The invention provides kits and methods for evaluating the myelosuppressive state of a patient. These methods and kits provide a useful adjunct for cytotoxic and myelosuppressive therapies. By establishing threshold levels of certain cytokines as a surrogate for myelosuppression, treatment protocols can be optimized to reduce myelotoxicity, while maximizing effective dose. Measured levels of one or more cytokines in a patient subjected to cytotoxic therapy, relative to a normal population, may be used to determine the dose of a hematopoietic cytokine to be administered to the patient.