The Tired Teenager with a Normal CBC

Interpretation: Microcytic hypochromic anaemia (Hb 10.4, MCV 72) with a low ferritin (9 ng/mL) and normal CRP - ferritin is an acute-phase reactant, so a normal CRP makes the low value trustworthy and effectively diagnostic of iron deficiency. Celiac serology negative and TSH normal exclude the two common alternative causes of microcytosis in adolescents.

Diagnosis: Iron-deficiency anaemia with two additive drivers:

1. Menorrhagia - changing pads every 2 hours on heavy days is objectively heavy menstrual bleeding; at 15 this is the dominant loss.
2. Low dietary iron bioavailability - tea polyphenols chelate non-haem iron; drinking tea with meals can reduce absorption substantially. This is a modifiable contributor, not the sole cause.

Explanation to family: "Her red cells are small because they were built without enough iron - like bricks made with too little mortar. She is losing iron through heavy periods faster than diet can replace it, and tea at meals blocks some of what she does eat."

Do not label this as 'just teenage fatigue' - the ferritin is the anchor.

Transfusion: Not indicated. Hb 10.4 with a stable, asymptomatic (other than fatigue) adolescent and no cardiorespiratory compromise does not meet transfusion thresholds. Transfusion is reserved for symptomatic severe anaemia (generally Hb <7 g/dL), haemodynamic instability, or active ongoing loss. Explain that transfusion would treat the number, not the cause, and carries risk.

Plan:

• Oral iron: elemental iron ~65 mg once daily (alternate-day dosing is increasingly favoured for absorption and tolerability). Counsel on GI side effects, taking on an empty stomach, and avoiding tea/coffee/calcium within 1-2 hours.
• Dietary counselling: iron-rich foods (red meat, legumes, fortified cereals), pair with vitamin C, move tea away from meals.
• Address the menorrhagia: this is the root cause. Discuss with the patient (alone, confidentiality permitting) - consider a hormonal option such as a combined oral contraceptive or LNG-IUS depending on acceptability, and screen for bleeding disorders (e.g., von Willebrand disease) given heavy bleeding since menarche.
• Recheck FBC and ferritin at ~4-8 weeks to confirm response (expect Hb rise ~1 g/dL/month).
• Safety-net: return if worsening breathlessness, palpitations, or syncope.

Escalate to haematology/gynaecology if no response despite adherence - that would suggest ongoing loss or malabsorption.

Use a structured shared-decision approach rather than a flat refusal:

1. Explore her concern - likely fear of her daughter underperforming or being unwell at a major event. Acknowledge it explicitly.
2. Explain the evidence in plain terms - transfusion does not improve athletic performance at this Hb, carries transfusion reactions, alloimmunisation and infection risk, and would not correct the underlying iron deficit; oral iron will raise Hb meaningfully within 3-4 weeks, which fits the timeline.
3. Offer a concrete compromise - start iron today, bring the 4-week blood test forward, and agree a specific review date before the event; if Hb has not improved or she becomes symptomatic, reassess.
4. Respect autonomy while maintaining the recommendation - document the discussion. If she remains insistent, involve a senior clinician; the patient's own assent matters too, and the 15-year-old's views should be sought.
5. Document the rationale, the risks explained, and the agreed plan.

This tests whether you can hold a clinically correct line without becoming adversarial - the exam rewards explicit exploration of the parent's concern and a documented safety-net.