A 30-year-old woman presents with fatigue, dizziness, shortness of breath, and brittle nails; blood tests show low haemoglobin and low ferritin. What is the most likely diagnosis?

• A. Dehydration
• B. Vitamin B12 deficiency
• C. Iron deficiency anaemia
• D. Aplastic anaemia

Answer: (C)

Iron deficiency anemia is diagnosed when there is anemia with depleted iron stores, reflected by a low ferritin level. Ferritin stores iron in the body, so when those stores are exhausted, ferritin falls. The combination of fatigue, dizziness, shortness of breath, and brittle nails fits iron deficiency, and the lab pattern of low haemoglobin with low ferritin is classic. This is especially common in young women due to menstrual iron loss.

Vitamin B12 deficiency would usually cause a macrocytic (larger-than-normal red cells) anemia and may have neurological signs, with ferritin not characteristically reduced. Dehydration can affect fluid status and hemoconcentration but does not cause low ferritin or a true iron-deficiency pattern. Aplastic anemia presents with pancytopenia and a hypocellular marrow, not specifically with low ferritin reflecting iron stores.