What diseases have low iron? A comprehensive guide to underlying medical conditions

December 31, 2025 •

4 min read

Chronic iron deficiency is the most common nutrient deficiency in the world, with causes extending far beyond simple dietary insufficiency. A variety of chronic diseases and medical conditions can disrupt iron absorption, increase blood loss, or cause inflammation that interferes with the body's iron regulation. This guide explores the different types of diseases that can lead to depleted iron stores.

Quick Summary

Chronic conditions such as inflammatory bowel disease, chronic kidney disease, and heart failure can all cause low iron levels, often through mechanisms of poor absorption, chronic bleeding, or inflammation. Some cancers, thyroid disorders, and malabsorption diseases like celiac are also major contributors. Identifying the underlying medical cause is crucial for effective treatment.

Key Points

Malabsorption is a Major Cause: Conditions like celiac disease, H. pylori infection, and bariatric surgery can prevent proper iron absorption, regardless of dietary intake.
Chronic Bleeding is a Common Culprit: Diseases that cause slow, persistent blood loss, such as inflammatory bowel disease, peptic ulcers, and colorectal cancer, are significant causes of low iron.
Chronic Inflammation Locks Up Iron: In conditions like chronic kidney disease (CKD) and heart failure, inflammation increases a hormone that traps iron in storage, creating a 'functional' iron deficiency.
Hypothyroidism Affects Absorption: An underactive thyroid can lead to a decrease in iron absorption, contributing to low iron levels and exacerbating fatigue.
Root Cause Investigation is Essential: Because symptoms are non-specific, identifying and treating the underlying disease is critical for correcting iron deficiency, as supplementation alone may be insufficient.

Malabsorption Disorders

Many conditions interfere with the small intestine's ability to absorb iron from food, regardless of dietary intake. The most prominent example is celiac disease, an autoimmune disorder where consuming gluten damages the lining of the small intestine, impairing nutrient absorption, including iron. This damage can occur even without typical digestive symptoms, with iron deficiency being the primary indicator.

Other malabsorption issues and infections include:

Atrophic Gastritis: This condition involves chronic inflammation of the stomach lining, leading to a loss of gastric acid-producing cells. Stomach acid is vital for converting non-heme iron into a more absorbable form.
Helicobacter pylori Infection: The bacterium H. pylori, which can cause stomach ulcers and gastritis, is known to interfere with iron metabolism and lead to deficiency.
Bariatric Surgery: Procedures that alter the stomach and small intestine, such as gastric bypass, can significantly reduce the surface area available for iron absorption.
Crohn's Disease: A type of inflammatory bowel disease (IBD), Crohn's can affect any part of the digestive tract, and inflammation in the duodenum can directly impair iron absorption.

Chronic Blood Loss Conditions

For adults, particularly men and postmenopausal women, gastrointestinal (GI) bleeding is a leading cause of iron deficiency. This bleeding can be subtle and go unnoticed for long periods, slowly draining the body's iron stores. Common causes of chronic blood loss include:

Inflammatory Bowel Disease (IBD): Both Crohn's disease and ulcerative colitis involve chronic inflammation of the intestines. Ulcerations and bleeding from the inflamed bowel lining are frequent causes of iron loss.
Peptic Ulcers: Bleeding from stomach or duodenal ulcers is another significant source of chronic blood loss.
Gastrointestinal Cancers: Colorectal cancer is a particularly insidious cause, as a tumor can bleed slowly over time, with iron deficiency often being an early warning sign. Other GI cancers can also cause bleeding.
Regular NSAID Use: Long-term use of nonsteroidal anti-inflammatory drugs like ibuprofen and aspirin can irritate the stomach lining, leading to chronic, low-level blood loss.

Anemia of Chronic Disease and Inflammation

In chronic diseases, systemic inflammation causes the body to sequester iron within its storage sites, making it unavailable for red blood cell production. This leads to a condition called 'anemia of chronic disease' or 'anemia of inflammation'. This is a key reason why iron deficiency in these patients is often 'functional', meaning iron stores exist but are locked away.

Common conditions in this category include:

Chronic Kidney Disease (CKD): Patients with CKD often have iron deficiency due to blood loss (especially during dialysis), poor dietary absorption, and an inflammatory state that increases hepcidin. Elevated hepcidin levels block iron release from stores.
Heart Failure: Iron deficiency is a common comorbidity in heart failure and is an independent predictor of worse outcomes, even without concurrent anemia. The condition causes chronic inflammation and congestion that can lead to malabsorption.
Cancer: Beyond bleeding, cancer itself can cause inflammation that suppresses red blood cell production in the bone marrow and disrupts iron metabolism.
Autoimmune Disorders: Diseases like rheumatoid arthritis can trigger chronic inflammation that affects iron availability, contributing to anemia.

