fluctuating neutrophil count

Question

In the last couple of months, my absolute neutrophil count started to strongly fluctuate in a range from 750 to 1500. What can be the explanation for this? (I am in stage B3, CD4 approx.150). Are their other causes, besides bone marrow suppression by medication, that can lower the neutrophil count? Does an infection increase (as a reaction) or just decrease (by depletion) the neutrophil count? What risks are associated with a low neutrophil count?

Answer

The most common cause of a low neutrophil count (neutropenia or leukopenia) is medication effects. The drugs that most commonly cause neutropenia include ganciclovir, trimethoprim-sulfamethoxazole (Bactrim or Septra, usually when used at high doses to treat PCP), and AZT, but that's just the short list.

Other causes include disseminated infection with organisms that can invade and replace the bone marrow. These would typically include mycobacterial infections, such as tuberculosis or disseminated M. avium complex (MAC), or fungal infections, especially histoplasmosis. Lymphoma can also cause neutropenia through bone marrow replacement. Such cases tend to occur in people with advanced HIV disease (CD4 less than 50), and are usually accompanied by "pancytopenia" (low red blood cell and platelet count as well as neutropenia).

Finally, HIV infection itself can lead to leukopenia, probably through changes in the activity and quantity of cytokines.

In HIV-infected patients neutropenia does not appear to be quite as dangerous as it is in patients on cancer chemotherapy. Nevertheless, when the absolute neutrophil count (ANC) falls below 500 there may be a higher risk of some bacterial and fungal infections. (To calculate the ANC you just multiply the total white blood cell count by the percentage of neutrophils). If you can't treat the cause (for example, by changing or dose-reducing the offending medication), then G-CSF (Neupogen) can be helpful. It has to be injected and it's quite expensive, but it usually works to bring the neutrophil count up.