Litiasis en pediatría: correlación de métodos que dependen de la recogida de orina de 24 horas con otros más sencillos que no requieren orina minutada

IntroductionDaily practice requires quick, simple and accessible methods to appropriately assess the urinary excretion of solutes in diagnostic or follow-up evaluations of children with renal lithiasis.ObjectivesThe objective of this study was to correlate urine elimination of substances related to renal lithiasis that depend on the volume of excreted urine in a unit of time with other parameters that are calculated by measuring the concentration of these substances in blood and urine, such as urinary ratios, fractional excretions and excretion rates.Materials and methodsThe study included 401 healthy children aged 3-14 years (187 boys and 214 girls), mean age 8.78±3.40 years. The analysis was carried out by Pearson's correlation coefficient.ResultsThere was significant correlation between the elimination of sodium, potassium and chlorine in 24-hour urine sample and the urinary ratios and fractional excretions of these ions.Urinary ratios and rates of excretion of calcium, uric acid, phosphate, magnesium, citrate and oxalate were highly correlated with the determinations of these substances in 24-hour collections.ConclusionsThese equations provide relevant information for the study of the etiology of renal lithiasis in children, as well as about compliance to dietary treatment. They also assess the effectiveness of the various treatments used in these patients, without having to resort to 24-hour collections, which pose a considerable challenge in the pediatric age group.     

Long-term treatment of calcium nephrolithiasis with potassium citrate

The long-term effects of potassium citrate therapy (usually 20 mEq. 3 times daily during 1 to 4.33 years) were examined in 89 patients with hypocitraturic calcium nephrolithiasis or uric acid lithiasis, with or without calcium nephrolithiasis. Hypocitraturia caused by renal tubular acidosis or chronic diarrheal syndrome was associated with other metabolic abnormalities, such as hypercalciuria or hyperuricosuria, or occurred alone. Potassium citrate therapy caused a sustained increase in urinary pH and potassium, and restored urinary citrate to normal levels. No substantial or significant changes occurred in urinary uric acid, oxalate, sodium or phosphorus levels, or total volume. Owing to these physiological changes, uric acid solubility increased, urinary saturation of calcium oxalate decreased and the propensity for spontaneous nucleation of calcium oxalate was reduced to normal. Therefore, the physicochemical environment of urine following treatment became less conducive to the crystallization of calcium oxalate or uric acid, since it stimulated that of normal subjects without stones. Commensurate with the aforementioned physiological and physicochemical changes the treatment produced clinical improvement, since individual stone formation decreased in 97.8 per cent of the patients, remission was obtained in 79.8 per cent and the need for surgical treatment of newly formed stones was eliminated. In patients with relapse after other treatment, such as thiazide, the addition of potassium citrate induced clinical improvement. Thus, our study provides physiological, physicochemical and clinical validation for the use of potassium citrate in the treatment of hypocitraturic calcium nephrolithiasis and uric acid lithiasis with or without calcium nephrolithiasis.     

Dissolution of uric acid stones causing acute obstructing anuria in three consecutive infants

We report on 3 infants with obstructive anuria due to bilateral uric acid stones. In all patients the precipitating cause of acute obstructive renal failure was choking of bilateral ureteropelvic junction with numerous small uric acid stones without cause pelvicaliceal dilatation. While the chemical dissolution therapy succeeded in dissolving the stones in 2 patients, unilateral percutaneous nephrostomy application associated with alkalization achieved dissolution of obstructing stones in the remaining 1 patient.     

Management of uric acid renal obstruction by intravenous lactate

6 patients presenting with uric acid renal obstruction were managed by alkalization of urine using intravenous perfusion of 0.16 (1/6) M sodium lactate. Despite obstructive renal failure in 3 patients, rapid relief of obstruction was obtained and surgery was not necessary in any patient. Lysis of uric acid stones by urine alkalization is well documented [1, 4-12]. Intravenous infusion of 0.16 (1/6) M sodium lactate provides rapid urinary alkalization and is effective in the relief of obstruction by dissolution of uric acid calculi.     

