原发性高草酸尿症3型8例病例系列报告并文献复习

背景：原发性高草酸尿症（PH）是一种罕见的由于先天性肝内乙醛酸代谢异常导致的遗传性肾结石/肾钙质沉着症,既往多关注1型和2型PH,PH3的致病基因HOGA1发现较晚,报告不多。 目的：总结PH3临床表型,探讨不同种族人群的PH3热点变异。 设计：病例系列报告。 方法：纳入2015年1月至2021年12月复旦大学附属儿科医院经HOGA1基因变异确诊为PH3的连续病例。从住院病史中采集临床和生物学检测信息,在PubMed、Embase、万方数据库和中国知网数据库中检索PH3病例的中、英文文献,采集病例来源（国家）、例数、性别、起病年龄、诊断年龄、起病临床表现（尿石症、肾钙质沉着症、高钙尿症、高草酸尿症）、随访时间、肾功能（慢性肾脏病2期、3期、4~5期）、随访年龄、尿路结石转归 (活动性结石、无症状结石或结石消失)、HOGA1基因变异位点。 主要结局指标：临床表型和不同种族人群的热点变异。 结果：纳入8例PH3患儿,男7例,女1例;起病年龄中位数10月龄,诊断年龄中位数16月龄。3例以肉眼血尿起病,5例以泌尿道感染起病。影像学均提示肾结石,均无肾钙质沉着表现。3例检测了24 h尿草酸,1例提示高草酸尿症;6例检测了尿钙,5例提示高钙尿症。1例失访,7例随访中位时间25个月,肾小球滤过率均维持稳定,3例肾结石消失。8例均检出HOGA1基因变异（共10个变异位点）,其中复合杂合变异5例,纯合变异3例,经ACMG分级判定6个位点为可能致病变异,4个位点为致病变异。中英文数据库共检索到82篇文献,筛选后23篇文献中321例PH3患者进入本文分析,中国36例（包括本文8例）,欧美293例。中国和欧美PH3患者：起病表现为尿石症的比例分别为83%(30/36)和85%(195/230),肾钙质沉着症分别为3%(1/29)和8%(20/261),高草酸尿症分别为90%(26/29)和96%(66/69),差异均无统计学意义;高钙尿症分别为44%(11/25)和23%（34/150),差异有统计学意义;末次随访时肾功能：中国1例PH3患者25岁时进展至终末期肾病,欧美2例PH3患者分别在8岁和33岁进展至终末期肾病;活动性结石：中国和欧美PH3患者分别为13%(3/23)和37%(22/59),差异有统计学意义。中国PH3患者热点变异为c.834G>A (splice site)、c.834_c.834+1GG>TT (splice site)和c.769T＞G (p.C257G),分别占28%(20/72)、21%(15/72)和11%(8/72);欧美PH3患者热点变异为c.700+5G>T (splice site)和c.944_946delAGG(p.E315del),分别占40%(236/586)和12%(73/586)。 结论：PH3起病年龄和诊断年龄较早,整体预后较PH1和PH2良好,中国与欧美PH3患者HOGA1基因突变可能存在不同的热点变异位点。     

Primary hyperoxaluria 1: catch up growth and normalization of oxaluria 6 years after hepatorenal transplantation in a prepubertal boy

We present data on urinary oxalate (U_OX), renal function, growth and bone age in a 10-year-old male with primary hyperoxaluria type 1. The patient had undergone combined liver-kidney transplantation at the age of 4.5 years. U_OX increased up to 10⁴ μmol/24 h after transplantation and declined to normal values thereafter. Excessive U_OX concentrations after surgery might have been due to a bone pool of unsoluble oxalate and declined spontaneously. Creatinine clearance remained stable during observation period. The boy showed significant catch up growth. Height standard deviation score for chronological age improved from −2.4 before transplantation to −0.3 after 6 years. Radiological bone density improved at the same time. Conclusion Hepatorenal transplantation should be performed in children with primary hyperoxaluria 1 before end-stage renal failure to normalize oxalate excretion and improve growth and bone mineralization. Received: 8 June 1998 / Accepted in revised form: 21 December 1998     

Long-term results of pre-emptive liver transplantation in primary hyperoxaluria type 1

