A woman may feel chronically fatigued and yet receive lab results that her doctor calls “normal.” The enigma almost always has an answer: ferritin. This protein, responsible for storing iron in the body, is one of the most important markers and, at the same time, one of the most underestimated in women's health care.

Low ferritin often manifests itself through multiple symptoms: persistent fatigue, dizziness, shortness of breath, difficulty concentrating, low mood, brittle nails and hair loss.

These signs are often subtle and may be attributable to stress or hormonal changes, making them difficult to identify.

What is ferritin?

Ferritin is a globular protein present in almost all cells in the body - mainly in the liver, spleen, bone marrow and muscles - whose primary function is to capture and store iron in a non-toxic way to release it according to the body's needs. In simple terms, it acts as the body's iron “reservoir”: when the supply is plentiful, it fills that reservoir; when it is scarce, it empties it.

A small amount of ferritin circulates in the blood and can be measured by a simple clinical test. This serum value constitutes the most faithful reflection of the total iron reserves in the body, long before the classic symptoms of anemia appear. Hence its enormous diagnostic value.

Why are women more vulnerable?

Female biology subjects women to regular iron losses that men do not experience. Menstruation represents the main cause: according to the World Health Organization (WHO), iron deficiency affects almost 30% of the world's population, and women of reproductive age constitute the highest risk group.

During pregnancy, the demand for iron multiplies: the fetus and placenta require significant reserves, and low maternal ferritin has been associated with preterm birth, low birth weight, and increased risk of postpartum depression. The breastfeeding period imposes, in turn, additional demands. And in menopause, although menstrual losses cease, an accumulated deficit may persist that requires correction.

Added to these factors are vegetarian or vegan diets without adequate supplementation, gastrointestinal disorders that prevent iron absorption (such as celiac disease or irritable bowel syndrome) and abundant or irregular menstrual cycles that do not always receive due attention.

The mistake of looking only at hemoglobin

One of the most common mistakes in clinical practice is diagnosing iron health solely through hemoglobin—the oxygen-carrying protein in red blood cells. Classic anemia, defined by low hemoglobin, appears at a late stage: the body has already exhausted its ferritin reserves before hemoglobin falls. This means there is a window—sometimes months or years—in which the woman is experiencing real symptoms with seemingly normal baseline tests.

Reference ranges have also been the subject of debate. Some laboratories establish values ​​as low as 12 µg/L as the lower limit of serum ferritin, a threshold considered insufficient by many specialists. Recent research suggests that symptoms may occur at levels below 30 µg/L, and that for optimal function—especially in terms of energy, thyroid function, and hair loss—many women need values ​​above 50–70 µg/L.

A marker for a lifetime

Ferritin is not just an issue of childbearing age. In adolescence, when growth and the first menstrual cycles converge, iron stores can drop rapidly. In perimenopause, irregular and heavy bleeding is especially treacherous. And in the elderly, the impoverished diet and lower intestinal absorption cause the deficit to reappear.

For this reason, more and more scientific societies recommend including serum ferritin in women's annual routine tests, in the same way that cholesterol or blood glucose are controlled. The cost of the exam is minimal; The cost of ignoring it, in quality of life, can be enormous.

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