In an otherwise healthy 25‑year‑old female with easy bruising, syncopal episodes, dyspnea, tachycardia, iron‑deficiency anemia and vitamin B12 deficiency, after ruling out malabsorption, leukemia, hypercoagulability and cardiac disease, what is the most likely underlying cause?

Most Likely Underlying Cause

In this 25-year-old woman with easy bruising, syncope, dyspnea, tachycardia, combined iron and B12 deficiency after excluding malabsorption, leukemia, hypercoagulability and cardiac disease, the most likely diagnosis is von Willebrand disease (VWD) with secondary nutritional deficiencies from chronic menorrhagia. 1

Clinical Reasoning

Why Von Willebrand Disease Is the Leading Diagnosis

VWD is the most common inherited bleeding disorder, affecting up to 1% of the population and occurring equally in males and females. 1 The constellation of easy bruising, syncope from blood loss, and dual nutritional deficiencies points strongly toward chronic occult bleeding as the unifying mechanism.

Heavy menstrual bleeding is the hallmark presentation of VWD in reproductive-age women and directly causes both iron and B12 depletion through chronic blood loss. 1, 2 Each menstrual cycle removes approximately 30-40 mg of iron and measurable B12, and when bleeding is excessive (>80 mL per cycle), stores become progressively depleted despite adequate dietary intake. 2

The syncope, dyspnea, and tachycardia are explained by symptomatic anemia from dual deficiency rather than a primary cardiac etiology. 2, 3 Iron-deficiency anemia causes these cardiovascular symptoms through reduced oxygen-carrying capacity, while B12 deficiency can produce similar manifestations through megaloblastic anemia. 4, 5

Supporting Evidence for VWD

Easy bruising with normal platelet count is characteristic of VWD, where deficient or dysfunctional von Willebrand factor impairs platelet adhesion at sites of vascular injury. 1 The 2008 NHLBI guidelines specifically identify easy bruising, mucosal bleeding (including heavy menstrual bleeding), and nosebleeds as cardinal features of Type 1 VWD, which accounts for approximately 75% of symptomatic cases. 1

Importantly, standard coagulation screening (PT, aPTT) may be normal in mild-to-moderate VWD, particularly Type 1, because factor VIII levels are often only mildly reduced. 1 This explains why the condition can remain undiagnosed despite multiple medical evaluations.

Why Nutritional Deficiencies Are Secondary, Not Primary

The exclusion of malabsorption makes primary gastrointestinal causes of B12 and iron deficiency unlikely. 1, 5 Conditions such as celiac disease, inflammatory bowel disease, atrophic gastritis, and post-bariatric surgery anatomy have been ruled out. 1, 6, 5

Dietary inadequacy alone rarely causes combined iron and B12 deficiency in a 25-year-old woman in a high-income country unless she is a strict vegan, which would have been identified in the history. 6, 5 Even vegans typically develop isolated B12 deficiency rather than combined deficiencies. 5

Medication-induced deficiency (metformin >4 months, PPIs >12 months) should have been identified during the workup. 7, 5 The absence of these risk factors further supports chronic blood loss as the mechanism.

Diagnostic Algorithm

Initial VWD Screening (Per 2008 NHLBI Guidelines)

1. Obtain a structured bleeding assessment using the three preoperative screening questions: 1

   • Have you or a blood relative ever had prolonged bleeding from trivial wounds lasting >15 minutes or recurring spontaneously during the 7 days after the wound?
   • Have you ever had heavy, prolonged, or recurrent bleeding after surgical procedures such as tonsillectomy?
   • Have you ever had bruising with minimal or no apparent trauma, especially if you could feel a lump under the bruise?

2. If any answer is positive, proceed to the nine-question detailed bleeding history (Box 1 in NHLBI guidelines) focusing on: 1

   • Menstrual bleeding patterns (duration >7 days, flooding, clots >1 inch, need for double protection)
   • Epistaxis requiring medical attention or cauterization
   • Gastrointestinal bleeding
   • Dental extraction bleeding
   • Postpartum hemorrhage
   • Family history of bleeding disorders

First-Line Laboratory Testing for VWD

Order the following tests simultaneously (do not wait for sequential results): 1

• VWF antigen (VWF:Ag) – measures total VWF protein
• VWF activity (VWF:RCo or VWF:GPIbM) – measures functional VWF
• Factor VIII activity – often reduced in VWD because VWF stabilizes FVIII
• Complete blood count – to quantify anemia severity
• ABO blood group – Type O individuals have 25-30% lower VWF levels than non-O

Critical timing consideration: VWF levels can be falsely elevated by stress, inflammation, pregnancy, or estrogen use. 1 If initial testing is borderline-normal but clinical suspicion remains high, repeat testing after 2-4 weeks or during menses when VWF levels are lowest. 1

Interpretation of VWF Testing

• VWF:Ag <30 IU/dL and VWF activity <30 IU/dL: Definite VWD – refer to hematology 1
• VWF:Ag 30-50 IU/dL or VWF activity 30-50 IU/dL: Possible VWD (especially if Type O blood) – repeat testing and consider hematology referral 1
• VWF:Ag >50 IU/dL and VWF activity >50 IU/dL: VWD unlikely, but consider platelet function disorders if bleeding history is compelling 1

