Urolithiasis and Nephrolithiasis PDF

10/19/23, 3:44 AM Realizeit for Student UROLITHIASIS AND NEPHROLITHIASIS Urolithiasis and nephrolithiasis refer to stones (calculi) in the urinary tract and kidney, respectively. Urinary stones predominantly occur in the third to fifth decades of life and affect men twice as often as women (Norris...

10/19/23, 3:44 AM Realizeit for Student UROLITHIASIS AND NEPHROLITHIASIS Urolithiasis and nephrolithiasis refer to stones (calculi) in the urinary tract and kidney, respectively. Urinary stones predominantly occur in the third to fifth decades of life and affect men twice as often as women (Norris, 2019). The prevalence of renal calculi is 10.6% for males and 7.1% for females; however, recent studies show that rates are increasing among women with estimates that the ratio of affected males-to-females is 1.3 to 1 (Flagg & Joiner, 2017). Stones may develop in one or both kidneys (Norris, 2019). Pathophysiology Stones are formed in the urinary tract when urinary concentrations of substances such as calcium oxalate, calcium phosphate, and uric acid increase. Referred to as supersaturation, this depends on the amount of the substance, ionic strength, and pH of the urine. Stones may be found anywhere from the kidney to the bladder and may vary in size from minute granular deposits, called sand or gravel, to bladder stones as large as an orange. The different sites of calculi formation in the urinary tract are shown in Figure 49-5 . Certain factors favor the formation of stones, including infection, urinary stasis, and periods of immobility, all of which slow kidney drainage and alter calcium metabolism (Norris, 2019). In addition, increased calcium concentrations in the blood and urine promote precipitation of calcium and formation of stones (the most common are calcium based) (Norris, 2019). Causes of hypercalcemia (high serum calcium) and hypercalciuria (high urine calcium) may include the following (Norris, 2019): Hyperparathyroidism Renal tubular acidosis Cancers (e.g., leukemia, multiple myeloma) Dehydration Granulomatous diseases (e.g., sarcoidosis, tuberculosis), which may cause increased vitamin D production by the granulomatous tissue Excessive intake of vitamin D Excessive intake of milk and alkali Myeloproliferative diseases such as polycythemia vera, which produce an unusual proliferation of blood cells from the bone marrow Intestinal bypass surgery https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=0Dn26kXyU%2f6F5gOCz4%2f2IcdpKuauTn1W0lrWmCsonBYnaQIwEDgwdbmVgOEy99af… 1/4 10/19/23, 3:44 AM Realizeit for Student For patients with stones containing uric acid, struvite, or cystine, a thorough physical examination and metabolic workup are indicated because of associated disturbances contributing to the stone formation. Uric acid stones account for 72% of stones in men (Flagg & Joiner, 2017). These may be seen in patients with gout or myeloproliferative disorders. Seventy-two percent of stones diagnosed in women are struvite stones (Flagg & Joiner, 2017) which form in persistently alkaline, ammonia-rich urine caused by the presence of bacteria such as Proteus, Pseudomonas, Klebsiella, Staphylococcus, or Mycoplasma. Predisposing factors for struvite stones include neurogenic bladder, foreign bodies, and recurrent UTIs (Norris, 2019). Several conditions, as well as certain metabolic risk factors, predispose patients to stone formation. These include anatomic derangements such as polycystic kidney disease, horseshoe kidneys, chronic strictures, and medullary sponge disease. Urinary stone formation can occur in patients with inflammatory bowel disease and in those with an ileostomy or bowel resection because these patients https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=0Dn26kXyU%2f6F5gOCz4%2f2IcdpKuauTn1W0lrWmCsonBYnaQIwEDgwdbmVgOEy99af… 2/4 10/19/23, 3:44 AM Realizeit for Student absorb more oxalate. Medications known to cause stones in some patients include antacids, acetazolamide, vitamin D, laxatives, and high doses of aspirin (Comerford & Durkin, 2020). However, in many patients, no cause may be found. Clinical Manifestations Signs and symptoms of stones in the urinary system depend on the presence of obstruction, infection, and edema. When stones block the flow of urine, obstruction develops, producing an increase in hydrostatic pressure and distending the renal pelvis and proximal ureter (Norris, 2019). Infection (pyelonephritis and UTI with chills, fever, and frequency) can be a contributing factor with struvite stones. Some stones cause few, if any, symptoms while slowly destroying the functional units (nephrons) of the kidney; others cause excruciating pain and discomfort (Flagg & Joiner, 2017). Stones in the renal pelvis may be associated with an intense, deep ache in the costovertebral region. Hematuria is often present; pyuria may also be noted. Pain originating in the renal area radiates anteriorly and downward toward the bladder in the female and toward the testes in the male. If the pain suddenly becomes acute, with tenderness over the costovertebral area, and nausea and vomiting occur, the patient is having an episode of renal colic. Diarrhea and abdominal discomfort are due to renointestinal reflexes and the anatomic proximity of the kidneys to the stomach, pancreas, and large intestine. Stones lodged in the ureter (ureteral obstruction) cause acute, excruciating, colicky, wavelike pain that radiates down the thigh and to the genitalia. Often, the patient has a desire to void, but little urine is passed, and it usually contains blood because of the abrasive action of the stone. This group of symptoms is called ureteral colic. Colic is mediated by prostaglandin E, a substance that increases ureteral contractility and renal blood flow and that leads to increased intraureteral pressure and pain. In general, the patient is able to pass stones 0.5 cm in diameter (Norris, 2019). Stones larger than 1 cm in diameter usually must be removed or fragmented (broken up by lithotripsy) so that they can be removed or passed spontaneously. Stones lodged in the bladder usually produce symptoms of irritation and may be associated with UTI and hematuria. If the stone obstructs the bladder neck, urinary retention occurs. If infection is associated with a stone, the condition is far more serious, with the potential for urosepsis developing. Assessment and Diagnostic Findings The diagnosis is confirmed by a noncontrast CT scan (Flagg & Joiner, 2017). Blood chemistries and a 24-hour urine test for measurement of calcium, uric acid, creatinine, sodium, pH, and total volume may be part of the diagnostic workup. Dietary and medication histories and family history of renal calculi are obtained to identify factors predisposing the patient to the formation of stones. https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=0Dn26kXyU%2f6F5gOCz4%2f2IcdpKuauTn1W0lrWmCsonBYnaQIwEDgwdbmVgOEy99af… 3/4 10/19/23, 3:44 AM Realizeit for Student When stones are recovered (whether freely passed by the patient or removed through special procedures), chemical analysis is carried out to determine their composition. Stone analysis can provide a clear indication of the underlying disorder. For example, calcium oxalate or calcium phosphate stones usually indicate disorders of oxalate or calcium metabolism, whereas urate stones suggest a disturbance in uric acid metabolism (Flagg & Joiner, 2017). https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=0Dn26kXyU%2f6F5gOCz4%2f2IcdpKuauTn1W0lrWmCsonBYnaQIwEDgwdbmVgOEy99af… 4/4