Methods and kits useful for guiding osteoporosis related therapy

A method for guiding administration of a therapeutic agent in a subject afflicted with osteoporosis, comprising:

• a) obtaining a first biological sample from the subject;
• b) administering to said subject a parathyroid hormone (PTH) based therapeutic composition comprising PTH1-84 or PTH1-34;
• c) obtaining a second biological sample from said subject after administration of said therapeutic;
• and
• d) evaluating said first and second samples for a PTH antagonist level, and optionally a total PTH level or a PTH1-84 level, wherein the PTH antagonist is PTH7-84,
• wherein if the PTH antagonist is present at a higher level in the second sample versus the first sample, and/or if the ratio of the PTH antagonist versus the total PTH level or the PTH1-84 level is higher in the second sample versus the first sample, then the subject may be considered a candidate for treatment with said PTH based therapeutic composition, and
• wherein, if the PTH antagonist is present at the same or lower level in the second sample versus the first sample, and/or if the ratio of the PTH antagonist level versus total PTH level or the PTH1-84 level is the same or lower in the second sample versus the first sample, then the subject is not considered a candidate for treatment with said PTH based therapeutic composition.