Absolute lymphocytopenia (lymphopenia) occurs when the absolute lymphocyte count is less than the lower limit of normal for age, gender and race. It may be secondary to one or more conditions.
Concerns:
(1) exclusion of relative lymphocytopenia (associated with neutrophilia or monocytosis)
(2) transient versus permanent
Infectious causes:
(1) HIV-1
(2) HTLV-1
(3) chikungunya
(4) malaria
(5) tuberculosis
(6) septic shock, bacteremia
(7) infectious mononucleosis (less often than atypical lymphocytosis)
(8) dengue fever
(9) Salmonella
(10) Camplyobacter
(11) influenza
(12) other viral infections
(13) leptospirosis
Therapy-related:
(1) corticosteroids
(2) chemotherapy
(3) radiation therapy
(4) epinephrine injection
(5) immunosuppressive therapy, especially antibodies against lymphocytes
(6) targeted therapy (rituximab, venurafenib)
Other:
(1) idiopathic CD4+ lymphocytopenia
(2) SLE or other autoimmune disorder
(3) Hodgkin's disease
(4) associated with lymphatic malformation
(5) congestive heart failure (possibly related to protein-losing enteropathy)
(6) adult respiratory distress syndrome (ARDS)
(7) severe protein-calorie malnutrition
(8) zinc deficiency
(9) splenomegaly
(10) extensive burns
(11) renal insufficiency
(12) Ethiopian ancestry
(13) primary immune deficiencies
(14) protein-losing enteropathy
(15) pulmonary silicosis
where:
• Some immune deficiencies may be associated with autoimmune manifestations.
• Protein losing enteropathy, GI lymphatic malformations and protein malnutrition may overlap.
• ARDS and renal insufficiency may caused by several of the other conditions listed.
