Does any treatment retard or reverse deposition of CPP crystals causing the arthritis?
Unfortunately, there is no therapy to prevent deposition of CPP crystals or remove CPP deposits already present. Patients with an underlying disease such as primary hyperparathyroidism should have the disease treated. This may retard further CPP crystal deposition but will not resolve the crystals already deposited. Some patients have been treated with the following:
• Magnesium: may be useful in patients with low magnesium levels. Has also been described in patients with normal levels because in vitro studies showed that magnesium has inhibitory effects on CPP crystal nucleation and growth. Note that loop and thiazide diuretics, proton pump inhibitors, and calcineurin inhibitors can cause hypomagnesemia.
• Probenecid: it is postulated that probenecid lowers high PPi levels by blocking the ANKH anion channel. Though good theoretic rationale, this approach lacks evidence.
• Phosphocitrate: lowers PPi levels, but needs to be given intravenously because of poor oral absorption. Evidence from animal studies and in vitro human fibroblast analyses, but no safety or clinical efficacy data in humans.
• Polyphosphates: dissolve synthetic crystals and crystals from human menisci without cell damage; these agents have not been tested in vivo.
