
Related Symptoms and Further Diagnostic Steps
Reduced oxygen transport resulting from hypochromia manifests in generalized symptoms associated with anemia. Patients commonly report persistent fatigue and weakness due to insufficient oxygen reaching muscles and organs. Other noticeable symptoms can include:
- Pale skin, often visible in the inner lower eyelids.
- Shortness of breath, especially during minimal exertion.
- Dizziness or headaches.
- Brittle, spoon-shaped nails.
After a CBC reveals hypochromia, further diagnostic tests are necessary to pinpoint the underlying cause. The next step involves an iron panel, measuring serum ferritin, serum iron, and total iron-binding capacity. Low ferritin levels, which indicate the body’s iron storage, are highly specific for Iron Deficiency Anemia. If iron studies are normal or elevated, the focus shifts to ruling out genetic conditions like Thalassemia using hemoglobin electrophoresis or high-performance liquid chromatography. If these initial tests are inconclusive, a bone marrow examination may be required to look for ringed sideroblasts, confirming Sideroblastic Anemia.
Treatment Strategies for Underlying Conditions
Treatment focuses entirely on correcting the specific underlying condition identified through diagnostic testing.
Iron Deficiency Anemia (IDA)
The primary approach for IDA is oral iron supplementation, often using ferrous sulfate. This therapy continues for several months after the anemia resolves to ensure iron stores are fully replenished. Addressing the source of blood loss, such as treating a gastrointestinal ulcer or managing heavy menstruation, is also a mandatory part of the treatment plan.
Thalassemia
Managing Thalassemia requires a different strategy since the body is not iron-deficient, and unnecessary iron intake can be harmful. Milder forms usually require careful monitoring and genetic counseling. More severe forms may necessitate regular blood transfusions, which then require chelation therapy to prevent iron overload from the transfused blood.
Sideroblastic Anemia
Patients with Sideroblastic Anemia may respond to a trial of high-dose Vitamin B6 (pyridoxine) supplementation, particularly in the X-linked congenital form. Pyridoxine helps the body utilize iron more effectively in heme creation. For acquired forms, treatment involves removing the causative agent, such as discontinuing a specific medication or treating lead poisoning.