The clinical presentation is highly variable. Most patients with renal stone disease are asymptomatic, whereas others present with pain, hematuria, urinary tract infection (UTI) or urinary tract obstruction. A common presentation is acute loin pain radiating to the anterior abdominal wall, together with hematuria, termed as renal colic. This is most commonly caused by ureteric obstruction by a calculus but the same symptom can occur in association with sloughed renal papilla, tumor or blood clot. The patient is suddenly aware of pain in the loin which radiates round the flank to the groin and often into the testes or labium in the sensory distribution of the first lumbar nerve. The pain steadily increases in intensity to reach the peak in a few minutes. The patient is restless and tries unsuccessfully to obtain relief by changing position or pacing the room. There is pallor, sweating and often vomiting. Frequency, dysuria and hematuria may occur. The intense pain usually subsides within 2 hours but may continue unabated for hours or days. It is usually constant during attacks, although slight fluctuation in severity may be seen. Intermittent dull pain in the loin or back may persist for several hours following the attack of renal colic. Other symptoms that may be present include fever with rigors and chills, urinary retention, abdominal bloating, loss of appetite and abnormally colored urine.

Patients with symptoms of renal colic should be investigated to determine the presence of the stone(s), to identify its location and to assess whether it is causing obstruction.

• Complete blood count: White blood count may be elevated in the presence of infection.
• 24-hour urine profile: The most common findings on 24-hour urine studies include hypercalciuria, hyperoxaluria, hyperuricosuria, hypocitraturia and low urinary volume.
• X-ray KUB: It is a very good initial investigation. The KUB film shows kidney, ureter and bladder. Over 90% of stones are radio-opaque so they are visible on plain X-ray. Calcium oxalate, struvite and phosphate stones are radio-opaque whereas uric acid stones are radiolucent.
• Ultrasonography: Majority of the stones can be diagnosed on ultrasonography.
• Intravenous urography: Renal function tests should be normal before performing intravenous urography. It provides the anatomical detail and functional status of the entire renal tract. If the renal function is disturbed, then intravenous urography should not be performed as contrast agent can further enhance renal injury. In such patients, renal function is assessed by measuring glomerular filtration rate via a 99Tc-DTPA renal scan.
• Non contrast enhanced helical CT KUB: This is currently the imaging modality of choice for renal tract stones. It accurately picks up almost all types of radiolucent and radio-opaque stones anywhere in the renal tract [10] [11].
• Retrograde pyelography: It can be performed safely in patients allergic to intravenous contrast media. It shows both radiolucent and radio-opaque stones, ureteral kinks and structures that may not be visualized easily on other studies.

Since most stones pass spontaneously through the urinary tract, the urine should be sieved for a few days after an episode of colic in order to collect the calculus for analysis.

The immediate treatment of renal colic is represented by the use of analgesia and antiemetics. Renal colic is often unbearably painful and demands powerful analgesia. Diclofenac 100mg given orally is often very effective. It can be followed by an intramuscular injection of 10-20mg morphine. There are various options for the treatment depending upon size, site and composition of the stones.

• Observation: 90% of stones which are less than 5mm usually pass spontaneously. Analgesia, antibiotics and plenty of fluid (3litres/day) is all that are needed.
• Medical expulsive therapy: 70% of stones which are 6-8mm in diameter can pass with medication. Tamsulosin 0.4mg given once at night, in addition to analgesics, is prescribed to ease the passage of the stone.
• Extracorporeal shock wave lithotripsy: This is a non-surgical modality for the treatment of stones. In extracorporeal shock wave lithotripsy, the stone is focused and bombarded with shock waves of sufficient energy to disintegrate the stone into fragments. These small fragments are then passed down the ureter into bladder and then to exterior through urethra.
• Percutaneous nephrolithotomy: The indications for this procedure include staghorn calculi, stones greater than 2.5cm in size, and failed extracorporeal shock wave lithotripsy. The stone is visualized and fragmented using ultrasonic, pneumatic or laser lithoclasts. 
• Retrograde intrarenal surgery: This is an endoscopic modality of renal stone removal. 
• Open surgery: The indications for open surgery include very large and complex stones occupying many calyces, morbidly obese patients and failure of previous procedures. Pyelithotomy is performed by placing the patient in lateral position via Morrison’s incision.

Most renal stones are small (less than 5 mm in diameter) and pass spontaneously in up to 80% of the people. A stone that has not passed within 1 to 2 months usually require intervention. The recurrence rate for urinary calculi is 50% within 5 years and 70% or higher within 10 years. The factors that predispose to recurrent stone formation include first attack before 25 years of age, single functioning kidney and abnormalities of the renal tract. Early recognition and immediate surgical drainage improves the prognosis.

