The invention relates to a method for determining, diagnosis, prognosis, treatment guidance, treatment monitoring, risk assessment and/or risk stratification of patients with abnormal platelet levels comprising providing a sample of said patient, determining a level of proadrenomedullin (proADM) or fragment(s) thereof in said sample, wherein said level of proADM or fragment(s) thereof correlates with the abnormal platelet levels in said patient. In embodiments of the invention, a level of proADM or fragment(s) thereof of high severity indicates low platelet levels in the subject and subsequent initiating or modifying a treatment of the patient to improve said condition. In some embodiments of the invention the method comprises determining a level of one or more additional markers in a sample isolated from the patient, such as the level of platelets, the level of PCT or fragment(s) thereof, one or more markers of thrombocytopenia and/or one or more markers of an inflammatory response.