Second-Line Testing if VWD Is Excluded

If VWF testing is normal but bleeding symptoms persist, evaluate for inherited platelet function disorders: 1

• Platelet function analyzer (PFA-100/200) – screening test with limited sensitivity 1
• Light transmission aggregometry – gold standard for platelet function assessment 1
• Platelet flow cytometry – for glycoprotein deficiencies 1

Consider bleeding disorder of unknown cause (BDUC) if all hemostatic testing is normal but bleeding assessment tool score is elevated. 1 These patients may still benefit from hemostatic therapy during procedures. 1

Common Pitfalls and How to Avoid Them

Pitfall 1: Assuming Normal Screening Tests Exclude VWD

Standard PT and aPTT are often normal in Type 1 VWD because factor VIII levels may be only mildly reduced (40-60 IU/dL). 1 The aPTT becomes prolonged only when FVIII falls below 30-40 IU/dL, which occurs primarily in Type 3 VWD. 1

Solution: Always order specific VWF testing (VWF:Ag and VWF activity) in any patient with a positive bleeding history, regardless of normal PT/aPTT. 1

Pitfall 2: Testing During Acute Stress or Inflammation

VWF is an acute-phase reactant and can be falsely elevated during illness, stress, pregnancy, or estrogen use, masking mild VWD. 1 A patient presenting with syncope and tachycardia from acute anemia may have elevated VWF levels that normalize once the acute stress resolves.

Solution: If initial VWF testing is borderline-normal (50-70 IU/dL) but clinical suspicion is high, repeat testing after 2-4 weeks when the patient is clinically stable. 1 Consider testing during menses when VWF levels are physiologically lowest. 1

Pitfall 3: Failing to Recognize Ehlers-Danlos Syndrome (EDS)

Easy bruising with normal hemostatic testing should prompt evaluation for connective tissue disorders, particularly EDS vascular type. 8 EDS causes capillary fragility and perivascular connective tissue weakness, leading to easy bruising without platelet or coagulation abnormalities. 8

Key clinical clues for EDS: 8

• Skin hyperextensibility (can stretch >1.5 cm on forearm)
• Joint hypermobility (Beighton score ≥5/9)
• Atrophic scarring ("cigarette paper" scars)
• Positive Hess test (Rumpel-Leede test) indicating capillary fragility

Solution: Perform a Beighton score examination in any patient with easy bruising and normal hemostatic workup. 1, 8 If hypermobility is present, refer to genetics for EDS evaluation. 8

Pitfall 4: Treating Anemia Without Addressing the Underlying Bleeding Disorder

Replacing iron and B12 without controlling the source of blood loss will result in recurrent deficiency and ongoing symptoms. 1, 2 This patient will continue to lose blood with each menstrual cycle until the bleeding disorder is diagnosed and treated.

Solution: Once VWD is confirmed, initiate hemostatic therapy to reduce menstrual blood loss: 1

• Tranexamic acid 1300 mg three times daily during menses (first-line for menorrhagia in VWD)
• Combined oral contraceptives (increase VWF levels and reduce menstrual flow)
• Desmopressin (DDAVP) 300 mcg intranasal at onset of menses (for Type 1 VWD responsive to DDAVP)

Simultaneously treat the nutritional deficiencies: 1, 5

• Oral ferrous sulfate 325 mg (105 mg elemental iron) once daily or alternate days 1
• Vitamin B12 1000 mcg intramuscularly monthly until stores are repleted, then consider high-dose oral maintenance 5

Pitfall 5: Overlooking Acquired von Willebrand Syndrome (AVWS)

Although less common than hereditary VWD, AVWS should be considered when bleeding symptoms develop in adulthood without a prior personal or family history. 1 AVWS is associated with hypothyroidism, autoimmune disorders, lymphoproliferative disorders, and certain medications. 1

Solution: If VWF levels are low without a family history of bleeding, check TSH (hypothyroidism reduces VWF synthesis), ANA (autoimmune disorders), and review medications. 1, 7 The patient's age (25 years) makes hereditary VWD more likely than AVWS, but autoimmune thyroid disease is common in young women and should be excluded. 7

Immediate Management Steps

1. Transfuse packed red blood cells if hemoglobin <7 g/dL or if symptomatic with cardiovascular compromise (syncope, tachycardia, dyspnea at rest). 1 Target hemoglobin 7-9 g/dL initially. 1

2. Start oral iron replacement immediately (ferrous sulfate 325 mg once daily or alternate days) without waiting for VWD testing results. 1 Expect hemoglobin to rise by at least 1 g/dL within 2 weeks if compliant. 1

3. Administer vitamin B12 1000 mcg intramuscularly immediately if serum B12 <180 pg/mL. 7, 5 Do not wait for methylmalonic acid results when B12 is definitively low. 7

4. Order VWF testing (VWF:Ag, VWF activity, FVIII, ABO blood group) and refer to hematology urgently. 1 Do not delay referral while waiting for test results if bleeding history is compelling. 1

5. Initiate tranexamic acid 1300 mg three times daily during the next menstrual period to reduce blood loss while awaiting hematology evaluation. 1 This is safe and effective even before VWD is confirmed. 1