Renal Stones DR. Gehan Mohamed

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Renal StonesDR. Gehan Mohamed
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Learning objectives

• 1- define renal stones and know the alternative
  names.
• 2- understand the causes and risk factors for
  the formation of nephrolithiasis.
• 3- mention the Inhibitors of Spontaneous
  Crystallization in urine.
• 4- list the different types of renal stones
• 5- understand cause , site of the renal colic.
• 6- mention the important investigations needed
  for diagnosis of nephrolithiasis.
• 7- list complications and methods of treatment
  for renal stones.

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How is Urine formed?1- blood filteration through
glomeruli2- tubular reabsorption3- tubular
secretion
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Kidney Stones

• Definition are hard deposits of mineral and
  acid salts on the inner surfaces of the kidneys
• Alternative names include
• Renal Lithiasis
• Nephrolithiasis (Kidney Stone Disease)
• Renal Calculi
• Stones are classified by
• - Their location in the urinary system
• - Their composition of crystals.
• - Their size either small or large.

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Inhibitors of Spontaneous Crystallization

• Normal urine contains chelating agents(i.e agents
  have ability to make bonds with another
  substances) such as citrate that inhibit the
  nucleation, growth, and aggregation of
  calcium-containing crystals.
• Other endogenous inhibitors include calgranulin
  (an S-100 calcium binding protein), Tamm-Horsfall
  protein

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Causes of Stone formation

• 1-Supersaturation of urine either due to
  Dehydration or due to increase level of minerals
  in urine such as (Ca,oxalate) ,uric acid lead
  to Crystal aggregation
• 2- Bacterial Infection
• - E.Coli infection increases protein matrix
  content in urine
• - Proteus makes urine alkaline as it split
  urea into amonia making alkaline urine so
  fascilitate deposition of magnesium ammonium
  phosphate crystals (struvite stone).
• 3-Imbalance of pH in urine
• Acidic Uric acid,calcium oxalate Stones
• Alkaline Calcium phosphate Stones
• 4-Anatomic Abnormalities as Pelviureteric
  junction stenosis leading to urine stasis.

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Risk Factors for renal stones

• 1-family history is a factor in certain forms of
  stone disease such as cystinuria which is an
  inherited metabolic disorder.
• 2- Occupation activities that keep people out in
  hot weather and increased sweating as in
  construction work, farming .
• 3- Diet
• - Low fluid intake lead to
  supersaturation of urine
• - high dietary intake of
• - animal protein produce purine
  which change to uric acid
• - refined sugars, fructose
• - grapefruit juice rich in vitamen C
  (ascorbate) which have the ability to change to
  oxalate.
• 4- drugs as diuretics can cause dehydration.

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Risk Factors

• 5- crohns disease are associated with
  steattorhea, The fatty acids in the gut bind with
  intraluminal calcium leaving the oxalate to be
  absorbed by blood. net effect is hyperoxaluria.
• 6- HYPERCALCAEMIA HYPERCALCIURIA either due to
  
• - some diseases associated with
  hypercalcemia as hyperparathyroidism,sarcoidosis
  ,hyperthyroidism,myeloma,Vit. D
  Intoxication,Metastatic Malignant Neoplasms.
• - while excessive supplemental calcium in
  diet do not appear to cause kidney stones and may
  actually protect against their development.This
  is perhaps related to the role of oral calcium in
  binding ingested oxalate in the gastrointestinal
  tract and prevent its reabsorption by blood so
  prevent hyperoxaluria and stone formation.

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structure of Renal Stones

• all urinary stones are composed of
• crystalline material 98 which have a very
  limited solubility in urine .
• mucoprotein 2 (matrix)
• N.B The stone with branches formed within calyxes
  and pelvis is termed stag horn-like or
  coral-like stone

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Stag horn stone is the stone with branches
formed within calyxes and pelvis is termed
stag horn-like or coral-like stone
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Types of Renal Stones (cont.)

• 1- calcium oxalate (75) need acidic urine.
• 2- calcium hydroxyl phosphate (15) need
  alkaline urine.
• 3- struvite magnesium ammonium phosphate
  10 is found mostly in women because of their
  increase chance of having chronic pyelonephritis.
  
• 4- Uric acid stone (5 )
• - occur in acidic urine with PH
  below 7 leading to crystal formation.
• - common in patients with gout,high
  protein diet ,chemotherapy treatment.
• - It is the only type that is truly
  radiolucent (can not be seen on a plain abdominal
  film.
• 5- Cystine stones ( 1) of stones due to
  genetic abnormality in its metabolism leading to
  its leak through the kidneys and into the urine
  to form crystals.
• .

