The most important and often life-saving treatment is the preventive therapy of granulocyte colony-stimulating factor (G-CSF), in the form of filgrastim, which regulates the production of neutrophils within the bone marrow, but shortens the neutropenic cycle to about 7-14 days and the duration of the severe condition. The subcutaneous injections, with median dosage of 1.5 μg/kg/day, can be given daily, intermittently once every three days, or timed to just treat the neutropenic period. The therapy is considered to be "safe and effective", with no significant adverse effects, besides a possibility of development of osteopenia.The granulocyte-macrophage colony-stimulating factor (GM-CSF) is less effective with more adverse effects. Another alternative is hematopoietic stem cell transplantation (HSCT), but is usually practiced in SCN, and in one case between two sibling donors, one of which was undergoing HSCT treatment for acute myeloid leukemia (AML) while the second had CyN and whose marrow was transferred, was also transferred CyN through allogeneic marrow grafting. It shows that CyN is a stem cell disorder. Yearly bone marrow examinations are not recommended. Prognosis
There is a very high risk of life-threatening infections and death at an early age. The quality of life and survival greatly improves with G-CSF treatment, which is practiced since the late 1980s. Unlike severe congenital neutropenia, individuals with cyclic neutropenia have a better response to G-CSF and do not have a risk of developing myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML).
Michael Mackey "postulates that the production of neutrophils is governed by long‐range stimulatory factors in a long feedback loop that has a built‐in time delay in the maturation of promyelocytes to fully differentiated neutrophils". It is also not clear what causes that the levels of secretory leucocyte protease inhibitor (SLPI), which influences the induction of the unfolded protein response (UPR), are not diminished and as such activation of UPR is absent in CyN compared to SCN, in other words, different ELANE mutations "have different effects on UPR activation, and SLPI regulates the extent of ELANE‐triggered UPR". A 2020 study published in Annals of the New York Academy of Sciences about the pathomechanism of CyN revealed that "some HSPCs escape the UPR‐induced endoplasmic reticulum (ER) stress and proliferate in response to granulocyte colony‐stimulating factor (G‐CSF) to a certain threshold at which UPR again affects the majority of HSPCs. There is a cyclic balance between ER stress-induced apoptosis of HSPCs and compensatory G‐CSF–stimulated HSPC proliferation followed by granulocytic differentiation"; in other words, CyN is "characterized by cycling UPR activities and cycling UPR‐escaping cells". Also, the most probable reason that from the same mutation variant develops SCN and not CyN is due to more severe damage caused by UPR stress in SCN. Diagnosis
A diagnosis is usually confirmed by monitoring absolute neutrophil (ANC) count three times per week for at least six weeks. The confirmation can be assisted with Lomb periodogram.