Approximately 29 million people in the United States have crystal challenges. That’s 8.8% of the population, or 1 in every 11 people!* Some Interesting Facts Approximately 80% of crystals are mostly comprised of calcium compounds. Among men, the prevalence of crystals is 10.6% compared to 7.1% for women. 50% of those with crystals have a recurrence within 5 years of the initial event. Emergency department visits for crystal disease increased 20% between 2005 and 2009.* In the southeastern and central southern U.S., there is a high incidence of crystals. This region is often called the “Crystal Belt.”