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Calcium oxalate stones
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Stained and unstained microscopic image of a
calcium oxalate stone in urine
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Calcium phosphate stones
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Uric acid stone and shape of its crystals in urine
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Cystine stones and shape of its crystals in urine
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Commonest Site of Stone Development

• Question Where in the Urinary Tract does urine
  reach its maximal concentration and can get
  stuck in the lumen?
• Answer at the collecting duct in the renal
  papilla serves as the uterus for stone
  formation. It is here that urine has achieved
  its maximum concentration and hence is most
  likely to be supersaturated. Clumps of crystals
  become impacted in the opening of a collecting
  duct so that some of the crystals are now exposed
  to the urine in that calyx that comes from other
  collecting ducts

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Excretion of urine from body is essential to get
rid of excess body fluids, excess electrolytes
and waste products
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Diagnosis of renal calculi

• Clinical pictures.
• urine analysis
• radiographic studies

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Clinical Features

• Asymptomatic if the stone donot cause any
  obstruction.
• Severe flank pain colicky in nature (comes and
  goes in spasmodic waves). Pain in the back occurs
  when calculi produce an obstruction in the kidney
  or pain caused by peristaltic contractions of the
  ureter as it attempts to expel the stone
• flank pain referred to genitalia
• nausea, vomiting may mislead
• Microhematuria if stone have rough surface.

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Clinical picture of renal calculi
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investigations

• Urine analysis hematuria, infection,type of
  crystals.
• X - Ray most of renal stones are radiopaque due
  to calcification except uric acid stones are
  radiolucent so not seen.
• Intravenous urography(IVU) will show delayed
  function, hydronephrosis and ureteral dilatation
  to point of stone
• Ultrasound can show hydronephrosis, stones.

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Struvite crystals found on microscopic
examination of the urine
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X- Ray showing radio opaque stone
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Complications of renal stones

• 1- Calcular pyelonephritis
• 2-obstructive uropathy with Reflux nephrosis
• in the form of
• - Hydronephrosis - dilatation of renal
  pelvis ,calyces with atrophy of renal parenchyma
  due to lower obstruction . Then
  Hydronephrosis lead to 2ry infection due to
  stasis of urine producing Pyonephrosis
• So Pyonephrosis Hydronephrosis (dilatation)
  infection (pus)
• 3-Kidney damage, scarring leading to Postrenal
  azotemia, renal failure .

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Hydronephrosis
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hydronephrosis
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HydronephrosisHydroureter
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pyonephrosis
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pyonephrosis
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Pyonephrosis,pyoureter
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pyonephrosis
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pyonephrosis
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Medical Treatment for renal stones

• Adequate water intake to reach urine level per
  day about 2 litres as Drinking enough water
  helps keep urine diluted and flushes away
  materials that might form stones that is the most
  important thing a person can do to prevent kidney
  stones.
• Increase citrate intake present in lemon and
  orange juice . but citrus drinks may be helpful
  in preventing calcium oxalate stones and uric
  acid stones but they might be harmful for people
  who form calcium phosphate stones.
• limit vitamen C,sodium ,animal protein,excess
  flouride in water.
• Reducing salt intake is preferred to reducing
  calcium intake because Salt is made up of sodium
  and chloride. The sodium in salt, when excreted
  by the kidneys, causes more calcium to be
  excreted into the urine. High concentrations of
  calcium in the urine combine with oxalate and
  phosphorus to form stones.

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• Limit oxalate intake present in nuts, spinach,
  strawberries, nuts, dark chocolate, coffee and
  tea.
• Change PH of urine to increase solubilty of the
  solutes.
• Antibiotic intake with struvite type

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Surgical Treatment

• Surgery is usually needed if
• The stone is too large to pass on its own
• The stone is growing
• The stone is blocking urine flow and causing an
  infection or kidney damage
• The pain cannot be controlled

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treatment for renal stones

• 1- ESWL Extracorporeal shock-wave lithotripsy is
  used with stones smaller than a half an inch . It
  uses sound or shock waves to break up stones.
  Then, the stones leave the body in the urine.
• 2- Percutaneous nephrolithotomy using endoscope
  is used for large stones. The stone is removed
  with tube that is inserted into the kidney
  through a small surgical cut.
• 3- Ureteroscopy may be used for stones in the
  lower urinary tract.
• 4- open surgery (nephrolithotomy) may be needed
  if other methods do not work or are not possible.

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