Kidney stone disease

Kidney stone disease (known as nephrolithiasis, renal calculus disease, or urolithiasis) is a crystallopathy and occurs when there are too many minerals in the urine and not enough liquid or hydration. This imbalance causes tiny pieces of crystal to aggregate and form hard masses, or calculi (stones) in the upper urinary tract. Because renal calculi typically form in the kidney, if small enough, they are able to leave the urinary tract via the urine stream. A small calculus may pass without causing symptoms. However, if a stone grows to more than 5 millimeters (0.2 inches), it can cause blockage of the ureter, resulting in extremely sharp and severe pain (renal colic) in the lower back that often radiates downward to the groin. A calculus may also result in blood in the urine, vomiting (due to severe pain), or painful urination. About half of all people who have had a kidney stone are likely to develop another within ten years.

Renal is Latin for "kidney", while "nephro" is the Greek equivalent. "Lithiasis" (Gr.) and "calculus" (Lat.- pl. calculi) both mean stone.

Most calculi form by a combination of genetics and environmental factors. Risk factors include high urine calcium levels, obesity, certain foods, some medications, calcium supplements, gout, hyperparathyroidism and not drinking enough fluids. Calculi form in the kidney when minerals in urine are at high concentration. The diagnosis is usually based on symptoms, urine testing, and medical imaging. Blood tests may also be useful. Calculi are typically classified by their location: nephrolithiasis (in the kidney), ureterolithiasis (in the ureter), cystolithiasis (in the bladder), or by what they are made of (calcium oxalate, uric acid, struvite, cystine).

In those who have had renal calculi, drinking fluids, especially water, is a way to prevent them. Drinking fluids such that more than two liters of urine are produced per day is recommended. If fluid intake alone is not effective to prevent renal calculi, the medications thiazide diuretic, citrate, or allopurinol may be suggested. Soft drinks containing phosphoric acid (typically colas) should be avoided. When a calculus causes no symptoms, no treatment is needed. For those with symptoms, pain control is usually the first measure, using medications such as nonsteroidal anti-inflammatory drugs or opioids. Larger calculi may be helped to pass with the medication tamsulosin or may require procedures such as extracorporeal shock wave lithotripsy, ureteroscopy, or percutaneous nephrolithotomy.

Renal calculi have affected humans throughout history with a description of surgery to remove them dating from as early as 600 BC in ancient India by Sushruta. Between 1% and 15% of people globally are affected by renal calculi at some point in their lives. In 2015, 22.1 million cases occurred, resulting in about 16,100 deaths. They have become more common in the Western world since the 1970s. Generally, more men are affected than women. The prevalence and incidence of the disease rises worldwide and continues to be challenging for patients, physicians, and healthcare systems alike. In this context, epidemiological studies are striving to elucidate the worldwide changes in the patterns and the burden of the disease and identify modifiable risk factors that contribute to the development of renal calculi.