On Thursday, a Congressional hearing will be focusing on drug company price hiking. The issue blew up at the end of last year when Martin Shkreli’s Turing Pharmaceuticals raised the price of anti-parasite drug Daraprim to $750 per pill. Still, big price hikes are turning out to be an industry-wide problem.

Take Prevastatin, a cholesterol drug that’s been around for years. It was pretty cheap in 2013. But Lisa Gill of Consumer Reports said between that year and the next, it saw a 573 percent price increase.

“That drug is no longer available on these four dollar, ten dollar cheap lists,” she said.

It’s not the only drug to rocket in price. Technology company DRX surveyed pharmaceutical firms recently. It found prices had doubled for scores of drugs.

Walid Gellad is associate professor of medicine at the University of Pittsburgh. He said companies raise prices because they can, and good luck to consumers trying to understand how any of this works. First, there are list prices, which are published.

“And then there are certain rebates that are negotiated that are invisible to everyone,” he said. “So in the end you don’t know exactly what the price is so it’s hard really to fathom exactly what’s going on.”

Gellad said some states are interested in bringing in transparency laws around drug pricing.