article_snippet.sent: the numbers are the result of waste products in the blood forming crystals inside the kidneys, which eventually build up into a solid lump.
article_snippet.sent: the numbers can be excruciatingly painful - on a level, say experts, with childbirth.
article_snippet.sent: The pain often comes on suddenly and can cause the patient to 'writhe around in agony', the patient adds.
article_snippet.sent: The pain can be intense enough to cause nausea and vomiting.
article_snippet.sent: In that time, it may cause persistent or intermittent pain in the back, groin or side, a need to urinate more than usual, and pain when urinating.
article_snippet.sent: Signs of this include a fever, shivering, extreme weakness, diarrhoea, or cloudy and bad-smelling urine.