Why Is Ferritin Low? Causes That Deplete Iron Stores

Low ferritin is an important laboratory finding that indicates reduced iron stores in the body. The most common causes are blood loss, insufficient dietary iron, periods of increased iron need such as pregnancy and inadequate absorption of iron from the intestines.

Haemoglobin may still be normal when ferritin is low. In this situation, iron stores may have started to decrease even though anaemia has not yet developed. Therefore, a normal complete blood count does not always exclude iron deficiency.

Eating iron-containing foods or using supplements without guidance is not enough to increase ferritin. The reason for the reduction should first be identified, and ongoing blood loss, malabsorption or increased iron requirements should also be addressed.

What Is Ferritin and What Does It Do in the Body?

Ferritin is a protein that allows iron to be stored in the body. It is found in different tissues, particularly the liver, bone marrow and immune system cells. The ferritin level measured in the blood provides information about the body’s available iron reserves.

Iron is part of haemoglobin and is involved in transporting oxygen from the lungs to the tissues. When the body cannot obtain enough iron or regularly loses iron, it first uses the iron stored in its reserves. Ferritin may therefore decrease before haemoglobin falls.

Ferritin is also affected by infection and inflammation. During an inflammatory condition, ferritin may appear normal or high. Results should therefore be assessed together with the complete blood count, transferrin saturation and, when necessary, markers of inflammation rather than ferritin alone.

Are Low Ferritin and Iron Deficiency Anaemia the Same?

Low ferritin and iron deficiency anaemia are related, but they do not describe exactly the same condition. When ferritin decreases, iron stores are reduced, although haemoglobin may remain within the normal range for some time.

If iron loss continues, red blood cell production begins to be affected. Iron deficiency anaemia may develop when haemoglobin falls. The process may progress broadly in the following order:

• Iron stores begin to decrease.
• Ferritin falls.
• Transferrin saturation may decrease.
• The structure of red blood cells may change.
• Haemoglobin falls and anaemia may develop.

The belief that “My haemoglobin is normal, so I do not have iron deficiency” is therefore not always correct. Ferritin may also need to be assessed, particularly in people with fatigue, hair shedding or heavy menstrual bleeding.

Why Does Ferritin Fall?

The causes of low ferritin can be considered under four main groups: Increased iron loss, insufficient dietary intake, increased iron requirements and impaired absorption from the intestines.

When only an iron supplement is used without identifying the cause, ferritin may rise temporarily but fall again because the underlying problem continues.

Low Ferritin Due to Blood Loss

A significant amount of the body’s iron is found inside red blood cells. Regular or unnoticed blood loss may therefore reduce iron stores over time.

The main conditions that may cause blood loss include:

• Heavy or prolonged menstrual bleeding
• Frequent blood donation
• Blood loss after childbirth or surgery
• Stomach or intestinal ulcers
• Haemorrhoids and gastrointestinal bleeding
• Inflammatory bowel disease
• Gastrointestinal bleeding associated with certain painkillers
• Chronic blood loss from the urinary tract or another area

Heavy menstrual bleeding and pregnancy are common causes of iron deficiency. Hidden bleeding from the stomach and intestines may also be investigated, particularly in iron deficiency anaemia without a clear explanation.

Insufficient Dietary Iron

A low-iron and unbalanced diet may contribute to reduced ferritin over time. The risk is not limited to people who do not eat meat; it may also occur in those who consume insufficient calories, follow restrictive diets or have irregular eating patterns.

Nutrition-related risk may increase in the following circumstances:

• Eating few iron-containing foods
• Long-term, unsupervised restrictive diets
• Insufficient protein intake
• Very low-calorie diets
• Regularly drinking tea or coffee with iron-containing meals
• Inadequate nutrition during rapid growth in children and adolescents

The absorption of plant-based iron may be more variable than that of animal-based iron. It is therefore important to consider not only whether a food contains iron but also how the meal is planned.

Increased Iron Requirements

During certain stages of life, the body’s iron needs increase. When dietary iron cannot meet this increase, iron stores may begin to fall.

Iron requirements may increase during:

• Pregnancy
• Breastfeeding
• Rapid growth during childhood and adolescence
• Intensive endurance exercise
• The postpartum period
• Recovery after surgery or illness

Low ferritin during pregnancy may not be explained only by nutrition. Increased blood volume and the greater amount of iron required for the baby’s development also affect the process.

Impaired Intestinal Iron Absorption

Even when a person eats iron-rich foods or uses supplements, sufficient absorption may not occur in the intestines. Ferritin may then fail to rise as expected or decrease again after treatment.

Conditions that may cause malabsorption include:

• Celiac disease
• Crohn’s disease and other inflammatory bowel diseases
• Stomach or small bowel surgery
• Chronic conditions affecting the intestinal surface
• Persistent diarrhoea and nutrient malabsorption
• Certain conditions affecting stomach acid and digestion

When ferritin does not increase despite iron treatment, absorption, adherence and ongoing blood loss should be assessed together before concluding that the supplement does not work.

