What is the cause of a 16-year-old male's sleep disturbances, morning bloating, fatigue, pallor, and periorbital darkness, with lab results indicating neutrophilia, leukopenia, and elevated Red Cell Distribution Width (RDW)?

Diagnostic Assessment: Likely Iron Deficiency Anemia with Sleep-Related Symptoms

This patient's presentation is most consistent with iron deficiency anemia (IDA), which explains both the hematologic abnormalities and the constellation of symptoms including fatigue, pallor, periorbital darkness, and potentially the sleep disturbances.

Laboratory Interpretation

The reported values require clarification, as "neutrophils in the mid 40s" and "leukocytes in the low 50s" are abnormally elevated if these represent absolute counts (×10⁹/L). However, if these represent percentages:

• Neutrophils at 40-45% with corresponding lymphocyte reduction would indicate relative neutrophilia with lymphopenia 1, 2
• The RDW of 15.5% (elevated above normal 11.5-14.5%) combined with likely microcytosis strongly suggests iron deficiency anemia 1, 2
• Elevated RDW with low MCV is highly indicative of IDA, as this combination reflects increased variation in red cell size (anisocytosis) characteristic of iron deficiency 3, 1

Primary Diagnosis: Iron Deficiency Anemia

The elevated RDW is the key diagnostic finding that points toward iron deficiency as the underlying problem 1, 2. The clinical manifestations align perfectly with IDA:

• Pallor and periorbital darkness are classic signs of anemia 1, 2
• Profound morning fatigue improving throughout the day reflects the body's compensatory mechanisms and circadian variation in symptom severity 1
• Bloating may relate to gastrointestinal causes of iron loss or malabsorption 3, 2

Confirmatory Testing Required

Serum ferritin is the single most powerful confirmatory test 1, 2:

• Ferritin <30 μg/L confirms iron deficiency in the absence of inflammation 3, 1, 2
• If ferritin is 30-100 μg/L, check transferrin saturation; <20-30% supports iron deficiency 3, 1, 2
• Additional tests: serum iron (low in IDA), total iron binding capacity (increased in IDA) 1

Investigation for Underlying Cause

All patients with confirmed IDA require gastrointestinal evaluation, even adolescents 2:

• Gastrointestinal blood loss is the most common cause in males, including occult bleeding from NSAIDs, gastritis, peptic ulcer disease, or inflammatory bowel disease 1, 2
• Celiac disease should be screened via upper endoscopy with small bowel biopsies (present in 2-3% of IDA patients) 2
• Dietary assessment: Evaluate iron intake, particularly in adolescents with restrictive diets 2
• Medication history: Document any NSAID use, aspirin, or supplements 2
• The morning bloating may indicate underlying gastrointestinal pathology causing both malabsorption and blood loss 3, 2

Sleep Disturbance Connection

The sleep issues are likely secondary to the anemia itself rather than a primary sleep disorder 3:

• Anemia causes fatigue and poor sleep quality through reduced oxygen delivery to tissues 3
• The pattern of feeling worse in the morning and improving by evening is atypical for primary insomnia but consistent with the body's struggle to compensate for anemia overnight 3
• The observation that less sleep correlates with less bloating suggests a gastrointestinal component that worsens with prolonged recumbency 3

Treatment Approach

Initiate oral iron supplementation immediately upon confirming iron deficiency 2:

• A hemoglobin rise ≥10 g/L within 2 weeks confirms the diagnosis even if initial iron studies were equivocal 2
• Continue treatment for 3-6 months after hemoglobin normalizes to replenish iron stores 1, 2
• Recheck complete blood count in 2 weeks to confirm hemoglobin rise 2
• Failure to respond suggests ongoing blood loss, malabsorption, or incorrect diagnosis 2

Critical Pitfalls to Avoid

• Do not dismiss gastrointestinal investigation in a young patient; age does not exclude serious pathology 2
• Combined deficiencies (iron plus B12 or folate) may mask typical findings and normalize MCV despite ongoing deficiency 1
• Anemia of chronic disease can coexist with iron deficiency, particularly in inflammatory conditions like IBD 3, 1
• The white blood cell findings (if truly elevated) could indicate concurrent infection or inflammatory process requiring separate evaluation 4, 5

Immediate Next Steps

1. Order complete iron studies: ferritin, transferrin saturation, serum iron, TIBC 1, 2
2. Obtain complete blood count with indices to confirm MCV, MCH, MCHC values 1, 2
3. Screen for celiac disease with tissue transglutaminase antibodies 2
4. Initiate empiric oral iron therapy (ferrous sulfate 325 mg daily) and reassess in 2 weeks 2
5. Refer for gastroenterology evaluation if iron deficiency is confirmed 2