What Causes Low Hemoglobin? More Than Just Iron Deficiency
Introduction
Hemoglobin is an essential protein contained in red blood cells (RBCs) that transport oxygen from the lungs to body tissues and transport carbon dioxide back to the lungs to be expelled. If hemoglobin decreases below normal, anemia occurs. Anemia is a public health problem that affects more than 1.6 billion individuals, particularly women and children in developing nations.
The majority of individuals correlate low hemoglobin with iron deficiency, and although iron is a key element in the creation of hemoglobin, it's not the sole participant. There are many other factors — nutritional, genetic, physiological, and pathological — that result in low hemoglobin.
In this article, we’ll explore the wide range of causes behind low hemoglobin, diving deep into the lesser-known but equally important reasons that might be overlooked in everyday diagnoses.
Section 1: What is Hemoglobin and Why Is It Important?
Hemoglobin consists of four subunits with a heme group that has the capacity to bind oxygen. The presence of the heme with iron enables hemoglobin to bind reversibly with oxygen in the lungs and to release it in the tissues where it is required.
Normal hemoglobin concentration differs depending on age and sex:
Men: 13.8 – 17.2 g/dL
Women: 12.1 – 15.1 g/dL
Children: 11 – 13 g/dL (age-dependent)
A decline below these levels can cause fatigue, shortness of breath, pale color, dizziness, and in extreme conditions, strain on the heart. Even though iron is the focal point, we also need to look at the whole ecosystem of blood production and upkeep.
Section 2: Iron Deficiency – The Most Common Cause
Iron deficiency anemia (IDA) is actually the global leader in the causes of low hemoglobin. Iron is critical for the production of hemoglobin, and without sufficient amounts of it, the body cannot form sufficient healthy red blood cells.
Causes of Iron Deficiency:
Poor dietary intake: In vegetarians or those with malnutrition
Chronic blood loss: Due to heavy menstrual cycles, gastrointestinal ulcers, or hemorrhoids
Malabsorption: In conditions such as celiac disease or bariatric surgery
Increased demands: Pregnancy, children's growth spurts, or endurance training
Symptoms of Iron Deficiency Anemia:
-Fatigue
-Pale color of the skin
-Restless legs
-Brittle nails
-Cravings for nonfood items (pica)
Treatment usually involves changing diet, taking iron tablets, or addressing the source of bleeding.
But suppose iron isn't the problem. That's where things get complicated.
 |
| image credit: FREEPIK |
Section 3: Beyond Iron — Other Nutritional Deficiencies
Hemoglobin production needs more than iron. A number of other nutrients are important to red blood cell formation and DNA synthesis, and their absence may lead to low hemoglobin.
Vitamin B12 Deficiency
Vitamin B12 is important for DNA synthesis during the manufacture of red blood cells. Deficiency causes megaloblastic anemia, in which red blood cells are large and immature.
Causes:
-Poor diet (particularly in vegans)
-Pernicious anemia (autoimmune destruction of intrinsic factor)
-GI surgery (e.g., gastric bypass)
-Proton pump inhibitor or metformin long-term use
Symptoms:
-Fatigue
-Tingling sensation in hands and feet (neuropathy)
-Confusion (cognitive decline)
-Glossitis (inflamed tongue)
Folate (Vitamin B9) Deficiency
Folate is essential for cell division and growth. Its deficiency also leads to megaloblastic anemia and may also affect pregnant women more intensely.
Causes:
-Unbalanced diet
-Alcoholism
-Certain drugs (e.g., methotrexate, phenytoin)
-Pregnancy (higher demand)
⚡ Other Nutrients:
Copper: Required for iron processing; its deficiency is unusual but can resemble B12 deficiency.
Vitamin A: Regulates iron mobilization and affects red blood cell production
Section 4: Inflammation and Chronic Diseases
At other times, the body has all of the nutrients required but the chronic disease gets in the way of using them properly. Inflammatory illnesses frequently produce a form of anemia called anemia of chronic disease (ACD), or inflammation-related anemia.
How Inflammation Interferes with Hemoglobin
Inflammatory messages can:
-Inhibit production of erythropoietin (EPO) — a hormone secreted by the kidneys that triggers red blood cell manufacturing.
-Trap iron in storage sites, making it unavailable for hemoglobin synthesis.
-Shorten red blood cell survival.
Conditions That Cause Anemia of Chronic Disease:
Chronic kidney disease (CKD): Damaged kidneys reduce EPO secretion.
Autoimmune diseases: Examples include rheumatoid arthritis or lupus.
Infections: Tuberculosis, HIV, and chronic fungal infections.
Cancer: Particularly blood cancers like leukemia, lymphoma, or multiple myeloma.
In ACD, iron supplements alone don't solve the problem — the underlying disease must be treated.
Section 5: Bone Marrow and Blood Disorders
Red blood cells are formed in the bone marrow, so any illness that interferes with the ability of the marrow to make cells can lead to low hemoglobin.
