KCitr is an alkaline compound which may be used in metabolic acidosis. Potassium is an alkaline metal that plays a pivotal role in the function of all living cells. Citric acid is a key molecule of the Krebs cycle, and it is abundant in bone where exhibits a stabilizing function. Although clinical data regarding the KCitr effectiveness on calcium metabolism are encouraging, it is still unclear whether the beneficial effects are due exclusively to the buffering function or whether KCitr may affect the bone cells activity. The purpose of this study is to evaluate the effects of KCitr on bone metabolism. We hypothesize that administration of potassium citrate to postmenopausal women with osteopenia will delay (or will prevent) the weakening of bone mass.