In primary hyperoxaluria type 1 (PH 1), deficiency or mistargeting of hepatic alanine glyoxylate aminotransferase (AGT) results in over-production of oxalate and hyperoxaluria, leading to nephrocalcinosis and development of end-stage renal disease (ESRD) in the majority of patients. Renal transplantation (Tx) alone carries a high risk of disease recurrence as the metabolic defect is not cured. Therefore, combined liver/kidney Tx is recommended for patients with ESRD. An alternative approach is to cure PH 1 by pre-emptive isolated liver Tx (PLTx) before ESRD has occurred, but this approach has been carried out only occasionally and there are no uniformly accepted recommendations concerning the timing of this procedure. We report follow-up 3-5.7 yr after performing successful PLTx in four children (at the age of 3-9 yrs) with PH 1 prior to the occurrence of ESRD (glomerular filtration rate [GFR] range 27-98 mL/min/1.73 m2). There was no mortality or long-term morbidity associated with the Tx procedure. Plasma and urinary oxalate levels normalized rapidly within 4 weeks, and renal function did not deteriorate under immunosuppression, even in one patient with advanced chronic renal failure (GFR 27 mL/min/1.73 m2) who showed a stable course for more than 5.7 yrs. Although treatment must be individualized in this severe metabolic disorder, and PLTx has to be regarded as an invasive procedure, we consider that PLTx should be offered and considered early in the course of PH 1. PLTx cures the metabolic defect in PH 1 and can help to prevent, or at least delay, the progression to ESRD and systemic oxalosis.     

Stones, bones, and heredity

Genetic disorders of mineral metabolism cause urolithiasis, renal disease, and osteodystrophy. Most are rare, such that the full spectrum of clinical expression is difficult to appreciate. Diagnosis is further complicated by overlap of clinical features. Dent's disease and primary hyperoxaluria, inherited causes of calcium urolithiasis, are both associated with nephrocalcinosis and urolithiasis in early childhood and renal failure that can occur at any age but is seen more often in adulthood. Bone disease is an inconsistent feature of each. Dent's disease is caused by mutations of the CLCN-5 gene with impaired kidney-specific CLC-5 chloride channel expression in the proximal tubule, thick ascending limb of Henle, and the collecting ducts. Resulting hypercalciuria and proximal tubule dysfunction, including phosphate wasting, are primarily responsible for the clinical manifestations. Low-molecular-weight proteinuria is characteristic. Definitive diagnosis is made by DNA mutation analysis. Primary hyperoxaluria, type I, is due to mutations of the AGXT gene leading to deficient hepatic alanine–glyoxylate aminotransferase activity. Marked overproduction of oxalate by hepatic cells results in the hyperoxaluria responsible for clinical features. Definitive diagnosis is by liver biopsy with measurement of enzyme activity, with DNA mutation analysis used increasingly as mutations and their frequency are defined.

Conclusion

These disorders of calcium urolithiasis illustrate the value of molecular medicine for diagnosis and the promise it provides for innovative and more effective future treatments.     

Urinary oxalate excretion in urolithiasis and nephrocalcinosis

AIMS—To investigate urinary oxalate excretion in children with urolithiasis and/or nephrocalcinosis and to classify hyperoxaluria (HyOx).METHODS—A total of 106 patients were screened. In those in whom the oxalate: creatinine ratio was increased, 24 hour urinary oxalate excretion was measured. Liver biopsy and/or genomic analysis was performed if primary hyperoxaluria (PH) was suspected. Stool specimens were examined for Oxalobacter formigenes in HyOx not related to PH type 1 or 2 (PH1, PH2) and in controls.RESULTS—A total of 21 patients screened had HyOx (>0.5 mmol/24 h per 1.73 m²); they were classified into five groups. Eleven had PH (PH1 in nine and neither PH1 nor PH2 in two). Six had secondary HyOx: two enteric and four dietary. Four could not be classified. Seven patients had concomitant hypercalciuria. Only one of 12 patients was colonised with O formigenes compared to six of 13controls.CONCLUSIONS—HyOx is an important risk factor for urolithiasis and nephrocalcinosis in children, and can coexist with hypercalciuria. A novel type of PH is proposed. Absence of O formigenes may contribute to HyOx not related to PH1.     

Urinary oxalate excretion in urolithiasis and nephrocalcinosis.