Aplastic Anemia
It is a rare but severe condition where the bone marrow fails to make a sufficient number of new blood cells.
Causes:
-Autoimmune reactions
-Chemotherapy or radiation
-Viral infections (such as hepatitis)
-Exposure to toxins (such as benzene)
Myelodysplastic Syndromes (MDS)
In such disorders, malformed and dysfunctional blood cells are formed by the bone marrow. Prevalent among older individuals, MDS frequently advances to leukemia.
Leukemia and Lymphoma
These blood-forming tissue cancers displace healthy marrow cells, slowing red blood cell production and thus hemoglobin levels.
Thalassemia and Sickle Cell Disease
These genetic blood diseases change hemoglobin structure or production:
Thalassemia results in low hemoglobin levels from decreased globin chain synthesis.
Sickle cell anemia deforms hemoglobin, shortening red blood cell survival and obstructing blood flow.
Section 6: Blood Loss – Overt and Latent
Blood loss is a direct cause of low hemoglobin because it lowers the overall number of circulating red blood cells.
Acute Blood Loss
-Trauma
-Surgery
-Internal bleeding (ruptured aneurysms, postpartum hemorrhage)
Chronic Blood Loss
-Bleeding in the gastrointestinal tract due to ulcers, hemorrhoids, or colon cancer
-Menorrhagia (excessive menstrual bleeding)
-Donation of blood repeatedly
-Parasitic infections (hookworm) in developing nations
At times, the cause of blood loss is occult, and therefore signs such as pallor and fatigue might be the only clues.
Section 7: Medications and Toxic Exposures
Certain toxins and medications may decrease hemoglobin by:
-Inhibiting red blood cell production
-Causing hemolysis (red blood cell destruction)
-Causing internal bleeding
Medications that May Produce Anemia:
NSAIDs (e.g., ibuprofen, naproxen): Can cause GI bleeding
Chemotherapy: Inhibits bone marrow
Antibiotics (chloramphenicol, sulfonamides): Rare marrow suppression
Anticonvulsants and certain HIV drugs
☠️ Toxins:
Lead poisoning interferes with enzymes that are necessary to produce hemoglobin
Benzene (industrial solvents) can destroy bone marrow
Alcoholism stops the formation of red blood cells and blocks folate metabolism
Section 8: Lifestyle and Environmental Factors
Lifestyle and environmental factors may also cause chronically low hemoglobin.
Athlete's Anemia
Endurance athletes (runners, bikers) can develop a mild anemia from:
-Increased plasma volume (dilutes hemoglobin)
-Iron loss through sweat and GI bleeding
-Mechanical disruption of red cells from foot-strike hemolysis
High Altitude
Residing or training at high altitude makes the body temporarily produce more red blood cells, but at first, individuals can experience low oxygen symptoms (like anemia) as the body gets used to it.
Alcohol Abuse
Alcohol suppresses the bone marrow directly and drains nutrients such as folate, resulting in anemia.
Section 9: Special Populations at Risk
Some populations are more susceptible to low hemoglobin because of heightened physiological needs, nutritional deficiencies, or ongoing health issues.
Pregnant Women
-Dilution of hemoglobin concentration by increased blood volume
-Increased need for iron, folate, and B12
-Pregnancy anemia may elevate preterm birth and low birth weight risk
Infants and Young Children
-Increased iron need due to accelerated growth
-Risk of iron deficiency if formula-fed or not supplemented
Elderly Adults
-More prone to chronic illness
-Possibly have malabsorption or poor diets
-Higher risk of gastrointestinal hemorrhage
Section 10: Diagnosis and When to Consult a Doctor
If you notice symptoms such as ongoing tiredness, pallor, or breathlessness, it's necessary to consult a doctor.
Most Important Tests for Diagnosing Low Hemoglobin:
Complete Blood Count (CBC): Hemoglobin and red cell indices
Ferritin and Iron Studies: Determine iron levels and storage
Vitamin B12 and Folate Tests
Reticulocyte Count: Assesses new red blood cell production
Stool Occult Blood Test: For occult GI bleeding
Bone Marrow Biopsy: In marrow disorder suspicion
Accurate diagnosis is important because iron deficiency treatment won't cure it if the cause is B12 deficiency, bone marrow failure, or chronic inflammation.
Conclusion: What Causes Low Hemoglobin
Low hemoglobin is a symptom rather than a disease unto itself. Although iron deficiency is still the most common cause, it is merely one of many elements that make up a very large puzzle. Nutritional deficiency, chronic disease, inherited disorders, and environmental toxins are all contributors.
Grasping the entire spectrum of causes can result in more accurate diagnosis, better treatment, and ultimately better health outcomes. If you're showing symptoms of anemia, don't simply write it off as iron — speak with a healthcare provider and request a thorough workup.
By looking more broadly, we can more effectively address the real underlying causes of low hemoglobin — and rebalance the body from the inside out.
.png)
0 Comments