Acute spontaneous tumor lysis presenting with hyperuricemic acute renal failure: clinical features and therapeutic approach

BACKGROUND: Acute spontaneous tumor lysis syndrome (STLS) presenting with hyperuricemic acute renal failure (ARF) is a rare disease which can be overlooked in patients with neoplasic disorders, requiring prompt recognition and aggressive management. This study examined the incidence, clinical characteristics and prognosis of this condition. METHODS: A retrospective study was performed, reviewing the records of all patients who developed ARF at Chang Gung Memorial Hospital between 1st July 1999 and 30th October 2002. Acute STLS was diagnosed based on pretreatment hyperuricemic ARF, ratio of urinary uric acid to creatinine (Cr) >1.0, and significantly elevated lactate dehydrogenase (LDH) (>500 units/L), together with a pathologically proven malignancy. Clinical course, metabolic parameters, response to therapeutics and outcome were assessed in all patients. RESULTS: STLS-induced acute uric acid nephropathy was identified in 10 out of 926 ARF patients (1.08%) studied. Most presentations were non-specific or related to malignancy symptoms. All patients had advanced tumors with large tumor burden, and abdominal organ involvement in 80% of patients. The 10 hyperuricemic patients became oliguric despite conservative therapy, and remained hyperuricemic (mean +/- SD: 20.7 +/- 5.0 mg/dL) until dialysis initiation. Seven patients (70%) developed diuresis, with an associated resolution of hyperuricemia, azotemia and metabolic derangements following dialysis initiation. The patients who developed diuresis had mean serum uric acid levels 9.3 +/- 3.1 mg/dL and median levels 9.8 mg/dL. Three patients (30%) survived, with two patients suffering residual renal function impairment. CONCLUSIONS: Acute STLS presenting with hyperuricemic ARF is a rare cause of acute uric acid nephropathy in patients with bulky or occult neoplastic disorders. The tumors that developed STLS had advanced stage or large tumor burden. Frequent abdominal organ involvement and non-specific initial presentations can obscure the nature of the disease and delay diagnosis. Unlike hyperuricemia and oliguria, which are constant findings, azotemia or impaired renal function is not always manifest on initial presentation. Poor outcomes in patients with STLS developing acute uric acid nephropathy make early recognition, aggressive management and prompt dialysis mandatory.     

Serum and urinary insulin-like growth factor-1 and tumor necrosis factor in neonates with and without acute renal failure

Acute renal failure (ARF) in neonates may occur after renal ischemia. Growth factors participate in the tubular regeneration process. Insulin-like growth factor-1 (IGF-1) is produced in the kidney during the recovery phase of ARF. Tumor necrosis factor-alpha (TNFα) may play a role in renal apoptosis. We examined serum and urinary IGF-1 and TNFα in neonates with or without ARF after asphyxia, in order to assess their possible use as markers of renal damage and recovery. We studied 20 full-term asphyxiated neonates, 10 with ARF and 10 without ARF, and compared them with 13 normal newborns for 7 days after birth. Blood urea, creatinine, pH, base deficit, and serum and urine IGF-1 and TNFα were assessed. Neonates with ARF had more-severe acidosis than patients without ARF. All patients had lower serum IGF-1 values immediately after birth than control children. Serum IGF-1 remained low in the ARF patients. The initial urinary IGF-1 was higher in all patients compared with control newborns, and remained elevated for the rest of the study only in the ARF neonates. Serum and urinary TNFα concentrations were similar for all healthy and diseased neonates. Measurement of serum and urinary IGF-1 levels in ARF neonates might be of additional value for clinical assessment of ARF. Received: 31 January 2001 / Revised: 30 October 2001 / Accepted: 7 January 2002     

Purine enzyme defects as a cause of acute renal failure in childhood

Acute renal failure (ARF) is not listed as a usual form of presentation in hypoxanthineguanine phosphoribosyltransferase deficiency, despite the gross uric acid overproduction in the defect. We found that a third of such patients may present in ARF when the urinary uric acid/creatinine ratio may be normal, not raised, and the defect may be suspected from the disproportionate increase in plasma uric acid. This is important in view of the potential confusion of uric acid with 2,8-dihydroxyadenine, the even more insoluble purine excreted in the other salvage enzyme disorder, adenine phosphoribosyltransferase deficiency. In that disorder, presentation in ARF is well recognised, the uric acid/creatinine ratio is also normal, but plasma urate is not raised. Our combined experience in these two disorders underlines the importance of early recognition and treatment with carefully adjusted doses of allopurinol, which may reverse or postpone renal failure.     

AN ENORMOUS ABDOMINAL MASS ASSOCIATED WITH ACUTE RENAL FAILURE

We report a 67-year-old man with acute uric acid nephropathy, secondary to spontaneous tumor lysis syndrome, that presented itself as a huge intra-abdominal tumor that led to acute renal failure, hyperuricemia, and azotemia. Initial finding of hydronephrosis detected by ultrasonography led us to believe that the azotemia and decreasing amount of urine resulted from obstructive uropathy, a common complication of malignancy, caused by either a direct renal invasion or a urinary outflow tract compression because of a tumor mass effect. However, clinical observations and the response to therapeutic intervention confirmed the diagnosis of spontaneous tumor lysis syndrome, which is a rare cause of acute uric acid nephropathy.     