AIMS: To investigate urinary oxalate excretion in children with urolithiasis and/or nephrocalcinosis and to classify hyperoxaluria (HyOx). METHODS: A total of 106 patients were screened. In those in whom the oxalate: creatinine ratio was increased, 24 hour urinary oxalate excretion was measured. Liver biopsy and/or genomic analysis was performed if primary hyperoxaluria (PH) was suspected. Stool specimens were examined for Oxalobacter formigenes in HyOx not related to PH type 1 or 2 (PH1, PH2) and in controls. RESULTS: A total of 21 patients screened had HyOx (>0.5 mmol/24 h per 1.73 m(2)); they were classified into five groups. Eleven had PH (PH1 in nine and neither PH1 nor PH2 in two). Six had secondary HyOx: two enteric and four dietary. Four could not be classified. Seven patients had concomitant hypercalciuria. Only one of 12 patients was colonised with O formigenes compared to six of 13 controls. CONCLUSIONS: HyOx is an important risk factor for urolithiasis and nephrocalcinosis in children, and can coexist with hypercalciuria. A novel type of PH is proposed. Absence of O formigenes may contribute to HyOx not related to PH1.     

儿童原发性1型高草酸尿症1例并文献复习

目的 总结儿童原发性1型高草酸尿症 (PH 1)临床资料,提高对该病的认识。方法 采集1例PH 1患儿的临床特点、影像学表现,肾结石分析信息;进行家系调查;对该家系相关成员进行AGXT基因外显子及附近调控区域直接测序,分析突变位点;文献综述。结果 女童,3岁时起病,首发症状为肉眼血尿,继腰、背部疼痛,体外震波碎石、排石治疗后结石复发,7年内进展为终末期肾病。腹部B超、X线平片和CT均提示多发双肾脏和输尿管结石。肾结石成份为单水草酸钙。未发现患儿家族有相同疾病的患者。AGXT基因分析发现,患儿存在c.242C>A（p.Ser81X）和c.823_824dupAG（p.Ser275delinsArgAlafs）杂合突变,其父亲携带c.823_824dupAG杂合突变,其母亲携带c.242C>A杂合突变。患儿为AGXT基因复合杂合突变,其中c.242C>A无义突变为首次报道。结论 PH 1为罕见遗传性疾病。经影像学证实为多发和复发性双肾结石,排除其他原因所致,应该考虑原发性高草酸尿症,肾结石成份和AGXT基因分析是PH 1诊断的重要手段,尤其AGXT基因分析在某些情况下可以替代肝穿刺成为PH 1确诊的无创检查;PH 1早期诊断和干预将会延缓肾功能恶化,改善预后。     

Renal calculi in children

An increasing number of paediatric patients of all ages with renal calculi are being seen in outpatient clinics worldwide. This is attributed to changes in environmental factors like diet, fluid intake and obesity. In children however, genetic and/or metabolic disorders are still the main reason for kidney stones. Next to hypercalciuria, which is generally considered to be the most frequent risk factor, other lithogenic or stone-inhibitory disorders like hypocitraturia or hyperoxaluria and a variety of renal tubular diseases have to be evaluated by urine and/or blood analysis. Non-specific symptoms like growth retardation, intestinal malabsorption or bone demineralization are to be considered not only to avoid further complications, but for diagnostic purposes. In preterm infants a high incidence of nephrocalcinosis is observed. These infants often have a combination of immature kidney function or medication that leads to relative hypocitraturia. Concise evaluation to diagnose the underlying patho-mechanism as early as possible is mandatory in all paediatric patients. In more than three-quarters of children a metabolic basis of urolithiasis/nephrocalcinosis will be found. Early treatment by reducing urinary saturation index by increasing fluid intake, by providing crystallization inhibitors, but also by disease specific medication prevents recurrent kidney stones and/or progressive nephrocalcinosis and therefore deterioration of renal function.     

Combined split liver and kidney transplantation in a three‐year‐old child with primary hyperoxaluria type 1 and complete thrombosis of the inferior vena cava

