STONE DISEASE Calculi are typically composed of urinary chemicals that are usually soluble - PowerPoint Presentation

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STONE DISEASE

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Calculi

are typically composed of urinary chemicals that are usually soluble in urine but occur in amounts too high to stay dissolved

Stones could be described according to the site (kidney, bladder, ureter, urethra) or

radiodensity

on KUB (radio opaque, radiolucent, relatively radiolucent) or the size and composition

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Calcium oxalate ..80%

Uric acid …5-10%

Calcium phosphate …10% mostly mixed

Struvite

…2-20%

Cystine

…1%

Others as drug

induced

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pathogenesis

The solution is considered

saturated

when reach the point at which the added salt crystals will not dissolve

The concentration at this point is called

saturation product,

In urine despite the concentration of stone forming component exceed the solubility product crystallization not necessary happen because of presence of inhibiters

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In this state of saturation the urine is considered

metastable

concentration at which no longer mount of crystal be dissolved and crystallization will happen is called

formation product

the urine above formation product is considered

unstable

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If urine is under saturated (below the solubility product )crystals will not form

If urine is unstable (above formation product) crystals will form

If urine is metastable (between the both product ) inhibiters will prevent crystallization in most of time

Under certain circumstances crystal will form if urine is metastable , first if there is obstruction in upper urinary tract, second heterogeneous nucleation presence of abnormal substance favor the crystal formation

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pathogenesis

In normal urine the solubility of calcium oxalate is 4 times higher than it’s solubility in water

This is because various inhibiters of crystallization (

citrate,GAG,Tamm-Horsfall

protein)

The

earliest phase of crystal formation is nucleation ,then aggregation process will start

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Epidemiology

The lifetime prevalence of kidney stones is 8.8% in USA

The peak incidence of stone disease is between (20-50) years

Gender: male to female ratio 1.4:1

Race: the highest prevalence of stone disease is between the whites

Prevalence: proportion of persons who have a condition in particular time

Incidence: proportion of person who develop a condition in particular time

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Geography: stone disease has higher prevalence in hot and dry climate, however the genetic and dietary influences outweigh the effect of geography

Occupation: workers who exposed to high temperature have higher risk of stone disease, also individual with sedentary occupation has higher risk of unknown reason.

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Obesity: obesity associate with increase excretion of oxalate and uric acid, also associate with lower urine PH.

Diet: high protein intake (high urinary oxalate),high salt intake cause

hypercalciuria

, low calcium diet ??

Water: high water intake decrease the incidence of stone disease

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Calcium oxalate stone

Calcium oxalate : dehydration,

hypercalciuria

,

hyperoxaluria

,

hypernatrituria

,

hypocitraturia

and

hyperuricosuria

Hypercalciuria

: increase absorption from GI like in high level of VIT D,

renal

hypercalciuria

: impaired renal reabsorption of calcium and so increase renal excretion of calcium,

lasix

(

furosmide

) inhibit calcium reabsorption and so

hypercalciurea

Resorptive

hypercalciuria

: primary hyperparathyroidism lead to excessive bone

resorption

and so high level of calcium

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Drugs: steroid increase bone

resorption

and reduce bone

formation

Hyperoxaluria

: primary

oxaluria

which is rare autosomal recessive disorder associate with high level of oxalate

Enteric

hyperoxaluria

: fat

malabsorption

leads to increase the attachment of fat with calcium and so more free oxalate and increase

it,s

absorption like in IBD and enteric bypass

Dietary

hyperoxaluria

: like chocolate and nuts, VIT C intoxication

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Hypocitraturia

: metabolic acidosis reduce urinary citrate level

Hyperuricosuria

: is associate with calcium oxalate stone by unknown mechanism and associate with uric acid stone , the most common cause is high dietary intake (meat) , gout and multiple myeloma, post

chemotharapy

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Uric acid stone

The three main determinant of uric acid formation low PH, low volume,

hyperuricosuria

Urin

PH is a critical factor in determining uric acid solubility, uric acid is less soluble in acidic urine (low PH), DM and obesity is associated with low urinary PH

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Cystine stone

cystinuria

is inherited autosomal recessive disorder characterized by decrease renal reabsorption of

cystine

amino acid

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Infection stone

Struvite

=infection=triple phosphate stone: is composed of magnesium ammonium phosphate

Bacterial urease convert urea into ammonia and carbon dioxide

This will result to alkaline urine which favor conversion of ammonia into ammonium

The alkaline condition also increase concentration of phosphate

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Proteus is the most common organism associate with infection stone

E coli rarely secretes urease

Infection stone is more in female

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Calcium phosphate stone

Distal renal tubular acidosis(type 1): inability to acidify the urine

inspite

of metabolic acidosis, due to abnormal collecting duct secretion of acid

Characterize by hypokalemia and

hyperchloremia

, metabolic acidosis and alkaline urine , calcium phosphate stone and

nephrocalcinosis

,

hypocitraturea

,

hypercalciurea

Acetozolamide

(carbonic anhydrase inhibiter diuretic): block bicarbonate absorption and so alkaline urine

wthe

calcium phosphate stone

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Urinary obstruction such as PUJS and hors shoe kidney associate with stasis and infection and so increase incidence of stone

Medullary sponge kidney:

ectasia

of renal collecting duct which associate with distal RTA and

hypercalciurea

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Kidney stones

May present with symptom or found incidentally

Symptoms include pain,

hematurea

,

Infection stone present with recurrent UTI, or infection complication

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Radiological assessment of kidney stone:

KUB: exposure from level of diaphragm to inferior pubic ramus, stone is classified according to appearance on KUB into:

Radio opaque: calcium phosphate and calcium oxalate

Relatively radiolucent:

struvite

,

cystine

Radiolucent: uric acid ,

indinavir

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Radio-opaque

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Semi-radiolucent

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stones

can be

characterised

by their size and

shape on KUB

Stone that occupy the renal pelvis and one or more renal calyces is called

staghorn

stone, which mostly composed of infection stone

stone

Limitation : stones could be obscured by overlying gas or bone, pelvic calcification could confused with ureteral stone, radiolucent stone does not appear on KUB

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3-size,

staghorn

stone…

.

