Suffix that means abnormal reduction in number?

Here are some examples:

* Leukopenia: Abnormally low white blood cell count

* Thrombocytopenia: Abnormally low platelet count

* Neutropenia: Abnormally low neutrophil count

* Erythrocytopenia: Abnormally low red blood cell count

* Oligomenorrhea: Abnormally infrequent menstrual periods