Khan Z, Sciveres M, Salis P, Minervini M, Maggione G, Cintorino D, Riva S, Gridelli B, Emma F, Spada M. Combined split liver and kidney transplantation in a three‐year‐old child with primary hyperoxaluria type 1 and complete thrombosis of the inferior vena cava.
Pediatr Transplantation 2011: 15: E64–E70. © 2009 John Wiley & Sons A/S. Abstract: PH1 is an inborn error of the metabolism in which a functional deficiency of the liver‐specific peroxisomal enzyme, AGT, causes hyperoxaluria and hyperglycolic aciduria. Infantile PH1 is the most aggressive form of this disease, leading to early nephrocalcinosis, systemic oxalosis, and end‐stage renal failure. Infantile PH1 is rapidly fatal in children unless timely liver‐kidney transplantation is performed to correct both the hepatic enzyme defect and the renal end‐organ damage. The surgical procedure can be further complicated in infants and young children, who are at higher risk for vascular anomalies, such as IVC thrombosis. Although recently a limited number of children with IVC thrombosis have underwent successful kidney transplantation, successful multi‐organ transplantation in a child with complete IVC thrombosis is quite rare. We report here the interesting and technically difficult case of a three‐yr‐old girl with a complete thrombosis of the IVC, who was the recipient of combined split liver and kidney transplantation for infantile PH1. Although initial delayed renal graft function with mild‐to‐moderate acute rejection was observed, the patient rapidly regained renal function after steroid boluses, and was soon hemodialysis‐independent, with good diuresis. Serum and plasma oxalate levels progressively decreased; although, to date they are still above normal. Hepatic and renal function indices were at, or approaching, normal values when the patient was discharged 15‐wk post‐transplant, and the patient continues to do well, with close and frequent follow‐up. This is the first report of a successful double‐organ transplant in a pediatric patient presenting with infantile PH1 complicated by complete IVC thrombosis.     

Primary hyperoxaluria type 1 with a novel mutation

Primary hyperoxaluria type 1 [PH1] is an autosomal recessive disorder caused by a deficiency of alanine-glyoxylate aminotransferase AGT, which is encoded by the AGXT gene. We report an Indian family with two affected siblings having a novel mutation in the AGXT gene inherited from the parents. The index case progressed to end stage renal disease at 5 months of age. His 4 month old sibling is presently under follow up with preserved renal function.     

Stones, bones, and heredity

Genetic disorders of mineral metabolism cause urolithiasis, renal disease, and osteodystrophy. Most are rare, such that the full spectrum of clinical expression is difficult to appreciate. Diagnosis is further complicated by overlap of clinical features. Dent's disease and primary hyperoxaluria, inherited causes of calcium urolithiasis, are both associated with nephrocalcinosis and urolithiasis in early childhood and renal failure that can occur at any age but is seen more often in adulthood. Bone disease is an inconsistent feature of each. Dent's disease is caused by mutations of the CLCN-5 gene with impaired kidney-specific CLC-5 chloride channel expression in the proximal tubule, thick ascending limb of Henle, and the collecting ducts. Resulting hypercalciuria and proximal tubule dysfunction, including phosphate wasting, are primarily responsible for the clinical manifestations. Low-molecular-weight proteinuria is characteristic. Definitive diagnosis is made by DNA mutation analysis. Primary hyperoxaluria, type I, is due to mutations of the AGXT gene leading to deficient hepatic alanine-glyoxylate aminotransferase activity. Marked overproduction of oxalate by hepatic cells results in the hyperoxaluria responsible for clinical features. Definitive diagnosis is by liver biopsy with measurement of enzyme activity, with DNA mutation analysis used increasingly as mutations and their frequency are defined.These disorders of calcium urolithiasis illustrate the value of molecular medicine for diagnosis and the promise it provides for innovative and more effective future treatments.     

6月龄女婴尿量减少伴急性肾功能异常

患儿,女,6月龄,急性起病,因尿量减少、肾功能异常入院。辅助检查提示严重代谢性酸中毒,血肌酐和尿素氮明显增高。予限制液体、纠正酸中毒、连续床旁血液净化等治疗10 d,患儿仍持续无尿,放弃治疗后死亡。患儿姐姐于6月龄死于急性肾功能衰竭。患儿经基因检测证实为丙氨酸乙醛酸氨基转移酶(AGT)编码基因AGXT突变引起的原发性高草酸尿症1型(PH1),其父母为杂合突变携带者。PH1是一种临床罕见疾病,对于肾功能显著异常,或伴反复发作肾结石,以及有类似家族史的患者,应考虑到PH1的可能,AGXT基因分析是PH1诊断的重要手段。     

Oxalosis in infancy.

We describe 3 infants with nephrocalcinosis and terminal renal failure. In all 3 there was widespread oxalate deposition: biochemical evidence of primary hyperoxaluria was sought but the presence of severe renal failure and the lack of established normal values for urinary and plasma oxalate and glycollate in infants made this diagnosis difficult to establish.     