Which Hidden Conditions Can Lower Ferritin?

Low ferritin is most commonly caused by frequent factors such as nutrition, heavy menstrual bleeding or pregnancy. However, underlying health conditions may be investigated when the reduction is unexplained, recurrent or does not improve despite treatment.

The term “hidden condition” does not mean that a serious disease must be present. The aim is to avoid overlooking a cause that continually reduces iron stores or prevents iron absorption.

Celiac Disease

In celiac disease, the immune response triggered by gluten may damage the surface of the small intestine. Ferritin may fall when the area where iron is absorbed is affected.

Celiac disease does not appear only with diarrhoea, abdominal pain or weight loss. In some people, fatigue and unexplained iron deficiency may be the main findings. When the cause of iron deficiency anaemia is unclear and celiac disease is plausible, assessment may begin with blood tests.

Starting a gluten-free diet without testing may make diagnosis more difficult. When celiac disease is suspected, dietary changes should be planned after medical assessment.

Crohn’s Disease and Ulcerative Colitis

Inflammatory bowel diseases such as Crohn’s disease and ulcerative colitis may cause both intestinal blood loss and impaired nutrient absorption.

A Gastroenterology assessment may be needed when low ferritin is accompanied by abdominal pain, persistent diarrhoea, blood in the stool, weight loss or bowel symptoms that wake the person at night. Intestinal inflammation may be one of the causes of gastrointestinal bleeding.

Stomach Ulcers and Gastrointestinal Bleeding

Small, chronic bleeding in the stomach or intestines may not always be visible. Iron loss may develop over time without obvious blood in the stool.

Gastrointestinal assessment becomes particularly important in men, postmenopausal women or people with iron deficiency anaemia that cannot be explained by heavy menstrual bleeding. Depending on age, symptoms and risk factors, the physician may plan a faecal occult blood test, endoscopy or colonoscopy.

Low ferritin alone does not mean stomach or bowel cancer. However, assessment should not be delayed when the cause is unexplained or when anaemia, weight loss, changes in bowel habits or signs of gastrointestinal bleeding are present.

Helicobacter Pylori Infection

Helicobacter pylori is a bacterium that may cause chronic inflammation in the stomach lining. In some people, it may affect stomach health and iron use, contributing to recurrent iron deficiency.

When the cause of iron deficiency anaemia cannot be identified, a physician may consider Helicobacter pylori testing after the necessary gastrointestinal investigations. Treatment is personalised when the result is positive.

Gynaecological Conditions

Heavy menstrual bleeding should not automatically be accepted as a personal characteristic. Fibroids, adenomyosis, endometrial polyps, hormonal irregularities and certain bleeding disorders may increase menstrual blood loss.

An Obstetrics and Gynaecology assessment may be considered when periods last longer, large clots occur, pads need to be changed during the night or bleeding affects daily life. Iron supplementation may help replace the lost iron, but ferritin may fall again when the cause of the bleeding continues.

What Are the Symptoms of Low Ferritin?

Low ferritin may not cause any symptoms, particularly in the early stages. As iron stores decrease and iron deficiency progresses, complaints affecting daily life may develop.

Common symptoms may include:

• Persistent tiredness and low energy
• Reduced exercise capacity
• Shortness of breath on exertion
• Dizziness
• Headaches
• Palpitations
• Paler skin
• Difficulty concentrating
• Increased hair shedding
• Brittle or altered nails
• Feeling cold
• Restless legs symptoms
• Cravings for non-food items such as ice, soil or paper
• Tenderness of the tongue or corners of the mouth

Fatigue, hair shedding and dizziness are not specific to low ferritin. Thyroid disease, vitamin B12 deficiency, sleep disorders and other health concerns may cause similar symptoms. Iron deficiency anaemia may cause fatigue, shortness of breath, palpitations, headaches and hair loss.

Which Tests Are Assessed When Ferritin Is Low?

A single value should not be used to interpret ferritin results. The physician may assess different laboratory tests together according to the person’s symptoms and medical history.

Frequently reviewed values include:

• Haemoglobin
• Haematocrit
• Red blood cell count
• MCV and MCH
• Serum ferritin
• Serum iron
• Transferrin or total iron-binding capacity
• Transferrin saturation
• CRP or erythrocyte sedimentation rate
• Vitamin B12 and folate
• Faecal occult blood testing when necessary

Because ferritin may increase during infection and inflammation, a normal result may not exclude iron deficiency in every situation. Ferritin, transferrin saturation and inflammation markers should be interpreted together, particularly in people with chronic conditions.

