Overview of kidney stone
Kidney stones occur in a disorder known as urolithiasis, which is characterized by the formation of one or more calcified crystals in the kidneys. These crystals are commonly referred as stones and are associated with pain in the abdominal and groin region.
Kidney stones are observed in about 5–15% of the population worldwide and their occurrence is 2–3 times more common in men than women. Adults are frequently affected when compared to other ages. Ethnically, it is more common in white individuals than Asian individuals and geographically it is more common in hot and arid regions.1,2
Signs and Symptoms of kidney stone
Individuals with kidney stones may be asymptomatic or may suffer from various features based on the severity of the condition. Asymptomatic individuals may only notice occasional stones in their urine. In other individuals, the symptoms observed may be general or specific to the kidney or urinary system.
Symptoms that are specific to the urinary system include
- Hematuria (blood in the urine)
- Absence or urine (dysuria) and other symptoms
The specific area of pain may at times point at the location of the stone. Stones in the kidney give rise to vague pain in the kidney borders and are associated with hematuria while a feeling of cramps, with pain in the abdominal region and dysuria or urinary frequency point towards the stones being lodged in the ureters. The pain in case of kidney stones may radiate up to the genital organs and the groin region.
The general symptoms that may be noted along with the specific features include restlessness, feeling of vomiting (nausea), vomiting, fever and chills.1,2
Causes of kidney stone
Kidney stones may form due to a variety of factors that alter the concentration of urine resulting in crystallization of the substances that are normally excreted.
The kidney stones have been classified into about five types based on their composition and are associated with various disorders accordingly.
In majority of the cases (about 60–80%) the kidney stones contain calcium oxalate, phosphate or both and result from certain underlying disorders such as hypercalciuria (increased amount of calcium in the urine) or may occur without any obvious cause.
Bacterial infection results in the formation of stones in about 10–15% of the individuals and the stones are composed of struvite.
Hyperuricemia and hyperuricosuria
Certain disorders such as hyperuricemia and hyperuricosuria wherein the kidney stones are composed of uric acid contribute to another 5–10% of the cases.1,2
Some of the factors that have been associated with an increased incidence of kidney stones include:
- Family history of kidney stones
- Insulin resistance
- History of disorders such as hypertension, primary hyperparathyroidism, gout
- Long standing acidosis
- Structural abnormality of the urinary tract
- Consumption of drugs such as triamterene, indinavir and acetazolamide
These factors may influence the urine volume, its concentration and the ratio of stone inhibiting factors (certain proteins) to the stone forming factors thereby resulting in the formation of stones in the kidney.3,4
Diagnosis of kidney stone
The diagnostic process involves a detailed analysis to identify the number, position and composition of the kidney stones and also to confirm the underlying disorder that would have resulted in the formation of the stones.
The diagnosis begins with recording a detailed personal, medication and family history to identify the clues that would point out the underlying disorder and probably identify the causes. Physical examination is performed to confirm the signs and symptoms noted.
Further investigations that are advised include the following:
Urine analysis is performed in all affected individuals to study the urine pH, evaluate hematuria, perform culture to check for bacteria, check for the presence of stones and other associated features.
Abdominal ultrasonography is advised especially in females and in some males to identify the presence of stones and rule out other abnormalities.
Plain X-ray of the lower abdomen
Plain X-ray of the lower abdomen used for initial evaluation of individuals in whom kidney stones are suspected.
Intravenous pyelography is usually advised in cases of stones within the urinary tract.
CT scan is highly useful in identifying all types of kidney stones in all locations in the urinary system.
Blood tests are done to identify the levels of various constituents and hormones that may point towards the cause and also help identify any underlying or associated disorders.1–3
Treatment for kidney stone
The treatment modality followed is based on factors such as
- The severity of condition
- Number of kidney stone
- Underlying conditions associated with it
In case of emergency situations, the affected individual is required to be hospitalized to prevent any further danger to life. In asymptomatic cases with small stones that are less than two in number are managed conservatively while larger stones may require surgical removal. In many individuals, the stones those are lesser than 4 mm in size tend to pass out after about two weeks of conservative management.
The conservative approach involves dietary recommendations and administration of medications.
Dietary recommendations advised are:
- Adequate intake of dietary calcium
- Reduced intake of animal proteins and salt
- Increased consumption of fruits and vegetables
- Increased fluid intake (at least >2 L/day)
The medications advised include the following:
Thiazide diuretics, allopurinol, potassium citrate: To prevent the formation of stones.
Antibiotics and painkillers: To counter any infection and pain associated with the stones.
Other appropriate medications
The surgical treatment options include:
These surgical procedures are minimally invasive procedures, which may or may not require hospitalization for a day or two.2–6
Prevention of kidney stone
Following the dietary recommendations as mentioned before can prevent the formation of kidney stones and its recurrence. Also, appropriate medical or surgical therapy should also be completed. Periodic visit to the doctor may be necessary to monitor the condition.1
Complications for kidney stone
The complications of kidney stones include:
- Kidney failure
- Stricture of the ureter
- Septic infection of the kidney and associated structures
- Urine extravasation2
Early diagnosis and appropriate management is helpful in preventing complications that may be life-threatening at times.
1.Parmar MS. Kidney stones. BMJ. 2004; 328; 1420–1424.
2.Portis AJ, Sundaram CP. Diagnosis and initial management of kidney stones. Am Fam Physician. 2001; 63:1329–1238.
3.Heilberg IP, Schor N. Renal stone disease: Causes, evaluation and medical treatment. Arq Bras Endocrinol Metab. 2006; 50(4): 823—831.
4.Moe OW. Kidney stones: Pathophysiology and medical management. Lancet. 2006; 367: 333–344.
5.Miller NL, Lingeman JE. Management of kidney stones. BMJ. 2007; 334: 468—472.
6.Coe FL, Evan A, Worcester E. Kidney stone disease. J Clin Invest. 2005; 115: 2598–2608.