A 16-year-old male is brought to the emergency room for a broken arm incurred during a fall from gymnastics equipment. The patient appeared in good health, but a routine CBC during the ER visit revealed a white blood count (WBC) below the reference range and a very low neutrophil count. All other CBC results were within range. Patient results are as follows:
| CBC | Patient Result | Reference Range |
| Hemoglobin | 14.9 | 12-16 g/dL |
| Hematocrit | 44 | 37-47 % |
| RBC | 5.1 | 4.7-6.1 x 106/μL |
| MCV fL | 92 | 80-100 fL |
| MCH pg | 29 | 27-31 pg |
| WBC | 3.2 | 4.8-10.8 x 103/μL
|
| Differential | Patient Result | Reference Range |
| Neutrophils | 37% | 50-70% |
| Lymphocytes | 53% | 20-44% |
| Monocyte | 8% | 2-9% |
| Eosinophils | 2% | 0-4% |
| Basophils | 0.% | 0-2% |
| Absolute Counts | Patient Result | Reference Range |
| Neutrophils | 1.1 x 103/μL | 1.5-6.5 x 103/μL |
| Lymphocytes | 1.6 x 103/μL | 1.2-3.4 x 103/μL |
| Monocyte | 0.25 x 103/μL | 0.11-0.59 x 103/μL |
| Eosinophils | 0.09 x 103/μL | 0-0.5 x 103/μL |
| Basophils | 0.03 x 103/μL | 0-0.2 x 103/μL |
