Doctors in China have removed 420 kidney stones from a single patient, it's reported.
The man, named Mr He, underwent a two-hour operation to remove the stones at a hospital in Dongyang, eastern Zhejiang Province, the Qianjiang Evening Post reports.
Doctors at the hospital say it's likely that his tofu-heavy diet, and a lack of water, are to blame. "Soy products, especially gypsum tofu, are very high in calcium, the excess of which cannot be excreted from the body without a sufficient intake of water," says Dr Wei Yubin.
Mr He visited the doctor in May complaining of abdominal pain, and a subsequent CT scan revealed his left kidney was packed full of stones. The doctor says if Mr He had waited any longer then his kidney would have had to be removed.
Doctors operated on Friday in an agonising procedure that lasted about two hours.
Mr He said he had a history of suffering from kidney stones. Twenty years ago he had 10 stones removed using a procedure called lithotripsy, which sends shock waves to break up stones in the kidney, bladder, or ureter until they are small enough to pass in the urine.
"I have worked as a doctor for 30 years and have never seen so many stones," said Zhou Changchun, the attending surgeon, according to state newspaper Qianjiang Evening Post.
This time, the doctors used forceps to remove each stone one by one.
"We spent 45 minutes just taking out the tiny stones," said Dr Wei. "After the operation, my hands and legs were both numb."
Following the operation, Mr He took his stones home with him in a plastic bag.
While having 420 kidney stones sounds uncomfortable, it's a long way off the world record. In 2009, a doctor in India removed 172,155 stones from a patient's left kidney during a three-hour surgery, according to Guiness World Records.
The medical name for kidney stones is nephrolithiasis. If the stones cause severe pain, this is known as renal colic. Most kidney stones are small enough, between 4 to 5mm in diameter, to be passed naturally.
Kidney stones are quite common and usually affect people aged 30 to 60 years. It is estimated that renal colic affects about 10 to 20 per cent of men and three to five per cent of women, according to the NHS.