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R

enal ultrasound : sensitivity to identify renal stone is variable, operator dependent

CT scan without contrast: the modality of choice to detect renal stone

It is more sensitive than KUB and provide anatomical information about the kidney and degree of HN

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radiolucent

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Small asymptomatic stone in older age group could be managed by watchful waiting

Struvite

stone is not suitable for watchful waiting because the risk of RI and sepsis.

The minimally invasive modality for stone fragmentation include SWL,URS,PCNL

Deciding the best treatment option depends on stone related factors, anatomical factors, clinical factors

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Treatment

1-

ESWL: extracorporeal fragmentation of stone

effects depend on stone size, location, anatomy of collecting system, and stone

composition

ESWL

is less effective in stone>1 cm ,lower pole stone or

calyceal

diverticulum stone and

cystine

stone and obese patient

Side effect of ESWL include

hematurea

or

perirenal

hematoma

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ESWL is contraindicated in:

Pregnancy

Bleeding tendency

Arterial aneurysm near the stone

Obstruction distal to the stone

Skeletal malformation

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ESWL

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3- Flexible ureteroscopy and laser :- in ESWL

failure,or

contraindicated , in lower pole stone less than 1 cm with

unfavourable

factors such as obesity

,

and hard stone

(

cystine

stone)

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2- PCNL:- in stone more than 2 cm, failed other modalities and anatomic

abnormality

The first line treatment in

staghorn

and stone more than 2 cm or lower pole stone more than 1 cm

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PCNL

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Flexible ureteroscopy

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4-laparoscopic or open

pyelolithotomy

rarely done

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medical

therapy ( dissolution therapy):-

uric acid stone are suitable for dissolution therapy

Dissolution therapy is based on hydration, urine

alkalinization

with potassium citrate, and allopurinol

Allopurinol inhibit xanthine oxidase and so decrease the level of uric acid

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Ureteric stone

Presents with ureteric colic, fever, hematuria, and RF

Acute management of ureteric colic is analgesia with narcotic or

NSAID better analgesic effect because it reduce the GFR and so the dilatation

Conservative management involve analgesia for pain exacerbation and medical expulsive therapy and waiting the stone to pass

spontaneosly

.

Example of MET alpha 1 blocker and calcium channel blocker.

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Factors that favor the passage of stone

Stone less than 5 mm

Lower ureteric stone

Less duration of symptom

Less degree of HN

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Indication of urgent intervention to

releive

obstruction or remove the stone :

Pain not responding to analgesia

Fever (obstructive pyelonephritis):

jj

stent

vs

nephrostomy

Impaired renal function: single kidney or

bil

ureteric obstruction

Prolonged unrelieved obstruction: more than 4 weeks

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Methods to

releive

the obstruction:

Jj

stent

nephrostomy

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JJ stent

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Nephrostomy

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Upper ureteric stone

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Middle ureteric stone

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Lower ureteric stone

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CTKUB

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Treatment

Treatment option for ureteric stone

ESWL: good option for upper ureteric stone less than 1 cm in size

Ureteroscopy

: semi rigid URS with intra corporeal fragmentation of the stone

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4-if more than 5mm according to size and sites:-

More than 10 mm whatever site best TX ureteroscopy and

intracorporal

lithotripsy

Less than 10 mm upper ureter.. Best

Tx

ESWL

Less than 10 mm mid ureter .. Best

Tx

URS

Less than 10 mm lower ureter .. Best

Tx

URS

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Intracorporal lithotripsy

1- pneumatic lithotripsy :- bursts of compressed air, safe, but stone

migration

Ultrasonic

lithotripsy:- break and suck stones, used in

PCNL

3-Laser

lithotripsy:- by

photo thermal

mechanism so stone vaporization, less stone

migration

4-Electrohydraulic

lithotripsy:-

Narrow safety margin,

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Evaluation of stone former

low risk stone former:

History about underlying condition, medication, diet and fluid intake

CBC and KFT with electrolyte, ca

lcium, PTH, uric acid,

urin

test for infection and PH

Radiography

Stone analysis

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High risk stone former:

Recurrent stone former

Strong family history

Gout

Osteoporosis

Single kidney

Inflammatory bowl disease

Infection,

cystine

, uric acid stone

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Workup for high risk stone former include: 24 hour urinary collection for calcium, oxalate, uric acid,

cystine

, and evaluation for RTA with the basic work up for low risk

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Dietary recommendation of stone former:

Increase in fluid intake( urine output at least 2 liters

Protein and salt restriction

Avoidance of oxalate( chocolate and nuts)

Moderate calcium intake

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Bladder stone

-mostly

struvite

( infected) or uric acid (non infection)

-

Tx

according to size :- if less than 3cm ..

Cystolitholapaxy

, if more than 3 cm ..

Cystolithotomy

-

Occure

in chronically catheterize patient or in BPH

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