Renal Stone. Hossein Hamidi MD. Isfahan university of Medical Sciences. Epidemiology. 12% of men and 5% of women develop symptomatic stone by the age of 70 . Rate of nephrolithiasis increases with : Age Men White . Etiology :. Calcium stones 80% ( Ca ox > Ca ph ) Uric acid
Hossein Hamidi MD.
Isfahan university of Medical Sciences
12% of men and 5% of women develop symptomatic stone by the age of 70 .
Rate of nephrolithiasis increases with :
One patient may have more than one type
(eg : Ca & uric acid )
There are two major factors that promote uric acid precipitation: a high concentration of uric acid; and an acid urine pHwhich drives the reaction toward uric acid formation,
at a urine pH of 7.0 (a setting in which 95 percent of uric acid is present as the more soluble urate anion)
the incidence of stone formation varies with the rate of uric acid excretion, ranging from 10 to 20 percent when urinary uric acid excretion is normal (upper limit of normal equals 800 mg [4.8 mmol] in men and 750 mg [4.5 mmol] in women) to as high as 40 to 50 percent when uric acid excretion exceeds 1000 mg/day (6 mmol/day) .
Wax & wane ( paroxysm of severe
pain lasts 20 – 60 min) .
Renal pelvic or upper ureter (flank
pain or tenderness) lower ureter
(ipsilateral testicle or labia )
The absence of hematuria in acute flank pain does not exclude nephrolithiasis
Struvite orCa ph crystalsalkaline urineCa ox crystalsPH. Independent
cystine crystal :hexagonal , struvite: mg.am.ph amm, ur. PH + UTI (proteus or klebsiella) = only struvite stone
* Detect : radiopaque stones ( Ca , struvite , cystine stones)
* Will miss : uric acid stone small stone stone overlying bony structures
* Will not detect : obstruction
2- non contrast helical CT scan due to higher sensitivity and specificity than IVP and US , suggest the initial diagnostic study of choice in most cases , and is faster than IVP and slightly more expensive ($ 600 vs $ 400 ). If helical CT is not available , IVP or US are appropriate .
1-hyperoxaluria and hyperuricosuria for ca ox . 2-urine PH > 5.3 , type 1 RTA for ca ph . Calcium stone formation is most often idiopathic but in other disorders :
1- persistent acid urine 2- overproduction of uric acid in gout 3- chronic diarrheal states
patients have Mg. Amm. Ph. crystal in urine. Stone may grow over a period of weeks or months , if not adequately treated develop a staghorn calculus .
Diag. :1- F.Hx. 2- hexagonal crystals on urinalysis in 25% of pts. 3- measurement of urinary cystine excretion .
Risk factors : fluid intake, animal protein , (hypercalciuria, hyperuricosuria , hypocitraturia),
salt diet , Ca intake , foods with oxalate? , Vitamin D .
Indinavir , Sulfadiazine , Triamterene .
Evaluation: 1- complete:
*multiple stones at first presentation
* active stone disease ( recurrent stone ,enlargement of old stone , passage of gravels )
2- limited :after first stone
3- targeted :first stone if : F Hx +ve, male, middle
age ,chronic diarrheal state and /or malabsorption
pathologic skeletal Fx. ,osteoporosis , UTO and/or gout,
stone composed of : cystine , uric acid , Ca ph, or struvite
citraturia, urine volume .
Diagnosis and medical treatment same as other stones .
initially at one year , if –ve every two or four yrs.
low bicarb : type 1 RTA . Ca measured on 2 or 3 occasions ,if high NL (10.2- 11) , or urine Ca is high : intact PTH should measured, since Primary HP is often associated with inttermi. or mildly elevated plasma Ca . PHP suspected in women , since PHP is more common in women , whereas 80% of formers of idiopathic stones are men .
urine volume , PH ,Ca , uric acid , citrate ,
oxalate , Na , Creatinine calculated . Two or
three separate collections to obtain all of these
informations . Uric acid in alkaline or plain solution , Ca
and Ox . in HCl or nitric acid solution ,Citrate in acidified solution ( needs 2or 3 sample and two or three 24 hr. urine collctions) .
Timing of collection :
interventionas ( ex : ESWL ) .
10% -20% require surgical management.
Stones < 5 mm pass spontaneously .
Stones > 8-10 mm pass unlikely .
Indication of stone removal :
Three surgical techniques :
proximal & renal stones SWL
middle & distal ureter ureterorenoscopy
ESWL ; treatment of choice in 85% of pts.
Medical therapy :
Medical therapy doesn’t dissolve preexisting Ca stones thus the passage of such stones can occur and does not represent a treatment failure.
Acute therapy :
Conservative : pain control , hydration , until stone passage. Average time for stone passage :
NSAID – Narcotics-Desmopressin
NSAID are as effective as opiates , but more pain relief at 10 min ( 100 mg rectal indomethacin vs. 5-10 mg IV morphine ). Or ; iv ketorolac (60 mg ) more pain relief vs.( 50 mg) iv meperidin
NSAIDs : 1- decreased ureteral smooth muscle tone
2- discourages opiate – seeking patients
3- may induce ARF
4- should be stop 3 days before SWL(because of bleeding ).
Intranasal Desmopressin : effective for renal colic .
Hospitalization :who can not tolerate oral intake or have very severe pain .
* failure to pass the stone after 2- 4 weeks
*stone > 5 mm
* uncontrolled pain
Chronic prevention of recurrent stones:
Monitoring of response :
Dietary modification :
Ca & Na reabsorption in proximal tubule
Ca excretion .
Limiting Ca intake not recommended .
A low Ca diet may have a second
deleterious effect in idiopathic
hypercalciuria ; wasting of Ca from the
bone and the kidney, results in diminished
bone density .
Indications :Active stone disease :
(Despite initial drug therapy over a six months
period ) .
Initial drug therapy :
Idiopathic hypercalciuria (not PHP or sarcoidosis )
urine Ca as much as 150 mg/d.
90% in incidence of new stones, dose 12.5-25mg/d . bone mineral density , hip fractures .
Idiopathic hypercalciuria : cont…
Ca reabsorption in CCT Ca excretion .
Plasma alkali Ca reabsorption Ca excretion.
Plasma alkali urine excretion of citrate .
Na causes volum expansion Na & Ca excretion.
crystalization inhibitors excretion ( pyrophosphate ).
Hyperuricosuria : if diet is ineffective :
stone formation .
urine PH > 6 insoluble uric acid to
soluble urate salt .
citrate excretion , Ca excretion not lower, Oxalate excretion modestly increased ( ascorbic acid )
tap water = 2 L/d (lemonade) urine Ca
urine Ox didn’t alter
Enteric hyperoxaluria :
No metabolic abnormality :
Ca Ph stones : have persistently urine PH , Treatment : K citrate .