Leukopenia

Leukopenia(fromGreekλευκός(leukos)'white' andπενία(penia)'deficiency') is a decrease in the number ofleukocytes(WBC). Found in the blood, they are thewhite blood cells, and are the body's primary defense against aninfection. Thus the condition of leukopenia places individuals at increased risk of infection.
Symptoms may include:
Neutropenia, a subtype of leukopenia, refers to a decrease in the number of circulatingneutrophil granulocytes, the most abundant white blood cells. The termsleukopeniaandneutropeniamay occasionally be used interchangeably, as the neutrophil count is the most important indicator of infection risk.Agranulocytosisis an acute form of neutropenia.
Low white cell count may be due to acute viral infections, such as a cold orinfluenza. It has been associated withchemotherapy,radiation therapy,myelofibrosis,aplastic anemia(failure of white cell, red cell and platelet production), stem cell transplant, bone marrow transplant,HIV,AIDS, and steroid use.
Other causes of low white blood cell count includesystemic lupus erythematosus,Hodgkin's lymphoma, some types ofcancer,typhoid,malaria,tuberculosis,dengue,rickettsial infections, enlargement of thespleen,folatedeficiencies,psittacosis,sepsis,Sjögren syndromeandLyme disease. It has also been shown to be caused by deficiency in certainminerals, such ascopperandzinc.
Pseudoleukopenia can develop upon the onset of infection. The leukocytes (primarily neutrophils, responding to injury first) start migrating toward the site of infection, where they can be scanned. Their migration causes bone marrow to produce more WBCs to combat infection as well as to restore the leukocytes in circulation, but as the blood sample is taken upon the onset of infection, it contains low amount of WBCs, which is why it is termed "pseudoleukopenia".
Certain medications can alter the number and function of white blood cells.
Medications that can cause leukopenia includeclozapine, anantipsychoticmedication with a rare adverse effect leading to the total absence of all granulocytes (neutrophils, basophils, eosinophils).Minocycline, a commonly prescribed antibiotic, is another drug known to cause leukopenia. There are also reports of leukopenia caused by divalproex sodium orvalproic acid(Depakote), a drug used for epilepsy (seizures), mania (with bipolar disorder) and migraine.
Theanticonvulsantdrug,lamotrigine, has been associated with a decrease in white blood cell count.
The FDA monograph formetronidazolestates that this medication can also cause leukopenia, and the prescriber information suggests a complete blood count, including differential cell count, before and after, in particular, high-dose therapy.
Immunosuppressivedrugs, such assirolimus,mycophenolate mofetil,tacrolimus,ciclosporin,leflunomideandTNF inhibitors, have leukopenia as a known complication.Interferonsused to treatmultiple sclerosis, such asinterferon beta-1aandinterferon beta-1b, can also cause leukopenia.
Chemotherapytargets cells that grow rapidly, such as tumors, but can also affect white blood cells, because they are characterized by bone marrow as rapid growing.A common side effect of cancer treatment isneutropenia, the lowering ofneutrophils(a specific type of white blood cell).
Decreased white blood cell count may be present in cases ofarsenic toxicity.
Leukopenia can be identified with acomplete blood count.
Below areblood reference rangesfor various types leucocytes/WBCs.The 2.5 percentile (right limits in intervals in image, showing 95%prediction intervals) is a common limit for definingleukocytosis.