Acute renal failure: nephrosonographic findings in asphyxiated neonates

To determine the incidence of acute renal failure (ARF) and nephrosonographic findings among asphyxiated neonates, and to correlate this with uric acid levels and the severity of hypoxic encephalopathy, we studied 80 full-term appropriate-for-date singleton neonates with perinatal asphyxia, and 30 healthy full-term neonates as controls from March 2006 to February 2007. A detailed history, thorough clinical examination along with investigations, including urine examination, 24-h urine collection, ultrasonography of abdomen and cranium, serum electrolytes, blood urea nitrogen, serum creatinine, and serum uric acid were obtained. ARF developed in 45% (36/80) of the asphyxiated neonates. Forty-eight (60%) neonates showed significant elevation of blood urea and 41 (51.3%) neonates had significant elevation of serum creatinine than the control group (P < 0.001). Sixty-two (77.5%) neonates developed significant elevation of serum uric acid levels, and nephrosonography revealed hyperechogenicity in all of them, while only two among the healthy neonates showed the raised uric acid levels (P < 0.001). Nonoliguric renal failure was seen 28/36 (77.8%) of the neonates with ARF, whereas eight (22.2%) neonates had oliguric renal failure. Eight (27.8%) patients among ARF patients maintained abnormal biochemical parameters after 2 weeks, and of whom four patients died after variable lengths of time with a mortality rate of 11.11%. Kidneys are the most common organs involved in perinatal asphyxia, and uric acid might be a causative factor for failure in addition to hypoxic insult. Routine use of kidney function test, along with abdominal ultrasonography form an important screening tool to detect any additional morbidity in these patients.     

An enormous abdominal mass associated with acute renal failure.

We report a 67-year-old man with acute uric acid nephropathy, secondary to spontaneous tumor lysis syndrome, that presented itself as a huge intra-abdominal tumor that led to acute renal failure, hyperuricemia, and azotemia. Initial finding of hydronephrosis detected by ultrasonography led us to believe that the azotemia and decreasing amount of urine resulted from obstructive uropathy, a common complication of malignancy, caused by either a direct renal invasion or a urinary outflow tract compression because of a tumor mass effect. However, clinical observations and the response to therapeutic intervention confirmed the diagnosis of spontaneous tumor lysis syndrome, which is a rare cause of acute uric acid nephropathy.     

Melamine-induced infant urinary calculi: a report on 24 cases and a 1-year follow-up

Melamine has been the main factor leading to infant urinary calculi occurring on a rather wide scale in China in 2008, which were the results of a rapid aggradation of metabolites such as cyanuric acid diamide, cyanuric acid, etc., causing uric acid stone to accumulate. Here, we present a report on 24 infants who were admitted to our department, their ages ranging from 3 to 10 months. All of these infants had a confirmed history of having been fed with the “Sanlu” brand milk powder, which contained excessive levels of melamine, with the highest being 2,563 mg/kg. The diagnosis, medical treatment and follow-up by ultrasonography at 1, 3, 6, 12 months were reported. 22 cases of these infants were rehabilitated after medical treatment and 1 infant underwent pyelolithotomy for relieving an obvious ureter obstruction. No recurrence was found in these babies thereafter. Another infant died from rapidly worsening renal failure. Therefore, this series of cases have demonstrated that melamine contained in the “Sanlu” milk powder was the main cause of these urinary stones. Urine alkalinization and stone liberalization were the most effective treatments. Fast diagnosis and treatment of acute obstructive urolithiasis may prevent the development of acute renal failure, which is associated with high morbidity and mortality rates.     

小儿多发性上尿路结石梗阻致急性肾功能衰竭的诊断及早期处理

目的：提高小儿上尿路多发性结石的诊断及早期治疗水平。方法：回顾性分析32例小儿上尿路多发性结石致急性肾功能衰竭的诊断及早期治疗过程，总结出较好的早期诊断与治疗的方法。结果：32例患者经腹部平片(KUB)及B超检查确诊27例，5例另行CT检查而确诊，32例患者均急诊处理，其中5例行输尿管镜碎石、4例经小儿膀胱镜置人小儿双J管而解除梗阻，23例经小儿膀胱镜置小儿双J管失败后，经常规手术解除梗阻，术后肾功能恢复良好。结论：小儿上尿路多发性结石致急性肾功能衰竭须早期诊断及治疗，KUB及B超检色是较好的诊断方法，应以简单、有效、创伤小的方法解除梗阻，可光用内镜方法治疗，如失败，则应急行常规手术解除梗阻。结石可留作Ⅱ期处理。     

