Urolithiasis: Causes and Treatments

Introduction

Urolithiasis, or kidney stone disease is associated with the development of solid material within the urinary tract, where substances in the form of crystals gradually increasing in size over time. When kidney stones become too big, obstructions within the urinary tract can occur, resulting in the blockage in the flow of urine, resulting in extreme pain and increasing chances of kidney damage. Currently, there has been in increase in urolithiasis within North America, with prevalence doubling over the past 3 decades, with noted increases in most of European and Asian countries. As many as one in 11 Americans develop nephrolithiasis, and over the past 15 years the prevalence has increased by almost 70%. With this increased rate of prevalence worldwide, urolithiasis has become increasingly recognized as a systemic disorder, being associated with chronic kidney disease nephrolithiasis-induced bone disease, increased risk of coronary artery disease, hypertension, type 2 diabetes mellitus, and the metabolic syndrome (MS). Without medical treatment, nephrolithiasis is a chronic illness with a recurrence rate greater than 50% over 10 years. Given that the annual expenditure in the United States exceeds $5 billion, the economic and social burden of nephrolithiasis is immense.

Evaluation

Acute renal colic presents as cramping and intermittent abdominal and flank pain as kidney stones travel down the ureter from the kidney to the bladder.[1] Pain is often accompanied by nausea, vomiting, and malaise; fever and chills may also be present.[1]  The initial workup of a patient with suspected kidney stones in the primary care setting should include point-of-care urinalysis to detect blood, because hematuria aids in the confirmation of diagnosis.[1] Imaging is an important diagnostic tool and is the initial step in deciding which therapeutic or surgical options to use for the management of kidney stones. At initial presentation of symptoms associated with urolithiasis, a non-contrast computerized tomography scan (CT scan) is the preferred imaging method due to its high sensitivity and specificity for the detection of kidney stones. CT broadly refers to many types of imaging scans with differing amounts of contrast or even none at all, and variable image timing depending on the clinical question to be answered. CT exploits the different degrees to which body tissues absorb radiation. Multiple data points are obtained by rotating a radiation source and contralateral detector around the patient, these data are processed by a computer into 3D images. In patients with nephrolithiasis, noncontrast CT or CT-KUB radiography are most often used. As kidney stones have a markedly different composition compared with renal parenchyma and urine, they absorb considerably more radiation and are easily identifiable without the need for contrast. CT generates a 3D image of the stone and the surrounding anatomy, which can be reconstructed into multiple viewing planes. The sensitivity of CT for detecting kidney stones is the highest of all the available modalities and reasonable estimates suggest it is ~95%.

Treatment (Needs work)

The treatment of urolithiasis is large dependent on the characteristics of the kidney stone. Characteristics of interest that dictates clinical decisions by urologists is dependent on size and type of stone, the location of the kidney stone within the urinary tract, as well as the patient characteristics. If the stone is small, patients may pass the stones themselves within surgical interventions. However, if the stone is too large to pass and pain is experienced, urologists may suggest surgical procedures within the hospital setting to remove the stone.

If the stones don’t pass out of the body on their own, they can be broken up or removed in a minor surgical procedure. Referral to a urologist for active stone removal is warranted when the stone is larger than 10 mm or if significant hydronephrosis is present.[2] With urolithasis having a prevalence rate of 9% in North America, it is estimated that 25% of these patients will require a surgical intervention to remove stones.[3] 0 In the last 3 decades the surgical management of kidney stones has undergone many technological advances with the development of extracorporeal shockwave lithotripsy (SWL), rigid and flexible ureteroscopy (URS), and percutaneous nephrolithotomy (PCNL).[4] . Many urologic organizations have provided evidence-based guidelines to define the role of each modality in the surgical management of urinary stones and help the urologist make therapeutic choices.[4] . Unfortunately, the methods used to develop these recommendations may vary among guideline panels. Moreover, with the constant release of new scientific publications guidelines quickly become outdated and require frequent updating.[5]

PCNL Tx

Prior to the performance of PCNL, Clinicians should obtain a non-contrast CT scan on patients prior to performing PCNL.[6] As determined by the urologist, patients who are unlikely to have successful results with SWL and/or URS, PCNL is warranted.[6] Furthermore, symptomatic patients with a total renal stone burden >20 mm, clinicians should offer PCNL as first-line therapy.

References:

1. Frassetto L, Kohlstadt I. Treatment and prevention of kidney stones: an update. Am Fam Physician. 2011;84(11):1234-1242.
2. Türk C, Petřík A, Sarica K, et al. EAU guidelines on diagnosis and conservative management of urolithiasis. Eur Urol. 2016;69(3):468-474.
3. Saigal CS, Joyce G, Timilsina AR et al: Direct and indirect costs of nephrolithiasis in an employed population: opportunity for disease management? Kidney Int 2005; 68: 1808.
4. Benjamin Pradère, Steeve Doizi, Silvia Proietti, Jan Brachlow, Olivier Traxer, Evaluation of Guidelines for Surgical Management of Urolithiasis, The Journal of Urology, Volume 199, Issue 5, 2018, Pages 1267-1271.
5. Pietropaolo A, Proietti S, Geraghty R et al: Trends of ’urolithiasis: interventions, simulation, and laser technology’ over the last 16 years (2000- 2015) as published in the literature (PubMed): a systematic review from European section of Urotechnology (ESUT). World J Urol 2017; 35: 1651.
6. Assimos D, Krambeck A, Miller NL, et al. Surgical Management of Stones: American Urological Association/Endourological Society Guideline, PART I. J Urol. 2016;196(4):1153-60.