Agents for preventing and treating thrombocytopenia

A method for increasing blood platelet formation in a patient in need of said therapy, comprising

• administering to said patient an effective amount for said therapy of, as active ingredient, a parathyroid hormone (PTH) or at least one PTH derivative effective for said therapy,
• wherein said PTH or PTH derivative is selected from groups (a) to (c):
• (1) a PTH derivative which comprises PTH(1-34), the constituent amino acid(s) of which may be substituted in the 8-position, 16-position and/or 34-position,
• (2) a PTH derivative which is such that one or more of the constituent amino acids of PTH(1-34), the constituent amino acid residue(s) of which may be substituted in the 8-position, 16-position and/or 34-position, are deleted, and
• (3) PTH or a PTH derivative selected from the group consisting of human PTH(1-34), human PTH(1-34)-NH2, human PTH(1-37), human PTH(1-64), human PTH(1-84), human PTH(35-84) and bovine PTH(1-34).