Renal Stone

Overview

A kidney stone, also known as a renal calculus is a solid concretion or crystal aggregation formed in the kidneys from dietary minerals in the urine.

Urinary stones are typically classified by their location in the kidney, ureter, or bladder or by their chemical composition (calcium-containing, struvite, uric acid, or other compounds). About 80% of those with kidney stones are men. Men most commonly experience their first episode between 20-30 years of age, while for women the age at first presentation is somewhat later.

Kidney stones typically leave the body by passage in the urine stream, and many stones are formed and passed without causing symptoms. If stones grow to sufficient size (usually at least 3 millimeters (0.12 in) they can cause obstruction of the ureter. Ureteral obstruction causes postrenal azotemia and hydronephrosis (distension and dilation of the renal pelvis and calyces), as well as spasm of the ureter. This leads to pain, most commonly felt in the flank (the area between the ribs and hip), lower abdomen, and groin (a condition called renal colic). Renal colic can be associated with nausea, vomiting, fever, blood in the urine, pus in the urine, and painful urination. Renal colic typically comes in waves lasting 20 to 60 minutes, beginning in the flank or lower back and often radiating to the groin or genitals. The diagnosis of kidney stones is made on the basis of information obtained from the history, physical examination, urinalysis, and radiographic studies. Ultrasound examination and blood tests may also aid in the diagnosis.

Signs and symptoms

The hallmark of stones that obstruct the ureter or renal pelvis is excruciating, intermittent pain that radiates from the flank to the groin or to the genital area and inner thigh. This particular type of pain, known as renal colic, is often described as one of the strongest pain sensations known. Renal colic caused by kidney stones is commonly accompanied by urinary urgency, restlessness, hematuria, sweating, nausea, and vomiting. It typically comes in waves lasting 20 to 60 minutes caused by peristaltic contractions of the ureter as it attempts to expel the stone. The embryological link between the urinary tract, the genital system, and the gastrointestinal tract is the basis of the radiation of pain to the gonads, as well as the nausea and vomiting that are also common in urolithiasis. Postrenal azotemia and hydronephrosis can be observed following the obstruction of urine flow through one or both ureters.

Treatment

Treatment depends on the type of stone and the severity of your symptoms.

Kidney stones that are small usually pass on their own. When the stone passes, the urine should be strained so the stone can be saved and tested.

Drink at least 6 - 8 glasses of water per day to produce a large amount of urine. See also: Kidney stones - self-care

Pain can be severe enough to need narcotic pain relievers. Some people with severe pain from kidney stones need to stay in the hospital. You may need to get fluids through a vein (intravenous).

Depending on the type of stone, your doctor may prescribe medicine to decrease stone formation or help break down and remove the material that is causing the stone.

Medications can include:

• Allopurinol (for uric acid stones)
• Antibiotics (for struvite stones)
• Diuretics
• Phosphate solutions
• Sodium bicarbonate or sodium citrate
• Water pills (thiazide diuretics)

Surgery is usually needed if:

• The stone is too large to pass on its own
• The stone is growing
• The stone is blocking urine flow and causing an infection or kidney damage
• The pain cannot be controlled

Today, most treatments are much less invasive than in the past.

• Extracorporeal shock-wave lithotripsy is used to remove stones slightly smaller than a half an inch that are located near the kidney or ureter. It uses sound or shock waves to break up stones. Then, the stones leave the body in the urine.
• Percutaneous nephrolithotomy is used for large stones in or near the kidney, or when the kidneys or surrounding areas are incorrectly formed. The stone is removed with tube (endoscope) that is inserted into the kidney through a small surgical cut.
• Ureteroscopy may be used for stones in the lower urinary tract.
• Rarely, open surgery (nephrolithotomy) may be needed if other methods do not work or are not possible.