From the Guidelines
Leukopenia and neutropenia in an 18-year-old male are most commonly caused by viral infections, medication side effects, and certain hematologic disorders. The causes of low white blood cell (WBC) and neutrophil counts can be multifactorial, including:
- Viral infections like HIV, hepatitis, influenza, and Epstein-Barr virus, which can temporarily suppress bone marrow function, leading to decreased WBC production 1
- Medications that commonly cause these conditions, such as chemotherapy drugs, certain antibiotics (e.g., trimethoprim-sulfamethoxazole), antipsychotics (like clozapine), and some anticonvulsants
- Autoimmune disorders, such as lupus or rheumatoid arthritis, which can cause neutropenia through immune-mediated destruction of neutrophils
- Hematologic disorders like aplastic anemia, myelodysplastic syndromes, or leukemia, which should be considered in young adults, although they are less common
- Nutritional deficiencies, particularly vitamin B12 or folate deficiency, which can impair WBC production
- Congenital causes like cyclic neutropenia or Kostmann syndrome, which are rare but should be considered if other causes are ruled out
Evaluation should include a complete blood count with differential, peripheral blood smear, and potentially bone marrow examination if the condition persists or is severe. Treatment depends on identifying and addressing the underlying cause, with close monitoring for signs of infection during periods of neutropenia, as recommended by the Infectious Diseases Society of America 1. Prompt initiation of empirical antibiotic therapy is crucial in febrile neutropenic patients to prevent rapid progression of infection.
From the Research
Causes of Leukopenia and Neutropenia
The causes of leukopenia and neutropenia in an 18-year-old male can be attributed to various factors, including:
- Vitamin deficiency (vitamin B12, folic acid) 2
- Drugs (hydroxyurea, phenytoin, methotrexate) 2
- Bone marrow failure syndrome 2
- Aplastic anemia, a rare but serious hematological disease 2
- Chemotherapy-induced neutropenia, which can increase the risk of febrile neutropenia 3, 4
- Certain antibiotics, such as cefazolin and cefoxitin, which can cause leukopenia as a rare but well-described adverse drug reaction 5
- Other medical conditions, such as infections or autoimmune disorders, which can also contribute to leukopenia and neutropenia
Medication-Induced Leukopenia and Neutropenia
Medications can play a significant role in causing leukopenia and neutropenia, including:
- Beta-lactam antibiotics, such as cefepime, which have been associated with increased mortality in febrile neutropenia 6
- Cephalosporins, such as cefazolin, which can cause leukopenia as a cumulative dose-dependent phenomenon 5
- Chemotherapy agents, which can suppress bone marrow function and lead to neutropenia 4
Underlying Medical Conditions
Underlying medical conditions can also contribute to leukopenia and neutropenia, including:
- Pancytopenia, a condition characterized by a reduction in all three blood cell types (red blood cells, white blood cells, and platelets) 2
- Myelodysplastic syndrome, a group of disorders caused by poorly formed or dysfunctional blood cells 2
- Aplastic anemia, a rare but serious condition where the bone marrow fails to produce enough blood cells 2