Iron Deficiency: Why Ferritin Is More Important Than Haemoglobin

Iron deficiency is the most common nutritional deficiency in the world, affecting an estimated 2 billion people globally. In Ghana, it is endemic — particularly among women of reproductive age, pregnant women, adolescent girls, and young children. Yet despite its prevalence, iron deficiency is routinely missed because the most commonly tested marker — haemoglobin — becomes abnormal only at the late stage of iron deficiency anaemia, after iron stores have been depleted and red blood cell production is already compromised. The earlier, more sensitive marker — serum ferritin — is checked far less frequently.

The Three Stages of Iron Deficiency

Stage 1: Iron Depletion

Iron stores (measured by serum ferritin) are reduced, but circulating iron and haemoglobin remain normal. At this stage there are no anaemia-related symptoms, but subtle effects on cellular function may already be occurring — because iron is not just needed for haemoglobin. It is an essential component of hundreds of enzymes involved in energy metabolism, DNA synthesis, and neurotransmitter production. Ferritin below 30 µg/L (or below 12 µg/L in stricter definitions) defines this stage.

Stage 2: Iron-Deficient Erythropoiesis

Iron stores are exhausted and transport iron (serum iron and transferrin saturation) begins to fall. Red blood cell production becomes iron-limited. Haemoglobin is still in the normal range, but red cells are becoming smaller (falling MCV) and paler (falling MCHC). Symptoms may begin to appear — mild fatigue, reduced exercise tolerance, difficulty concentrating — but they are subtle and easily dismissed.

Stage 3: Iron Deficiency Anaemia

Haemoglobin has fallen below the normal range. The CBC shows microcytic, hypochromic anaemia. Symptoms are more pronounced: significant fatigue, breathlessness on exertion, pallor, headaches, palpitations, and in severe cases, a smooth, painful tongue (glossitis), cracking at the corners of the mouth (angular stomatitis), and brittle, spoon-shaped nails (koilonychia). By this stage, the body has been iron-deficient for months to years.

Why Ferritin Is the Critical Test

Ferritin is the storage protein for iron inside cells. Serum ferritin reflects total body iron stores with good sensitivity. The critical point is that ferritin becomes abnormal at Stage 1 — months to years before haemoglobin changes. A patient with ferritin of 8 µg/L but normal haemoglobin is iron-deficient, is likely symptomatic, and will develop anaemia if not treated. Treating at this stage is faster, requires lower doses of iron, and restores function sooner.

The important caveat: ferritin is an acute phase reactant — it rises with infection and inflammation even when body iron stores are actually depleted. In a patient with concurrent infection, ferritin may appear 'normal' or even elevated despite true iron deficiency. This is why C-reactive protein (CRP) should always be checked alongside ferritin when iron deficiency is suspected in a febrile or unwell patient.

Causes of Iron Deficiency in Ghana

Inadequate Dietary Intake

The bioavailability of dietary iron varies enormously. Haem iron from animal sources (meat, fish) is absorbed at 15–35%. Non-haem iron from plant sources (beans, dark leafy vegetables, fortified cereals) is absorbed at only 2–20%, and absorption is further reduced by phytates (in grains and legumes), polyphenols (in tea and coffee), and calcium. Traditional Ghanaian diets heavy in maize, cassava, and legumes without adequate animal protein are relatively iron-poor from a bioavailability standpoint — particularly for pregnant women and young children with high iron demands.

Menstrual Blood Loss

Every menstrual period involves iron loss. Women with heavy menstrual bleeding (menorrhagia) — defined as blood loss above 80 mL per cycle — can lose 50–200 mg of iron per cycle, often exceeding dietary intake capacity. Heavy periods are common, frequently undertreated, and represent one of the most important and overlooked causes of iron deficiency in Ghanaian women.

Intestinal Parasites

Hookworm infection causes chronic intestinal blood loss that can exceed dietary iron intake even in otherwise well-nourished individuals. In areas of Ghana with high hookworm prevalence, regular deworming alongside iron supplementation is necessary for sustainable anaemia correction.

Pregnancy

Pregnancy increases daily iron requirements approximately threefold. Without supplementation, iron deficiency anaemia is almost inevitable in pregnancy in Ghana. Maternal iron deficiency anaemia increases risks of preterm birth, low birth weight, perinatal mortality, and postpartum haemorrhage. Iron and folic acid supplementation should begin at the first antenatal visit and continue throughout pregnancy.

Treatment

Oral iron supplementation (ferrous sulphate, ferrous gluconate, or ferrous fumarate) is the first-line treatment and is widely available on NHIS. It should be taken on an empty stomach (better absorption) with vitamin C-containing juice (enhances absorption), and separated from calcium, antacids, and tea/coffee. Side effects (nausea, constipation, dark stools) are common and dose-dependent. Intravenous iron infusion is reserved for those who cannot tolerate oral iron, have malabsorption, or require rapid repletion (e.g. late pregnancy, pre-surgery).

�� If you are a woman of reproductive age and have not had a ferritin test, request one. The haemoglobin on your blood count can be normal while your iron stores are dangerously low.

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