Exercise-induced acute renal failure with renal hypouricemia: a case report and a review of the literature

A previously healthy 16-year-old boy developed acute renal failure following a track race at a local athletic meeting. Several hours after the run, he expressed pain in the loins with nausea and vomiting. After 3 sessions of hemodialysis, he was referred to our hospital. On admission, serum creatinine was elevated to 2.3 mg/dl without an increase in serum uric acid level. After recovery from acute renal failure (ARF), hypouricemia (0.7 mg/dl) became evident in the patient. One year later, he suffered from ARF after a track race with the highest creatinine levels of 1.1 mg/dl. In order to clarify the cause and prognosis of ARF with renal hypouricemia, we summarized the clinical features in 18 patients previously described and our patient. Serum uric acid levels after recovery from ARF were below 1.0 mg/dl in all patients. Renal biopsy in 9 patients showed acute tubular necrosis in 8 patients and uric acid nephropathy in 1. The short-term prognosis of these patients seemed good, although 5 patients needed to undergo hemodialysis in their ARF courses. However, the recurrence of ARF episodes occurred in 6 patients (31.6%) including our patient, indicating that prevention of ARF might be necessary in these patients. More information is required to establish guidance for prevention of ARF.     

Pathophysiologic basis for normouricosuric uric acid nephrolithiasis

BACKGROUND: Low urinary pH is the commonest and by far the most important factor in uric acid nephrolithiasis but the reason(s) for this defect is (are) unknown. Patients with uric acid nephrolithaisis have normal acid-base parameters according conventional clinical tests. METHODS: We studied steady-state plasma and urinary parameters of acid-base balance in subjects with normouricosuric pure uric acid stones. We also tested the ability of these subjects to excrete ammonium in response to an acute acid load. We compared these parameters in patients with pure uric acid stones to patients with mixed uric acid/calcium oxalate stones, pure calcium stones, and normal volunteers. RESULTS: Pure uric acid stone formers have a much higher incidence of either diabetes or glucose intolerance. After equilibration to a control diet, patients with uric acid stones have lower urinary pH and they excrete less of their acid as ammonium. This is compensated by higher titratable acidity and hypocitraturia. Despite their low baseline urinary pH, uric acid stone formers further acidify their urine after an acid load because of a severely impaired ammonia excretory response. Their characteristics are significantly different from normal volunteers and pure calcium stone formers. Patients with mixed uric acid/calcium stones exhibit intermediate characteristics. CONCLUSION: We propose that certain patients with normouricosuric uric acid nephrolithiasis have a renal acidification disease. The primary defect lies in renal ammonium excretion, which may be linked to the insulin-resistant state. Although net acid excretion is maintained at the expense of increased titratable acidity and to some degree hypocitraturia, the compromise is acid urine pH and may result in uric acid nephrolithiasis.     

Patients with renal hypouricemia with exercise-induced acute renal failure and chronic renal dysfunction

We here report the case of a 38-year-old male with back pain and vomiting occurring after exercise. Serum creatinine level was elevated, and he was admitted to our hospital with diagnosis of acute renal failure (ARF). He had experienced similar attacks at least 4 times, including the present episode, from the age of 22 years. After admission, the patient was managed only by resting, and remission was nearly attained in about 1 month. The renal biopsy specimen performed on day 15 showed findings of acute tubular necrosis, thickening of the tubular basement membrane, and interstitial fibrosis. After remission, the serum uric acid level was 0.7-0.8 mg/dl, fractional excretion of uric acid was 0.63, and the possibility of other diseases facilitating the excretion of uric acid was denied. Therefore, ARF associated with idiopathic renal hypouricemia was diagnosed. Since only mild responses were observed in a pyradinamide loading test and a benzbromarone loading test, the case was considered to be a presecretary reabsorption disorder type. Renal function tests showed the almost complete recovery of the glomerular filtration rate (GFR: 114 ml/min/1.73 m2), but the urine concentrating ability was markedly decreased (specific gravity 1.019 and osmolarity 516 mOsm/kgxH2O in Fishberg test). Past data from this patient indicated that this renal dysfunction had been persisting for ten years. We examined 9 patients with renal hypouricemia and focused on the differences between the two groups (with or without complications). Four patients had a history of exercise-induced ARF or calculus. The urine concentrating ability was significantly lower in these patients (group A) than in the other patients without complications (group B). The glomerular filtration rate in group A was within the normal range, but was lower than in group B. These results suggested the possibility that patients with renal hypouricemia with complications may have chronic renal dysfunction in the future.     

