Urinary stone disease. By Dr.Aiman AL Solumany (R2) King Fahd General Hospital. In General. Urinary calculi are the third most common problem of the urinary tract, exceeded only by urinary tract Infections and pathologic conditions of the prostate. 1-Renal calculi
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By Dr.Aiman AL Solumany (R2)
King Fahd General Hospital
1- intrinsic factor.
2- extrinsic factors
history of kidney stones.
Peak - 20-40 years old
M : F - 3:1
F > M - stones 2nd to infections or abN
2-climate and seasonal factors :
.high protein and Na ca stones
.high purine pH hyperuricosuria
.low Vit B12 formation and excretion of oxalate.
The risk of stone disease correlates with weight and body mass index.
1-Low urinary volumes.
2-High rates of calcium, oxalate, phosphate, or urate
3- Low citrate and magnesium excretion .
acts as an inhibitor of calcium oxalate and calcium phosphate stone formation by a variety of actions:
1- it complexes with calcium, reducing the
availability of ionic calcium to interact with oxalate or phosphate
2- It directly inhibits the spontaneous precipitation of calcium oxalate and prevents the agglomeration of calcium oxalate crystals.
it has limited inhibitory effect on calcium oxalate crystal growth , more potent activity in reducing calcium phosphate growth.
3- citrate prevents heterogeneous nucleation of calcium oxalate by monosodium urate .
Its complexe with oxalate, which reduces ionic oxalate concentration and calcium oxalate supersaturation. In addition, magnesium reduces the rate of calcium oxalate crystal growth in vitro.
responsible for 25% to 50% of the inhibitory activity of whole urine against calcium phosphate crystallization.
1-Nephrocalcin is an acidic glycoprotein containing predominantly acidic amino acids that is synthesized in the proximal renal tubules and the thick ascending limb. In simple solution, nephrocalcin strongly inhibits the growth of calcium oxalate monohydrate crystals .
2. Tamm-Horsfall glycoprotein:
.syn - thick ascending limb & distal tubule
. inhibits aggregation CaOx- most potent
. Under specific condition, THP can promote
aggregation (high ionic strength, high calcium and
. Citrate can increase THP and its inhibitory effect
30% to 40 % of dietary calcium is absorbed from small intestine (the jejunum and the proximal portion of the ileum) and only approximately 10% absorbed in the colon.
absorption of calcium varies with calcium intake. with low calcium intake, calcium absorption is enhanced; during high calcium intake absorption is reduced.
Calcium in Plasma in three form :
1) combined with plasma proteins (40%)
2) combined with other substances but diffusible through capillaries (10%)
3) Ca++ (50%) active
1- Absorptive hypercalciuria due to increased intestinal absorption of calcium.
2- Renal hypercalciuria due to primary renal leak of calcium.
3- Resorptivehypercalciuria due to increased bone demineralization.
type I when urinary calcium remains high despite a low calcium diet (400 mg dietary calcium daily). type II when urinary calcium normalizes with a restricted calcium intake.
the underlying abnormality is primary renal wasting of calcium.
The consequent reduction in circulating serum calcium stimulates PTH production
Idiopathic hypercalciuria occurs in 5% to 10% of healthy people and in about half of patients with calcium nephrolithiasis.
the prevalence of stone disease in hyperparathyroidism is only about 1%.
therapy of RTA :.
First, patients tend to excrete excessively acidic urine at a relatively fixed, low urinary pH.
Second, they may absorb, produce, or excrete more uric acid than patients without gout or uric acid stones.
Third, urinary volume is diminished in these patients. The combination of these factors is ideal for the crystallization of uric acid in the urine.
Cystine is produced from the essential amino acid methionine, which is abundant in meat, poultry, fish, and dairy products. Thus, a low-methionine diet decreases urinary cystine excretion.
Scanning electron micrographs of various urinary crystals. A, Apatite; B,struvite; C, calcium oxalate dihydrate;D, calcium oxalate monohydrate;E,cystine; F, ammonium acid urate; G,brushite.
plain Kidney-Ureter-Bladder radiographs.
1. Pain not controlled with Po meds.
2. Calculus Anuria , usualy solitary kidney or bilat stones.
3. Infection , esp. when there is obstruction.