Other Disease-Related Causes

Hypothyroidism: An underactive thyroid can slow down many metabolic processes, including the production of stomach acid and the absorption of iron. The fatigue associated with both conditions can make it difficult to differentiate symptoms.
Pregnancy: Though not a disease, the increased demand for iron to support fetal growth puts significant strain on a pregnant person's iron stores, often leading to deficiency.
Rare Genetic Conditions: Inherited disorders like iron-refractory iron deficiency anemia (IRIDA) can impair the body's ability to absorb or utilize iron.

Comparing Causes of Low Iron


Cause Category	Mechanism	Example Conditions	Key Diagnostic Indicators
Malabsorption	Intestinal lining damage or reduced acid production hinders nutrient uptake.	Celiac Disease, H. pylori, Atrophic Gastritis	Positive antibody tests (celiac), endoscopy, breath test (H. pylori)
Chronic Bleeding	Slow, persistent blood loss from the digestive tract or other sources depletes iron over time.	Inflammatory Bowel Disease, Colorectal Cancer, Peptic Ulcers	Blood in stool, endoscopy, unexplained anemia in men/postmenopausal women
Chronic Inflammation	Systemic inflammation increases hepcidin, trapping iron in stores and blocking its use for red blood cell production.	Chronic Kidney Disease, Heart Failure, Rheumatoid Arthritis	High ferritin (despite low iron availability), high inflammatory markers like CRP

The Importance of Diagnosis

Because the causes of low iron are so varied and the symptoms often non-specific, it is crucial to work with a healthcare provider to pinpoint the underlying issue. A simple blood test can reveal low iron levels, but only further investigation can reveal if the cause is diet-related, due to malabsorption, or a symptom of a more serious underlying disease. Effective treatment of the root cause is the only way to ensure long-term resolution of iron deficiency.

For example, treating celiac disease with a gluten-free diet can heal the intestinal lining and restore normal iron absorption. In cases of heart failure or CKD, intravenous iron may be required to overcome the body's inflammatory block on iron metabolism. For those with chronic bleeding, endoscopic procedures may be necessary to identify and treat the source. Simply taking oral iron supplements may not be enough, especially if the body cannot absorb it or a chronic disease is trapping it away.

In conclusion, low iron is not always a simple nutritional problem. It can be a critical sign of a much larger, and potentially more serious, medical issue. Recognizing that diseases affecting the GI tract, kidneys, heart, and thyroid can all lead to depleted iron levels is the first step toward a proper diagnosis and effective treatment plan. The interconnectedness of bodily systems means that a seemingly minor symptom like fatigue could be a clue to uncovering a chronic, underlying disease. If you suspect a problem, consult a medical professional for a thorough investigation.

For further reading on the complex relationship between chronic diseases and iron metabolism, the NCBI Bookshelf provides detailed reviews such as this one on chronic iron deficiency: Chronic Iron Deficiency - StatPearls - NCBI Bookshelf.

Frequently Asked Questions

Iron deficiency means your body's iron stores are low. If the deficiency becomes severe enough to affect the production of red blood cells, it progresses to iron deficiency anemia, which is characterized by a low red blood cell count and low hemoglobin.

Yes. Iron deficiency can be the only presenting symptom of celiac disease, even without digestive issues like diarrhea. The damage to the small intestine, where iron is absorbed, directly causes the deficiency.

CKD causes low iron through several mechanisms, including blood loss (especially during dialysis) and chronic inflammation. This inflammation increases a hormone called hepcidin, which traps iron in storage and prevents it from being used for red blood cell production.

Not all cancers directly cause low iron, but it is common. Cancers that affect bone marrow, cause chronic bleeding (like colorectal cancer), or induce inflammation can all lead to iron deficiency or anemia of chronic disease.

Yes. Severe iron deficiency anemia forces the heart to work harder to circulate blood and oxygen, which can lead to an enlarged heart, heart failure, or irregular heartbeats. In heart failure patients, iron deficiency is independently associated with worse outcomes.

Oral iron may be ineffective if you have a malabsorption disorder like celiac disease, ongoing chronic bleeding, or an inflammatory condition that blocks iron utilization. Intravenous iron is often the more effective treatment in such cases.

Common symptoms include fatigue, weakness, pale skin, shortness of breath, headache, dizziness, cold hands and feet, brittle nails, and restless legs syndrome.