The 14-year-old with fatigue, menorrhagia and a 'normal' haemoglobin
A 14-year-old girl presents with 6 months of fatigue and breathlessness on climbing stairs. Her periods began at 12 and are heavy, lasting 7 days with clots, and she uses 10 pads a day at worst. She is a fussy eater and drinks about 1.5 L of milk a day but eats little red meat. She is pale, with angular stomatitis and spoon-shaped nails. Haemoglobin is 104 g/L, MCV 72 fL, MCH 22 pg, ferritin 6 µg/L, platelets 420 × 10⁹/L, white cell count 6.2 × 10⁹/L. Coeliac serology is negative. She is keen to start on oral iron but her mother is worried about constipation and staining of teeth.
1. Interpret the blood results and explain the thrombocytosis.
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The picture is a microcytic hypochromic anaemia with iron deficiency: low MCV (72 fL) and MCH (22 pg), and a ferritin of 6 µg/L, which is diagnostic (ferritin <15 µg/L is highly specific; <30 µg/L with inflammation is suggestive).
- Ferritin is an acute-phase reactant, so a normal ferritin does not exclude deficiency in inflammation; here it is frankly low, so the diagnosis is secure.
- The thrombocytosis (420 × 10⁹/L) is a reactive phenomenon: iron deficiency increases megakaryopoiesis, and platelets typically normalise after iron repletion. It is not a primary marrow disorder and does not require aspirin or investigation for essential thrombocythaemia in this context.
- The likely cause is menorrhagia compounded by low dietary iron. In an adolescent with heavy periods, always consider an underlying bleeding disorder (e.g. von Willebrand disease) - ask about bleeding after dental extraction, easy bruising, and family history, and consider testing if the history is suggestive.
Coeliac serology is negative, which makes malabsorption less likely, but the history of a restricted diet should be explored.
2. How would you prescribe iron, and how would you address the mother's concerns?
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Prescription: oral ferrous salt (e.g. ferrous sulphate or fumarate) at 3–6 mg/kg/day of elemental iron, once daily. Once-daily dosing is preferred over divided doses because hepcidin rises after a dose and blocks further absorption for ~24 hours.
Counselling points:
- Take with vitamin C (e.g. a glass of orange juice) and on an empty stomach where tolerated; avoid tea, coffee, milk and calcium supplements at the same time, as these inhibit absorption.
- Teeth staining is a real concern with liquid preparations; advise drinking through a straw and rinsing, or use a tablet formulation if she can swallow them. Tablets avoid the staining issue.
- Constipation and dark stools are expected; advise adequate fluid and fibre. If intolerance is severe, switch to an alternative salt or a lower dose taken with food (accepting reduced absorption).
- Expect a reticulocyte response in 1–2 weeks and a haemoglobin rise of about 10–20 g/L over 3–4 weeks. Continue iron for 3 months after the haemoglobin normalises to replenish stores.
- Investigate the cause: refer to gynaecology for menorrhagia management if it persists, and consider a bleeding-disorder screen. Address the diet with dietetic input.
- Warn about iron overdose - keep tablets out of reach of younger siblings.
3. At review 4 weeks later the haemoglobin has risen only to 108 g/L and she remains symptomatic. What is your differential and next step?
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A blunted response suggests either non-adherence, ongoing blood loss, malabsorption, or a second diagnosis.
- Adherence and administration - ask directly and non-judgementally how many doses she actually takes, and whether she takes it with milk or tea. This is the commonest explanation.
- Ongoing loss - menorrhagia may be worsening; quantify again and refer to gynaecology. Consider a bleeding-disorder screen (von Willebrand studies, platelet function) if not already done.
- Malabsorption - coeliac serology was negative, but consider IgA deficiency (which makes tTG-IgA falsely negative - check total IgA), and consider H. pylori or giardiasis. If suspicion persists, duodenal biopsy may be warranted.
- Wrong diagnosis - reconsider thalassaemia trait (microcytosis out of proportion to anaemia, normal ferritin, target cells, family history) - the ferritin here was low, so iron deficiency was real, but a dual diagnosis is possible. Also consider anaemia of chronic disease if there is inflammation.
Next step: repeat full blood count with reticulocyte count and ferritin, review the blood film, check adherence, and re-quantify menstrual loss. If ferritin remains low despite supervised therapy, investigate malabsorption and consider parenteral iron (IV iron is effective and avoids adherence issues) - but only after excluding ongoing uncontrolled loss.