Evaluation of renal tubular acidosis

Renal tubular acidoses (RTA) comprises of a group of disorders characterized by a low capacity for net acid excretion and persistent hyperchloremic, metabolic acidosis. The RTAs are classified into chiefly three types (types 1,2 and 4) based on clinical and laboratory characteristics. Correct diagnosis involves careful evaluation, including exclusion of other entities causing acidosis. A variety of tests are required to be administered in a stepwise fashion for the diagnosis and characterization of RTA.     

Renal tubular dysfunction in methylmalonic acidaemia

Renal tubular function was assessed in seven patients with methylmalonic acidaemia not responsive to vitamin B₁₂. Five patients failed to concentrate their urine normally and in these patients the glomerular filtration rate was also reduced. Fractional excretion of sodium was increased in four patients, fractional excretion of potassium in one patient and in three there was a decreased tubular reabsorption of phosphate. Although possibly representing primary tubular damage these findings were thought to be consistent with adaptive changes secondary to the reduced glomerular filtration rate. Two patients had evidence of a defect of urinary acidification and several had a degree of hyporeninaemic hypoaldosteronism suggesting type 4 renal tubular acidosis. In one patient with a mild variant no renal disease was detected. Decreased renal function and tubular abnormalities were common in patients with methylmalonic acidaemia. It is likely that they are linked and essentially secondary to the tubulo-interstitial nephritis that is histologically demonstrable on renal biopsy. The failure of urinary concentrating ability and the disturbed urine acidification will contribute to the metabolic derangement during episodes of decompensation.     

Renal tubular acidosis — a case report

A case of primary distal type of renal tubular acidosis (RTA) diagnosed at the age of 14 days in a neonatal nursery is reported. The course of illness and management upto the age of four years is described.     

Growth failure associated with medullary sponge kidney,due to incomplete renal tubular acidosis type 1

A girl, 12 years of age, was referred for short stature. Clinical examination and laboratory investigations currently performed in a case of growth failure gave normal results. Renal echography revealed a hyper-echogenic renal medulla. An excretory urogram showed medullary sponge kidney with bilateral renal calculi. An ammonium chloride loading test revealed a defect in acid excretion and led to the diagnosis of incomplete renal tubular acidosis. Treatment with oral bicarbonate was associated with an increase in growth velocity.     

Hashimoto thyroiditis,distal renal tubular acidosis,pernicious anaemia and encephalopathy: A rare combination of auto-immune disorders in a 12-year-old girl

A case of a 12-year-old girl with a multiple auto-immune disorder is reported. She showed Hashimoto thyroiditis which subsequently developed to hashitoxicosis and distal renal tubular acidosis at 5 years of age, pernicious anaemia at the age of 9 and severe encephalopathy at the age of 12. Laboratory studies revealed very high titres of anti-microsomal and anti-thyroglobulin antibodies and positive gastric parietal cell antibody. As to the encephalopathy, positive oligoclonal IgG bands and high values of IgG index and IgG synthesis ratio in CSF were observed with aggravation of her neurological symptoms. High-dose steroid therapy was effective toward the encephalopathy. Paediatricians should pay careful attention to patients with Hashimoto thyroiditis for association with other auto-immune disorders.     

以肾小管酸中毒为首发表现的儿童恶性淋巴瘤

原发性肾淋巴瘤是原发于淋巴结以外的一种恶性淋巴瘤,罕见于儿童。该文报道2例以肾小管酸中毒为首发表现,以肾组织穿刺病理确诊的儿童原发性肾淋巴瘤。2例皆以“多饮、多尿、乏力、呕吐、贫血”为主要症状,双肾肿大,伴低钾、低钙、低磷,代谢性酸中毒等。1例放弃治疗,另外1例经泼尼松、长春新碱、阿糖胞苷＋L-天冬氨酰胺酶(PVA+L-ASP)方案化疗,联合氨甲喋呤、地塞米松、阿糖胞苷鞘内注射、纠酸、补钾、输血及对症支持治疗后,多饮多尿症状缓解,内环境稳定, 复查肾B超无异常发现。一旦怀疑该型恶性淋巴瘤,应尽快肾组织穿刺病理确诊,早期采取综合治疗,包括手术、化疗与放疗、支持疗法等。     

