Efficacy of Potassium Citrate in the Treatment of Postmenopausal Osteopenia

The purpose of this study is to investigate whether the use of alkali compounds, i.e. potassium citrate (K3C6H5O7, hereinafter KCitr) is effective in preventing the progression of osteopenia.

A randomized clinical trial (RCT, placebo-controlled, double-blind) has been planned to evaluate the effect of the daily administration of KCitr (3 g/die, K 30 mEq).

The efficacy will be evaluated by comparing the circulating levels of bone turnover markers at the baseline and after the treatment (3, 6 months).

Bone tissue carries out some of the important metabolic functions, including the regulation of acid-base balance. In order to buffer the systemic acidosis, the skeleton acts as a "ion exchange column" modifying the composition of the mineral portion, i.e. the hydroxyapatite. There is a linear correlation between elimination of calcium and acidosis: the higher is the acidosis, the higher will be the loss of calcium from bones. In vitro experiments showed that acidosis also directly influences the cellular component of bone by increasing the osteoclast activity and inhibiting the production of the mineralized matrix by osteoblast. Since the low pH is a risk factor that accelerates the bone loss, the use of alkalizing compounds could prevent the osteopenia or support the conventional therapy of the osteoporosis.

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.

Postmenopausal women with osteopenia (T score between -1.0 and -2.5) and no history of fracture will be randomized to assume KCitr ate or placebo, daily for six months. Primary outcomes will be evaluated by measuring markers of bone turnover, which will be measured at baseline (before treatment), in the mid-term (3 months) and at the end (6 months).

Eligibility Criteria:
Inclusion Criteria:

* Postmenopausal women, more than 5 years post menopause
* Osteopenia (T-score \< -1 and \> -2.5)
* Low risk of fracture (FRAX: \< 20 major osteoporotic; \< 3 hip fracture)

Exclusion Criteria:

* Hyperkalemia
* Renal insufficiency
* Nephrolithiasis
* Use of potassium sparing diuretics
* Use of potassium supplements
* Use of therapies influencing bone metabolism (e.g. corticosteroids, thiazide diuretics, aromatase inhibitors, estrogens)
* Use of protonic pump inhibitors
* Current or recent use of bisphosphonates (stopped less than three years prior to the start of the study)
* Gastrointestinal disorders that hamper nutrient absorption;
* Mental or psychiatric disorders that preclude the possibility of correctly adhering to the protocol