Why Do Kidney Stones Form?

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What Are Kidney Stones?

Kidney stones, which are also known as “nephroliths” or “renal calculi,” are pieces of solid materials in the kidney(s) that are formed from different compounds. Some of the laboratory tests used to detect and confirm the presence of kidney stones are ultrasonography, computed tomography scan, or an X-ray. Kidney stones vary in size (can be as small as the point of a pin) and in the severity of the pain. About seventy to eighty percent of kidney stones measure less than six millimeters, usually have minimal or no symptoms, and do not impede urine flow. Usually, stones can be addressed through conservative treatments that will eventually resolve the problem by spontaneously passing them out of the body through urination. On the other hand, kidney stones larger than two to three centimeters may obstruct urine flow and cause the most common presenting symptom, which is an enormous pain (renal colic) felt in the flank that may radiate to the abdomen and inguinal area. In males, the pain can extend to the testicles; and in females, to the labia.

The Kidney – Know Its Physiology

The functions of the kidneys are primarily the excretion of metabolic wastes and the regulation of the water-salt balance. Blood pumped out by the heart (called the “cardiac output”) is delivered to the kidneys, which are filtered out by nephrons (functional units of the kidneys). In fact, about one quarter of cardiac output goes to this filtering plant of the body daily. In the normal filtration process of a kidney, blood flows in and out of it. About one percent of the small molecules in the blood composition is filtered. White blood cells and proteins have large molecules and, hence, do not pass through the filter but are reabsorbed back into the system. These filtered blood compositions become urine that flows through the ureters, then to the urinary bladder, through the urethra, and then is finally excreted from the body.

Kidney Stone Formation

“Nephrolithiasis” is the process of forming kidney stones. Filtered substances make the urine in the kidneys more concentrated. High levels of calcium, oxalate, and phosphorous in the concentrated urine when combined with other compounds will form crystallized substances in the kidneys, which, hence, are the formation of renal stones. Dehydration puts a huge thrust in the formation of kidney stones due to high urine concentration and scanty urine output.

Four Main Types of Kidney Stones Classified According to Specific Crystal Contained

• Calcium stones (oxalate and phosphate)
• Cystine stones
• Uric acid stones
• Struvite stones
What Predisposes Someone to Kidney Stone Formation?

Anyone can get renal stones, but the following predisposing factors are strongly linked to the condition.

• Men are more affected than women.
• Inadequate fluid intake. People who drink less water are at higher risk of developing kidney stones due to high urine concentration. This factor facilitates excessive water conservation in the kidney.
• High sodium diet.
• Overweight and obese people.
• Anatomical blockage of the urinary tract (congenital deformity).
• Family history of kidney stones.
• Endocrine condition such as hyperparathyroidism, which is oversecretion of hormones of the parathyroid glands causing more calcium in the blood than the body needed.
• Frequent or recurrent urinary tract infections.
• Gout, high concentration of uric acid in the blood.
• Inflammation of the bowel or history of gastrointestinal surgery.
• Taking certain medications such as calcium-based antacids, phosphate-binding antacids, and diuretics.

Regardless of the factors listed above, keep in mind that kidney stone formation can be prevented by diet and lifestyle modification. Avoidance of stone-forming foods is helpful. Most importantly, drinking about two to three liters of fluids (water) in a day is the best way to prevent formation of kidney stones.


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