Diseases that affect the kidney – kidney stones


Having discussed the anatomical structure of the urinary tract and the functions of the kidney in last week Thursday’s edition of the Guardian Newspaper, I would like to continue this week with diseases of the kidney. To begin with, I shall be considering kidney stones.

A kidney stone is a crystalline piece of material that is formed from the minerals that have to be filtered through the kidney in the process of urine formation. Also known as renal calculus, the kidney stone has a direct link to the kidney and its function. It is fallout of the filtering function of the kidney. Here again as in the case of the liver, everything should be done to prevent this condition, save the kidneys from damage and probable death of an individual. Kidney stones come in various sizes and some of the very small ones can be passed out with the urine without being noticed. However, stones whose diameter may be equal to or larger than the lumen of the ureter could obstruct the ureter and give rise to very severe pain known as renal colic.

Classification of kidney stones: Kidney stones can be classified according to their mineral composition and where they may be located in the urinary system.

Calcium oxalate stones are by far the most common type of stones in human beings. As the name suggests, it is formed by calcium and oxalate. Calcium oxalate stones are formed when the pH of the urine is acid, low pH. Calcium phosphate stone is formed when the pH is predominantly alkaline.

Struvite stones depend on the presence of infection of the kidneys. Diet does not play any significant role in the formation of these stones. It also means that in the absence of infection there cannot be struvite stones. Uric acid stones are formed when one eats diets that are rich in animal proteins such as red meat, organ meats and fish. An acid pH needs to be present for the formation of . Cystine and xanthine stones complete the classification of stones to be found among humans.

In considering the classification by location, we see such stones as nephrolithiasis referring to stones in the kidney, ureterolithiasis for those in the ureter and cystolithiasis for the bladder.

Signs and symptoms: Renal colic is the most typical symptom of kidney stones, especially those that are big enough to obstruct the ureter. It is an intermittent kind of pain that comes in waves, which last for 30 to 60 minutes. These are peristaltic waves generated by the ureter as it attempts to dislodge the stone causing an obstruction in it. The pain may start from the lower back or the side of the body and radiates to the pelvic region or the inner aspect of the thigh. Other symptoms of kidney stones are nausea and vomiting, sweating, restlessness, passage of blood in the urine and urinary urgency (inability to hold urine). Pain while urinating, fever and pus in the urine have been reported in cases of kidney stones.

Risk factors associated with kidney stones: There are certain risk factors that increase the likelihood of an individual having kidney stones.

Dehydration could be considered the first and most important risk factor to having kidney stones. The most frequently encountered reason why an individual is dehydrated is lack of sufficient intake of water. In this state of dehydration, the blood becomes more viscous as the minerals and all the wastes in it accumulate. The circulation slows down and this state of affairs causes filtration of wastes and minerals from the tubules to the blood vessels to also slow down, allowing the minerals to react and adhere to each other, forming stones.

An acid environment, which is also a consequence of dehydration, is another risk factor.

Obese individuals have a higher risk of having kidney stones than those with normal weight. This is because such persons are usually full of acids in the presence of a slow and sluggish circulation. Other risk factors include high consumption of animal proteins, refined sugars, sodium, grape and apple juices.

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