For the purpose of the article, the terms urolithiasis, nephrolithiasis and renal/ kidney stones are used interchangeably, although some authors have slightly. 13 dez. Litíase Renal Etiologia Patogenia Objetivos do trabalho epidemiologia etiologia patogenia tratamento alterações funcionais e/ou morfológicas. Litíase Renal. BS. Beatriz Santos. Updated 19 May Transcript. Litíase Renal. Excesso de cálcio; oxalato;. ácido úrico; cistina na urina.

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Urolithiasis refers to the presence of calculi anywhere along the course of the litixse tracts. By far the most common stone is calcium oxalate, however, the exact distribution of stones depends on the population and associated metabolic abnormalities e. Although some renal stones remain asymptomatic, most will result in pain.

Small stones that arise in the kidney are more likely to pass into the ureter where they may result in renal colic.

The composition of urinary tract litaise varies widely depending upon metabolic alterations, geography and presence of infection, and their size varies from gravel to staghorn calculi. The more common composition of stones include more detail below:.

Most renal calculi contain calcium, usually in the form of calcium oxalate CaC 2 O 4 and often mixed with calcium phosphate CaPO 4 1,6.

Urinary lithiasis: the perfect balance

In most instances, no specific cause can be identified, although most patients have idiopathic hypercalciuria without hypercalcaemia. Brushite is a unique form of calcium phosphate stones that tends to recur quickly if patients are not treated aggressively with stone prevention measures and are resistant to treatment with shock wave lithotripsy.

Interestingly hyperuricosuria is also associated with increased calcium containing stone formation and is thought to be related to the uric acid crystals acting as a nidus on which calcium oxalate and calcium phosphate can precipitate 6. Rarely the underlying cause is primary oxaluriaa liver enzyme deficiency leading to massive cortical and medullary nephrocalcinosisand renal failure. Certain medications 14 can predispose to calcium oxalate or calcium phosphate calculi, including:.


Struvite magnesium ammonium phosphate or “triple phosphate” stones are usually seen in the setting of infection with urease-producing bacteria e. Proteus, Klebsiella, Pseudomonas and Enterobacterresulting in hydrolysis of urea into ammonium and increase in the urinary pH 6, They can grow very large and form a cast of the renal pelvis and calyces resulting in so-called staghorn calculi.

Uric acid and cystine are also found as minor components. Hyperuricosuria is not always associated with hyperuricaemia and is seen in a variety of settings see abovealthough in most instances uric acid stones occur in patients with no identifiable underlying etiology 6. Uric acid crystals form and remain insoluble at acidic urinary pH below 5.

Cystine stones are also formed in acidic urine and are seen in patients with congenital cystinuria. These depend on stone composition and vary according to modality. The much greater sensitivity of CT to tissue attenuation means that some stones radiolucent on plain radiography are nonetheless radiopaque on CT.

It involves administration of intravenous contrast. This exam has been largely replaced by non-contrast CT. Ultrasound is frequently the first investigation of the urinary tract, and although by no means as sensitive as CT, it is often able to identify calculi. Small stones and those close to the corticomedullary junction can be difficult to reliably identify. Ninety-nine percent of renal tract calculi are visible on a non-contrast CT. Given that one of the commonest sites for a stone to become lodged is the vesicoureteric junction, some centres perform the study in the prone position to establish if the stone is retained within the intravesical component of the ureter or has already passed into the bladder itself.

DECT is a technique allowing determination of calculus composition, by assessing stone attenuation at two different kVp levels.

Each CT vendor has its own algorithms for the use of dual energy CT for assessing stone composition. Irrespective of stone composition, patients who present with renal colic require assessment. This is of course provided that the kidney is not obstructed and infected in which case a percutaneous nephrostomy should be performed on an emergency basis to save the organ and prevent sepsis. Small asymptomatic stones in the kidney can be safely ignored, and if patients maintain good states of hydration, the risk of recurrent symptoms can be dramatically reduced Struvite stones are usually large staghorn calculi and result from infection.


These stones need to be treated surgically and the entire stone removed, including small fragments, as otherwise, these residual fragments act as a reservoir for infection and recurrent stone formation.

Urolithiasis | Radiology Reference Article |

Uric acid stones usually are the result of low urinary pH, and hydration and elevation of litase pH to approximately 6 is usually sufficient note rendering the urine too alkali e. Cystine stones may be difficult to treat and are difficult to shatter with ESWL.

Hydration and alkalinisation are usually first line therapy.

The differential of renal calculi is essentially that of abdominal calcifications. On CT there is usually little confusion as not only is CT exquisitely sensitive in detecting stones, but liriase location can also be precisely noted. If non-contrast CT is equivocal for the location of the calcification, then a repeat CT with urographic phase contrast is usually able to clarify.

Thus the differential diagnosis is predominantly on plain radiograph, and to a lesser degree ultrasound:. To quiz yourself on this article, log in to see multiple choice questions. You can also scroll through stacks with your mouse wheel or the keyboard arrow keys. Unable to process the form.

Check for errors and try again. Thank you for updating your details. Log in Sign up. Articles Cases Courses Quiz. About Blog Go ad-free. Evaluation litase the patient with flank pain and possible ureteral calculus. Edit article Share article View revision history. Synonyms or Alternate Spellings: Support Radiopaedia and see fewer ads. Figure 1 Figure 1.

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