Renal colic is caused by a blockage in the urinary tract which is mainly due to stones in the kidney. When these stones interfere with the flow of urine, they cause the kidneys to swell, producing waves of colicky pain. Kidney stones that can lead to renal colic can be made up of a variety of chemicals. Calcium oxalate stones occur due to hypercalciuria and hypercalcemia which mostly occurs in primary hyperparathyroidism [1] [2] [3]. Uric acid stones occur due to gout and myeloproliferative disorders. Struvite stones are formed by infection caused by urease producing bacteria e.g. Proteus and Staphylococci [4] [5]. Various enzyme disorders can lead to the formation of cysteine and xanthine stones [6] [7].

A number of factors increase the risk of developing renal stones. These include dehydration, hot climate, low fluid intake, high protein and salt intake, diet high in vitamin A, diuretic overuse, intestinal obstruction, family history of kidney stones, use of calcium based antacids, pregnancy, recent surgery and urinary tract infection. The congenital and inherited causes of kidney stones include familial hypercalciuria, hyperoxaluria, medullary sponge kidney, cystinuria and renal tubular acidosis type 1.

Renal stone disease is common, affecting individuals of all countries and ethnic groups. In the United States, the prevalence is about 1.2%, with a lifetime risk of developing a renal stone at age 60-70 of about 7% in men. In some regions, the risk is higher, most notably in countries like Saudi Arabia, where the lifetime risk of developing a renal stone in men aged 60 to 70 is over 20%. The risk of recurrence of stone formation within 1 year is 10% and within 10 years might be as high as 50%. Black people have a lower incidence of stone development compared to white people. The male to female ratio is 3:1; however, females have a higher incidence of infected hydronephrosis. Nephrolithiasis is rare in children. Approximately 5 to 10 children aged 10 months to 16 years develop kidney stones each year.

Urinary calculi consist of aggregates of crystals, usually containing calcium or phosphate in combination with small amounts of proteins and glycoproteins. Renal stones vary greatly in size. There might be sand-like particles anywhere in the urinary tract, or large round stones in the bladder. These stones are formed by the phenomenon of supersaturation of the urine by stone-forming constituents, including calcium, oxalate and uric acid [8] [9]. The resulting calculi may lead to muscle spasm, increased proximal peristalsis, local inflammation, irritation and edema at the site of obstruction. They can contribute to the development of pain through chemoreceptor activation and stretching of submucosal free nerve endings. The severity of pain depends on the degree and site of the obstruction, not on the size of stone. Staghorn calculi fill the whole renal pelvis and branch into the calyces. They are usually associated with infection and composed largely of struvite. Deposits of calcium may be present throughout the renal parenchyma, giving rise to fine calcification within it, especially in patients with renal tubular acidosis, hyperparathyroidism, vitamin D intoxication and healed renal tuberculosis. Cortical nephrocalcinosis may occur in areas of cortical necrosis, typically after acute renal injury in pregnancy or other severe acute kidney injury. Another factor that leads to stone development is the formation of Randall’s plaques. Calcium oxalate precipitates on the basement membrane of the thin loops of Henle, resulting in Randall’s plaque and eventually a calculus.

Renal colic can be prevented by making a few lifestyle modifications. These include:

• Excess fluid intake: The patient is encouraged to drink plenty of fluids to help decrease pain and flush blockages from the urinary tract. An intake of more than 2.5 liters of liquids per day is usually advised. 
• Dietary modifications: Eating foods like okra, oysters and raw broccoli that contain rich doses of magnesium can help strengthen the immune system and reduce the incidence of urinary tract infections that lead to stone formation. Foods rich in oxalate, vitamin C, cereal fiber, high salts and fats should be avoided. Sulfur containing protein (egg, meat, fish) should be restricted in cystinuria.
• Medications: Drugs (such as thiazide diuretics, allopurinol and calcium citrate) are given to reduce the risk of stone formation according to the type of the stone. Idiopathic hypercalciuria is treated with bendroflumethiazide.
• Frequent urination: This keeps the level of toxins down and prevents the formation of kidney stones.

Renal colic is a severe type of abdominal pain caused by kidney stones. It typically begins in the abdomen and radiates to the hypochondrium or the groin. The pain is often constant and colicky in character due to ureteral peristalsis. It may be associated with fever, rigors, chills, nausea, vomiting and blood in urine. The pain is usually located on one side, but might be on both sides of lower back. Nephrolithiasis is more common at 20 to 50 years of age. These stones consist of crystals, usually containing calcium or phosphate in combination with small amounts of proteins. Successful management includes removal of the stone and prevention of recurrence.

Renal colic is a type of pain caused by kidney stones. The pain begins in abdomen and radiates to the groin. It is most common in men between 20 to 30 years of age. The patients usually present with severe pain, fever, nausea, vomiting and blood in the urine. With proper treatment and preventive measures, the disease has a very good prognosis.

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