KIDNEY STONES

Definition: Kidney stones are calculi that develop anywhere in the urinary tract or kidneys. They are a common cause of pain, obstruction and secondary infections of the urinary tract. They vary in size from as small as a grain of sand to as large as a golf ball. Kidney stones typically leave the body in the urine stream. If they grow relatively large before passing, they may cause obstruction of a ureter and the resulting distension with urine can cause severe pain which is most commonly felt in the flank, lower abdomen and groin.

Types of stones include:
Calcium type I
: composed mainly of calcium salts; linked to increased small bowel absorption of calcium unrelated to intake.

Calcium type II
: composed mainly of calcium salts; linked to increased dietary calcium intake.

Calcium type III
: composed mainly of calcium salts; linked to increased vitamin D synthesis (secondary to renal phosphate loss).

Calcium oxalate
: composed mainly of calcium oxalate salts; linked to primary intestinal disorders and/or
chronic diarrhoea in inflammatory bowel disease.

Struvite
: composed mainly of magnesium ammonium phosphate stones; found mainly in women;
usually occur secondary to infection with urease-producing organisms (Proteus, Pseudomonas, Providencia and Klebsiella)

Uric acid
:composed of uric acid these stones are linked to metabolic defects or dietary excess of uric acid.

Cystine
: made up of cystine crystals, these usually occur secondary to chronic diarrhoea,  renal tubular acidosis and/or chronic hydrochlorothiazide treatment.

Aetiology / Major causative factors and risk factors that can contribute to the incidence of kidney stones include the following:
: High phosphorus diet
: Bone loss
: Soft drinks
: Elevated urinary calcium excretion
: High meat consumption
: Excess intake of calcium, oxalate, or purines in predisposed individuals
: Inadequate fluid intake
: Sedentary occupation
: Area of high humidity, elevated temperatures
: Hyperparathyroidism
: Renal tubule defects (e.g., renal tubule acidosis)
: Inflammatory bowel diseases
: Genetics
: Gout
: Use of certain diuretic medications