When the cause of iron deficiency is unclear, additional investigations for blood loss and malabsorption may be performed instead of simply repeating laboratory tests. A complete blood count is a basic test in iron deficiency anaemia, and testing for blood in the stool or specialist assessment may be needed when the cause remains unclear.

What Should Be Done to Increase Ferritin Quickly?

The first step in increasing ferritin safely and sustainably is identifying the cause of the deficiency. Taking supplements alone may not restore iron stores permanently while heavy bleeding, an ulcer or malabsorption continues.

Treatment is planned according to the ferritin level, haemoglobin, symptoms, accompanying conditions and whether the person can tolerate iron preparations.

The Cause of the Deficiency Should Be Treated

Ferritin may decrease again after treatment when the source of iron loss has not been identified.

Depending on the cause, the following steps may be considered:

• Assessing heavy menstrual bleeding
• Investigating gastrointestinal bleeding
• Evaluating celiac disease or inflammatory bowel disease
• Correcting nutritional deficiencies
• Reviewing the frequency of blood donation
• Assessing iron requirements during pregnancy and breastfeeding

Understanding why ferritin has fallen is as important as increasing the value.

An Iron-Rich Diet Should Be Planned

Nutrition is important for supporting iron stores, although it may not be sufficient on its own in significant deficiency.

Foods containing iron may include:

• Red meat
• Turkey and chicken
• Fish and seafood
• Eggs
• Lentils, chickpeas and beans
• Dark-green leafy vegetables
• Iron-fortified cereals
• Raisins, dried apricots and prunes
• Pumpkin seeds and sesame

Combining plant-based iron sources with foods containing vitamin C, such as peppers, citrus fruits, tomatoes or lemon, may support absorption. Consuming tea, coffee or large amounts of dairy at the same time as iron-containing meals or supplements may reduce absorption.

Iron Supplements Should Be Used With Medical Guidance

The form, dose and duration of an iron supplement are not the same for everyone. Ferritin and haemoglobin levels, gastrointestinal sensitivity and accompanying conditions should be considered.

Iron tablets may cause the following side effects in some people:

• Constipation
• Diarrhoea
• Nausea
• Abdominal pain
• Heartburn
• Darker stools

People experiencing side effects should consult a physician rather than stopping treatment on their own. The type of preparation, frequency or timing may be changed. The response to iron treatment may be monitored through repeat blood tests.

Does Everyone Need Intravenous Iron?

Intravenous iron is not a routine treatment for everyone who wants to increase ferritin quickly. It may be considered by a physician when oral preparations are not tolerated, absorption is impaired, the deficiency is significant or rapid replacement is medically necessary.

Intravenous iron should be administered in a healthcare setting under medical supervision. The need for treatment is determined according to the overall clinical picture and other results, not ferritin alone.

Why Does Ferritin Not Increase Despite Treatment?

When ferritin does not increase despite supplementation, this does not always mean that treatment has failed. Adherence, dose, absorption and ongoing iron loss should first be reviewed.

Factors that may make it difficult to increase ferritin include:

• Irregular use of the medicine
• Skipping doses because of side effects
• Ongoing heavy menstrual bleeding
• Unnoticed gastrointestinal bleeding
• Celiac disease or inflammatory bowel disease
• Taking iron with tea, coffee or large amounts of calcium
• Iron requirements exceeding the amount being taken
• The need to reassess the diagnosis or laboratory results

A physician should be consulted before increasing the supplement. Uncontrolled iron use may cause unnecessary side effects and excessive iron accumulation.

Which Doctor Should You See for Low Ferritin?

The first assessment for low ferritin may be performed by Internal Medicine or Family Medicine. The physician reviews the blood results together with the person’s medical history and investigates possible causes.

Referral to different specialties may be made according to the cause:

• Obstetrics and Gynaecology for heavy menstrual bleeding
• Gastroenterology for digestive symptoms
• Haematology for unexplained or treatment-resistant anaemia
• Obstetrics and Gynaecology during pregnancy
• Nutrition and Dietetics for dietary planning

An in-person or emergency assessment should be obtained without waiting for a routine appointment when there are black or bloody stools, fainting, chest pain, severe shortness of breath, significant palpitations or rapidly worsening general health.

Plan Your Online Internal Medicine Consultation With Happ Health

Low ferritin should be assessed together with its underlying cause rather than managed only with iron supplementation. Heavy menstrual bleeding, digestive symptoms, nutritional deficiencies and malabsorption may all lead to the same laboratory finding.

Through Happ Health, you can arrange an online doctor consultation and review results such as ferritin, complete blood count, serum iron and transferrin saturation with a physician. When necessary, the physician may plan additional laboratory tests, an in-person examination or referral to the relevant specialty. Happ Health is positioned as a digital healthcare platform offering access to online doctors and different health services.

When nutrition also needs to be assessed, you can plan your daily iron intake and meal pattern according to your personal needs with online dietitian support after the medical consultation.