FIELD: biotechnology.SUBSTANCE: method for inhibiting bone resorption in a subject, comprising administering to a subject a polypeptide that specifically binds the receptor activator of nuclear factor kappa B ligand (RANK-L) and which comprises two or more single immunoglobulin variable domains that specifically bind RANK-L and which essentially consist of 4 framework regions (FR1-FR4, respectively) and 3 hypervariable regions (CDR1-CDR3, respectively), wherein CDR1 is selected from SEQ ID NO: 1, CDR2 is selected from SEQ ID NO: 2, and CDR3 is selected from SEQ ID NO: 3, wherein the amount of the administered polypeptide is effective to alter one or more bone metabolism markers and/or bone homeostasis selected from the cross-linking telopeptide of type I collagen (CTX-1) and the N-terminal telopeptide of type I collagen (NTX-1) for at least 30 days after administration. Also described is a method of inhibiting osteoclast activity in a subject, comprising administering to a subject a polypeptide that specifically binds a receptor activator of nuclear factor kappa B ligand (RANK-L) and which contains two or more single immunoglobulin variable domains, which specifically bind RANK-L and which substantially consist of 4 framework regions (FR1-FR4, respectively) and 3 hypervariable regions (CDR1-CDR3, respectively) in which CDR1 is selected from SEQ ID NO: 1, CDR2 is selected from SEQ ID NO: 2, and CDR3 is selected from SEQ ID NO: 3, wherein the amount of the administered polypeptide is effective to alter one or more markers of bone metabolism and/or bone homeostasis selected from the cross-linking telopeptide of type I collagen (CTX-1) and the N-terminal telopeptide of type I collagen (NTX-1), at least 30 days after administration.EFFECT: methods described allow the subject to be administered polypeptides against RANK-L less frequently and/or at a lower dose, while maintaining effective inhibition of bone resorption and/or osteoclast activity in the subject for unexpect