遗传性远端肾小管酸中毒的临床特点和SLC4A1基因突变分析

目的研究两个原发性远端肾小管酸中毒(d RTA)家系的临床特征和致病基因SLC4A1突变情况。方法通过家系调查、病史采集和生化指标检测,分析d RTA临床表型和遗传特点。通过直接测序法检测SLC4AI基因突变。结果两个家系共有3例患者(其中两例为母子)确诊为d RTA,均有显著的临床特征,包括身材矮小、代谢性酸中毒、碱性尿、低钾血症和肾脏钙盐沉积。SLC4A1基因分析证实3例患者均存在致病性错义突变R589H(c.1766GA)。家系1的患儿为SCL4A1的新生突变,家系2患儿的SLC4A1基因突变遗传自其母,符合常染色体显性遗传特点。结论本研究首次在国内报道遗传性d RTA家系中SLC4A1基因R589H突变。对疑似遗传性d RTA患者进行基因检测可提高早期诊治率。     

Nephrocalcinosis in children: a retrospective multi-centre study

Aim:  To review the data of children with NC and to analyse aetiology, clinical manifestations, growth and renal function at presentation; to relate growth and renal function to changes in NC in patients with a follow-up of at least 12 months.
Methods:  Data of 41 children from four institutions were gathered retrospectively.
Results:  Presenting symptoms were failure to thrive in the first year of life (41%), urinary tract infections, bladder voiding dysfunction or abdominal pain (17%) and psychomotor delay (10%). In 24% of cases NC was detected incidentally. Glomerular function at diagnosis was normal in 83% of children. During a median follow-up of 4 yrs and 5 months in 28 patients, growth standard deviation score improved from a median of −2.2 to −1.0 and glomerular function remained stable in 89% of patients, in spite of worsening of the degree of NC in 62% of cases. The most frequent causes of NC were hereditary tubulopathies and vitamin D intoxication.
Conclusion:  Our results show that the treatment of the underlying conditions is associated with catch-up growth and stabilization of glomerular function in many children, but not with the reduction in the degree of NC in the majority of cases. We believe that early recognition of conditions leading to NC is clinically useful and suggest a diagnostic flowchart, which may be helpful in the approach to NC.     

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??Objective??To analyze the clinical features and the results of genetic diagnosis in children with hypokalemic renal tubular diseases. Methods??The clinical data of 38 patients with hypokalemic renal tubular diseases were analyzed retrospectively??who were treated in Children’s Hospital Affiliated to Shanghai Jiao Tong University from Jan. 2010 to Jan. 2016. Results??Totally 38 patients with hypokalemic renal tubular diseases were enrolled in this study. There were 18 cases of renal tubular acidosis??RTA?? including 17 cases of type??RTA and 1 case of type?? RTA. There were 11 cases of Bartter syndrome??5 cases of Gitelman syndrome and 4 cases of Fanconi syndrome. The common clinical manifestations of hypokalemic renal tubular diseases included myasthenia??nausea??vomiting??polydipsia??polyurine and growth retardation. One case of Fanconi syndrome progressed to chronic Kidney disease??phase ????while the other
children had normal renal function. Glomerular proteinuria was found in 1??1 and 3 children with Bartter syndrome??Gitelman syndrome and Fanconi syndrome??respectively. Additionally??1 case with Fanconi syndrome has tubular proteinuria. However??urinary trace proteins associated with glomerular and tubular injury commonly elevated in these hypokalemic renal tubular diseases. Genetic analysis showed a new potential heterozygous mutations of ATPV0A4 in type??RTA and three heterozygous mutations of SLC12A3 in Gitelman syndrome. Conclusion??The clinical symptoms vary in patients and are featured mainly by myasthenia??nausea??vomiting??polydipsia??polyurine and growth retardation. Glomerular and tubular injuries are commonly found in hypokalemic renal tubular diseases. Moreover??genetic diagnosis may be helpful in diagnosis??treatment and genetic counseling.     