慢性尿酸性肾病致肾功能损害患者的临床诊治研究

目的：探讨慢性尿酸性肾病致肾功能损害患者的临床诊治方法。方法选取本院2011年10月～2013年10月诊治的慢性尿酸性肾病致肾功能损害患者83例,根据治疗方案分为两组,41例患者实施常规治疗为对照组,42例患者加用别嘌呤醇为观察组,疗程8周,比较两组患者相关临床指标的改变情况、临床疗效、不良反应情况。结果治疗后,对照组患者血尿酸显著下降,而尿pH值显著升高。观察组患者血尿酸、血肌酐、尿素氮、24h尿蛋白均显著下降,而肾小球滤过率、尿pH值均显著升高。观察组患者血尿酸、血肌酐、尿素氮、24h尿蛋白均明显低于对照组,观察组患者肾小球滤过率、总有效率均明显高于对照组,差异均有统计学意义（P＜0.05）。结论别嘌呤醇是治疗慢性尿酸性肾病致肾功能损害的有效药物,可明显改善患者的临床指标,提高治愈率,引发的不良反应少,具有较高的安全性,值得临床推广使用。     

Urinary excretion of urodilatin in healthy children and children with renal disease

Urodilatin (URO) is a natriuretic peptide isolated from human urine which is thought to be produced by distal tubular cells. We measured urinary URO excretion in 50 healthy children and 23 children with acute (ARF), chronic renal failure (CRF), or hereditary tubular disorders, using a specific radioimmunoassay. The mean URO excreted in these four groups was 56, 45, 94, and 121 fmol/min per 1.73 m², respectively (differences between first three groups not significant). The variation in URO excretion was larger in patients with kidney disease than in controls. There were significant correlations between urinary URO and sodium excretion in controls and CRF, but not in ARF. URO excretion also correlated with urine flow rate in CRF. Although no correlation was found between URO excretion and creatinine clearance, urinary URO was increased in some patients with advanced CRF, which suggests stimulated tubular production to compensate for reduced sodium excretion. In view of the therapeutic potential of URO in renal insufficiency, further study of the renal handling of URO is warranted. Received December 4, 1996; received in revised form and accepted June 13, 1997     

Furosemide-Induced Increase in Urinary and Peritoneal Excretion of Uric Acid During Peritoneal Dialysis in Patients with Chronic Uremia

Intermittent peritoneal dialysis was performed in 17 patients with chronic uremia in order to observe the effect of furo-semide added to the dialysate on urinary and peritoneal elimination of uric acid. Two kinds of dialysate were used: moderately hypertonic (osmolality, 431.2 mOsm/kg of water) and slightly hypertonic (osmolality, 368.9 Osm/kg of water). Significant increases in urine volume, urinary and peritoneal excretion of uric acid, and renal and peritoneal clearances were found. The increase in urinary excretion of uric acid exceeded that of urine volume. These findings were interpreted to be the result of furosemide action on renal function after being transferred through the peritoneum into the blood stream with the concomitant increase in the uric acid shift from the circulation into the peritoneal cavity. We concluded that the addition of furosemide is useful in increasing uric acid elimination in patients with chronic uremia.     

Percutaneous nephrostomy and emergency drainage in obstructive anuria

Sonography seems in patients with acute renal failure a reliable method for diagnosing urinary tract obstruction, giving the kidney size and localizing the kidney for percutaneous drainage. Percutaneous nephrostomy is actually the best temporary derivation for patients with obstructive anuria before definitive treatment. 18 cases of obstructive anuria are reviewed. Urinary lithiasis is the main aetiology (13/18). 11 of our patient had undergone percutaneous nephrostomy as a first step of their treatment.     

Renal hypouricemia in school-aged children: screening of serum uric acid level before physical training

We present two cases of a 12-year-old Japanese boy and a 14-year-old Japanese girl who had exercise-induced acute renal failure (ARF). They experienced general fatigue, nausea/vomiting, and vague discomfort in the abdomen after physical exercise at school. In case of the boy, abdominal pain subsided, but renal dysfunction lasted 17 days, with peak levels of creatinine 9.4 mg/dl and uric acid 11.3 mg/dl. On the other hand, as the girl had suffered from hypouricemia before, she followed a doctor’s guidance on prevention of ARF. Consequently, she was promptly diagnosed as having exercise-induced ARF associated with hypouricemia, and rapidly recovered from ARF within a week. The difference between their clinical courses suggested a possibility that previous laboratory evaluation of serum uric acid assisted in the management of exercise-induced ARF associated with hypouricemia. School-aged children, especially Japanese and Asian, may be advised to have their serum uric acid measured before starting physical training at school.