Kidney stone disease

Kidney stone disease or urinary stone disease is a crystallopathy that occurs when there is an excess of minerals in the urine and not enough liquid or hydration. This imbalance causes tiny crystals 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 may pass out of the urinary tract through the urine stream. A small calculus may pass without causing any 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 to the groin. A calculus may also result in blood in the urine, vomiting (owing to severe pain), swelling of the kidney, 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 (Greek) and calculus (Latin; plural 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 concentrations. 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, being referred to medically as nephrolithiasis (in the kidney), ureterolithiasis (in the ureter), or cystolithiasis (in the bladder). Calculi are also classified by what they are made of, such as calcium oxalate, uric acid, struvite, or 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, medications such as thiazide diuretics, 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 for removal such as extracorporeal shockwave therapy (ESWT), laser lithotripsy (LL), or percutaneous nephrolithotomy (PCNL).

Renal calculi have affected humans throughout history, with descriptions 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, about 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, mainly between the ages of 40 and 60. The prevalence and incidence of the disease continue to rise worldwide.