90例肾小管性酸中毒临床分析

为提高对肾小管性酸中毒(RTA)的临床认识，减少误诊和漏诊，回顾性分析了90例RTA的病因、临床症状、体征和实验室检查。结果发现原发性RTA占65．6％，继发性RTA占34．4％，临床初次误诊高达54．4％。RTA临床表现无特异性，生长发育落后最常见，占72．2％，其中6例合并生长激素缺乏(GHD)，其他表现有纳差、呕吐、下肢疼痛、骨骼畸形等。临床分型中I型最常见，占82％，Ⅱ、Ⅲ型各占6．7％，Ⅳ型为4．6％。检测尿酸化功能66例，其中I型达印例，52例明显下降，8例轻度下降者经NH4Cl负荷试验确诊。提示RTA在儿童期并非罕见，临床误诊率高，需提高警惕；多种疾病可继发RTA，临床上应全面判断；尿酸化功能测定是RTA诊断的可靠指标。     

Nephrocalcinosis in glucose-galactose malabsorption: nephrocalcinosis and proximal tubular dysfunction in a young infant with a novel mutation of SGLT1

We report an association of proximal renal tubular dysfunction in a 50-day-old girl with glucose-galactose malabsorption who was found to have nephrocalcinosis, but no sign of nephrolithiasis. A novel homozygous nonsense mutation at 267Arg →stop (CGA→TGA) in the Na⁺-dependent glucose transporter (SGLT1) was found in loop 5 connecting transmembrane segments 6 and 7, indicating the complete loss of glucose transport activity. This case indicates that hypercalcaemia, nephrocalcinosis and proximal tubular dysfunction may be seen in association with glucose-galactose malabsorption and that most of these abnormalities improve with a glucose-galactose-free diet.     

Medullary sponge kidney associated with distal renal tubular acidosis in a 5-year-old girl

Introduction Medullary sponge kidney (MSK) is characterized by cystic dilatation of the inner medullary collecting ducts, which causes the kidneys to resemble a sponge.Case report Although distal renal tubular acidosis (dRTA) is commonly observed in patients with MSK, we report a 5-year-old girl with MSK who had features of both dRTA (nephrocalcinosis, hypercalciuria, hypocitraturia) and proximal tubular dysfunction (hyperuricosuria, impaired tubular phosphate reabsorption and proteinuria).Discussion Metabolic acidosis, hypercalciuria, hypocitraturia, tubular phosphate reabsorption and growth retardation in the patient improved with alkali therapy.     

Inherited renal tubular dysgenesis: the first patients surviving the neonatal period

Renal tubular dysgenesis (RTD) is a clinical disorder either acquired during fetal development or inherited as an autosomal recessive condition. Inherited RTD is caused by mutations in the genes encoding the components of the renin-angiotensin system angiotensinogen, renin, angiotensin-converting enzyme and angiotensin II receptor type 1. Inherited RTD is characterized by early onset oligohydramnios, skull ossification defects, preterm birth and neonatal pulmonary and renal failure. The histological hallmark is the absence or poor development of proximal tubules. So far, all patients died either in utero or shortly after birth. We report the first patients with inherited RTD surviving the neonatal period and still being alive. Genetic and functional analysis of the renin-angiotensin system contributes to the diagnosis of RTD. In conclusion, the clinical diagnosis of inherited RTD is easily missed after birth without renal biopsy or information on affected family members. Genetic and functional analysis of the renin-angiotensin system contributes to correct diagnosis.     

Genetic and long-term data on a patient with permanent isolated proximal renal tubular acidosis

A 12-year-old girl presented with permanent isolated proximal renal tubular acidosis (pRTA), glaucoma, band keratopathy, mild cataract and short stature. Severe metabolic acidosis was caused by the impairment of bicarbonate reabsorption in the proximal tubules and alkali therapy improved her acidaemia. A homozygous G to A transition at nucleotide 1,678 in the basolateral kidney type Na⁺/HCO₃ ⁻ (kNBC) co-transporter gene SLC4A4, which is critical in HCO₃ ⁻ resorption in renal proximal tubules, was identified. Her height and height velocity (HV) were very low (−4.0 SD and −4.4 SD, respectively) before alkali treatment, but both improved after initiating alkali therapy at the age of 2 years and 3 months. The patient's body height and HV were 131.5 cm (−2.7 SD) and 4.0 cm (−2.0 SD), respectively at the age of 12 years. Conclusion This case demonstrates that early administration of alkali therapy and sustained correction of acidosis, even if inadequate to correct the metabolic acidosis, can markedly improves growth in permanent isolated proximal renal tubular acidosis. Received: 3 April 2000 / Accepted: 5 July 2000