Gene Simmons is battling kidney stones, which may explain why Kiss were forced to end their most recent tour leg a little early last month.

According to TMZ, the bassist was admitted to Cedars-Sinai Hospital this morning and had a stent inserted during a noninvasive, hour-long procedure.

Kidney stones are small pebbles of salt and minerals that can build up when a person doesn't have enough liquid in their system. They make urinating very painful. The stent is designed to help Simmons expel the stones more easily on his own. The report notes that the device will be removed, along with any remaining stones, in about a week.

On Sept. 13, Simmons tweeted that the band was postponing the last three dates of the most recent leg of its farewell End of the Road tour so that he could "do a medical procedure." He assured fans the issue was "nothing serious," but it needed to be attended to promptly.

After overcoming an earlier battle with the condition in 2009, Simmons put his kidney stones up for auction on eBay and raised $15,000 for charity.

The band will embark on the ninth-annual Kiss Kruise on Oct. 30. The five-day voyage will depart from Miami with a lineup of guests that includes former Kiss guitarist Bruce Kulick, the Darkness, Warrant and former Guns N' Roses drummer Steven Adler.

Kiss are currently scheduled to resume the End of the Road tour in Australia with a show in Perth on Nov. 16. Makeup dates for the three postponed U.S. dates haven't been announced yet.


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