A kidney stone is a solid mass made up of tiny crystals. One or more stones can be in the kidney or ureter at the same time. Kidney stones are common. Some types run in families. They often occur in premature infants.
There are four main types of kidney stones: Calcium Stones; Struvite Stones – contain magnesium and ammonia; often horn-shaped and quite large; Uric Acid Stones – usually smooth, brown and softer than other forms of kidney stones; and Cystine Stones – often yellow and resemble crystals rather than stones.
Kidney stones come in a variety of shapes, sizes and colours. Some resemble grains of sand, while in rare cases others can grow to the size of a golf ball. If you have a kidney stone that is very small, it is unlikely to cause many symptoms. It may even go undetected and pass out painlessly when you urinate.
Symptoms usually occur if the kidney stone gets stuck in your kidney, starts to travel down the ureter (the tube that attaches each kidney to the bladder) – the ureter is narrow, and the kidney stone causes pain as it tries to pass through or causes an infection.
In these cases, common symptoms of kidney stones include:
persistent ache in the lower back, which is sometimes also felt in the groin – men may have pain in the testicles and scrotum
periods of intense pain in the back or side of your abdomen, or occasionally in your groin, which may last for minutes or hours
feeling restless and unable to lie still
nausea (feeling sick)
needing to urinate more often than normal
pain when you urinate
blood in your urine – this may be caused by the stone scratching the kidney or ureter
The biggest risk factor for kidney stones is not drinking enough fluids. Kidney stones are more likely to occur if you make less than 1 litre of urine a day.
To help avoid getting kidney stones, make sure you drink plenty of water each day so that you don't become dehydrated. It is very important to keep your urine diluted to prevent waste products forming into kidney stones.