Combined liver‐kidney transplantation for primary hyperoxaluria type I in children: Single Center Experience

Primary hyperoxalurias are rare inborn errors of metabolism with deficiency of hepatic enzymes that lead to excessive urinary oxalate excretion and overproduction of oxalate which is deposited in various organs. Hyperoxaluria results in serious morbid‐ity, end stage kidney disease (ESKD), and mortality if left untreated. Combined liver kidney transplantation (CLKT) is recognized as a management of ESKD for children with hyperoxaluria type 1 (PH1). This study aimed to report outcome of CLKT in a pediatric cohort of PH1 patients, through retrospective analysis of data of 8 children (2 girls and 6 boys) who presented by PH1 to Wadi El Nil Pediatric Living Related Liver Transplant Unit during 2001‐2017. Mean age at transplant was 8.2 ± 4 years. Only three of the children underwent confirmatory genotyping. Three patients died prior to surgery on waiting list. The first attempt at CLKT was consecutive, and despite initial successful liver transplant, the girl died of biliary peritonitis prior to scheduled renal transplant. Of the four who underwent simultaneous CLKT, only two survived and are well, one with insignificant complications, and other suffered from abdominal Burkitt lymphoma managed by excision and resection anastomosis, four cycles of rituximab, cyclophosphamide, vincristine, and prednisone. The other two died, one due to uncontrollable bleeding within 36 hours of procedure, while the other died awaiting renal transplant after loss of renal graft to recurrent renal oxalosis 6 months post‐transplant. PH1 with ESKD is a rare disease; simultaneous CLKT offers good quality of life for afflicted children. Graft shortage and renal graft loss to oxalosis challenge the outcome.     

An institutional experience of pre‐emptive liver transplantation for pediatric primary hyperoxaluria type 1

Primary hyperoxaluria type 1 (PH1) is an inherited metabolic disease that culminates in ESRF. Pre‐emptive liver transplantation (pLTx) treats the metabolic defect and avoids the need for kidney transplantation (KTx). An institutional experience of pediatric PH1 LTx is reported and compared to the literature. Between 2004 and 2015, eight children underwent pLTx for PH1. Three underwent pLTx with a median GFR of 40 (30–46) mL/min/1.73 m² and five underwent sequential combined liver‐kidney transplantation (cLKTx); all were on RRT at the time of cLKTx. In one case of pLTx, KTx was required eight and a half yr later. pLTx was performed in older (median 8 vs. 2 yr) and larger children (median 27 vs. 7.75 kg) that had a milder PH1 phenotype. In pediatric PH1, pLTx, ideally, should be performed before renal and extrarenal systemic oxalosis complications have occurred, and pLTx can be used “early” or “late.” Early is when renal function is preserved with the aim to avoid renal replacement. However, in late (GFR < 30 mL/min/1.73 m²), the aim is to stabilize renal function and delay the need for KTx. Ultimately, transplant strategy depends on PH1 phenotype, disease stage, child size, and organ availability.     

Clinical characteristics and metabolic abnormalities in preschool-age children with urolithiasis in southeast Anatolia

ObjectiveData on urolithiasis in preschool-age children are limited. The aim of this study was to investigate the metabolic etiology and clinical findings of preschool-age children with urolithiasis.MethodsThe medical records of 143 preschool-age children (81 boys, 62 girls, aged 2–6 years) with urolithiasis were retrospectively analyzed. Results of physical examination, serum biochemistry, and urine metabolic evaluation (including urinary citrate, oxalate, calcium, uric acid, cystine, and magnesium) were recorded.ResultsThe mean age at diagnosis was 3.7 ± 1.3 years. A family history of stone disease was found in 79.7% of patients, and 37% of parents had consanguineous marriages. The most common presenting symptoms were hematuria (33%) and urinary tract infection (UTI; 29%). Metabolic abnormalities were found in 119 (83.2%) patients, including hyperuricosuria in 24.5%, hypocitraturia in 23.8%, hyperoxaluria in 21.7%, hypercalciuria in 21.0%, cystinuria in 7.7%, and hypomagnesuria in 1.4%. Multiple metabolic abnormalities were found in 24 (16.8%) patients. Results of 28 stone analyses revealed calcium oxalate or phosphate, cystine, and uric acid in 15, nine, and four of the patients, respectively. ^99mTechnetium–dimercaptosuccinic acid renal scintigraphy revealed that 27.8% of the children with UTI had renal parenchymal scarring, with only four of them having vesicoureteral reflux.ConclusionThe most frequent metabolic abnormalities in preschool-age children with urolithiasis were hyperuricosuria and hypocitraturia. A comprehensive investigation of stone disease in children presenting with hematuria and UTI is important to prevent the development of renal parenchymal scarring.     

