Kidney Stones

Renal calculi also called Kidney stones: 
Kidney stones may form anywhere in the urinary tract but usually develop
in the renal pelvis or calyces.  Such formation follows precipitation
of substances normally dissolved in the urine ( calcium oxalate, calcium
phosphate, magnesium ammonium phosphate, or, occasionally, urate or cystine
).  The causes are unknown, risk factors include: 

 * Dehydration – decreased urine production concentrates calculus
– forming substances. 

 * Infection – damage and infected tissue serves as a site for
calculus development; pH changes provide a favorable medium for calculus
formation (especially for magnesium ammonium phosphate or calcium phosphate
calculi ); or infected calculi (such as; magnesium ammonium phosphate or
staghorn calculi ) may develop if bacteria serve as the nucleus in calculus
formation.  Such infections may promote destruction of renal parenchyma
( functional elements of an organ ).

 * Obstruction – Urine stasis ( as in immobility from spinal cord
injury ) allows calculus constituents to collect and adhere, forming calculi. 
Obstruction also promotes infection, which in turn, compounds the obstruction.

 * Metabolic factors – Hyperparathyroidism, renal tubular acidosis,
elevated uric acid levels (usually with gout ), defective metabolism of
oxalate, genetically defective metabolism of cystine, and excessive intake
of vitamin D or dietary calcium may predispose to renal calculi.

Kidney stones or renal calculi vary in size and may be solitary or
multiple.  They may remain in the renal pelvis or enter the ureter
and may damage renal parenchyma.  Large calculi cause pressure necrosis,
and may cause obstruction depending on location.


Symptoms varies with size, location, and cause of the calculus.

Pain – the pain of classic renal colic travels from the costovertebral
angle to the flank, the supra pubic region, and the external genitalia. 
The pain fluctuates in intensity and may be excruciating at its peak. 
If the stone or calculi are in the renal pelvis and calyces, pain may
be more constant and dul
l.  Back pain occurs from calculi
that produce and obstruction within a kidney.  Nausea and vomiting
accompany severe pain.  Patient may have abdominal distention,
fever and chills, with possibly hematuria (blood in
urine), pyuria (pus in the urine), and rarely, anuria (suppression
of urine).


Because 90% of renal calculi are smaller than 5 mm in diameter, treatment
usually consists of measures to promote their natural passage.  Along
with increase, vigorous hydration, such treatment includes antimicrobial
for the infection, varying with the cultured organism. 
Your doctor may prescribed an analgesics for pain, and diuretics
to prevent urine stasis and further calculus formation.  Prophylaxis
to prevent calculus formation includes; a low calcium diet , and
daily intake of ascorbic acid to acidify the urine.

Stones (calculi) too large for natural passage may require surgical
removal. When calculus in in the ureter, a cystoscope may be inserted through
the urethra and the calculus manipulated with catheters or retrieval instruments. 
Extraction of calculi from other areas may necessitate a flank or lower
abdominal approach.  Percutaneous ultrasonic lithotripsy and extracorporeal
shock wave lithotripsy shatter the calculus into fragments for removal
by suction or natural passage.