Nephrocalcinosis in full-term infants receiving furosemide treatment for congestive heart failure: a study of the incidence and 2-year follow up

In order to study the incidence and course of nephrocalcinosis in full-term infants with congestive heart failure receiving long-term furosemide treatment, 36 such infants (median age 2.9 months, range 1.2–8.0) and 36 full-term control infants not receiving any diuretics (median age 3.4 months, range 1.1–8.4) were studied by renal ultrasonography and random urine calcium variables. The infants with nephrocalcinosis were followed at 3–6 month intervals up to 2 years of age, or until ultrasonic resolution. Nephrocalcinosis was found in 5 out of the 36 (14%) treated infants, but in none of the controls (P = 0.03). The dose of furosemide was higher in the infants with nephrocalcinosis than in those without (1.9 ± 0.6 vs. 1.3 ± 0.4 mg/kg per day; P = 0.01). The urinary calcium concentration was higher in the infants receiving furosemide than in& controls and a similar trend was observed in the urinary calcium/creatinine ratio, but& these variables did not differ between the study infants with and without nephrocalcinosis. Ultrasonic resolution of nephrocalcinosis was observed in 3 of the 5& infants at 12 months, but in the other 2 the condition still persisted at 24 months. Conclusions Long-term furosemide treatment in full-term infants with congestive heart failure entails a considerable risk of developing nephrocalcinosis. Renal ultrasonography is warranted in these patients within a few months after initiation of the treatment and in the case of nephrocalcinosis alteration of the diuretic regimen is to be considered. Received: 8 September 1998 / Accepted in revised form: 12 January 1999     

Successful outcome after early combined liver and en bloc-kidney transplant in an infant with primary hyperoxaluria type 1: A case report

Abstract:  PH1 is a metabolic disorder characterized by urolithiasis and the accumulation of oxalate crystals in the kidneys and other organs. Although patients often first present with renal failure, PH1 results from a deficiency of the hepatic peroxisomal enzyme AGT. Ultimately only liver transplantation will cure the underlying metabolic defect. Herein, we report the case of a three-month-old male infant diagnosed with PH and treated using a combined liver and en bloc- kidney transplant from a single donor. At the time of transplant, the patient was 11 months old and weighed 7.9 kg. He received a full size liver graft and en bloc kidneys from a two-yr-old donor. At 36 months post-transplant, the patient is steadily growing with normal renal and hepatic function. This is one of the first reports of successful liver and en bloc -kidney transplantation with abdominal compartment expansion by PTFE for the infantile form of PH1 in a high risk child before one yr of age. Prompt diagnosis and early referral to a specialized center for liver and kidney replacement offer the best chance for survival for infants with this otherwise fatal disease.     

Bilateral urinary calculi after treatment with a silicate-containing milk thickener

Nephrocalcinosis and/or urinary calculi are rare in infants. Furosemide treatment during the neonatal period, vitamin D intoxication, hereditary diseases such as hyperoxaluria or distal tubular acidosis are among the most common aetiologies. We report the case of a 6-month-old boy with an extra-hepatic biliary duct atresia treated by the Kasai procedure and a gastro-oesophageal reflux treated with a silicate containing milk thickener (Gelopectose, 5.5% colloidal silicate) since the neonatal period. He did not present any other endogenous risk factor for urinary stone formation (normal urinary calcium/creatinine ratio; normal urinary magnesium excretion). The nephrolithiasis was discovered as the boy presented painful episodes of macroscopic haematuria. Ultrasound examination revealed bilateral nephrocalcinosis and multiple bilateral calculi without infection or urinary obstruction. Infrared spectroscopy revealed silicate as the major component suggesting silicate absorption to be responsible for the described symptoms. After replacement of the silicate-containing agent by a silicate-free milk thickener, the lesions were completely reversible as confirmed by repeated renal ultrasound examinations over a 2-month period. Conclusion:silicate-containing milk thickeners can be responsible for urinary calculi and/or nephrocalcinosis.     

Nephrocalcinosis due to primary hyperoxaluria: case report from Saudi Arabia

Two Arab siblings with nephrocalcinosis and renal failure secondary to primary hyperoxaluria are presented. Percutaneous renal biopsies obtained from both siblings showed marked oxalate deposition in the renal medulla. Primary hyperoxaluria should be considered in the differential diagnosis of renal failure in infancy and early childhood especially when evidence of obstructive uropathy is lacking.