Incomplete Renal Tubular Acidosis Research Articles

Phytate Effects on Incomplete Distal Renal Tubular Acidosis.

Background: Adults who have incomplete distal renal tubular acidosis (dRTA) may present with recurrent urolithiasis due to metabolic acidosis, leading to bone resorption, which in turn causes hypercalciuria and urine alkalinization (pH > 6.0). Oral potassium citrate is the most commonly used treatment for dRTA, but some patients cannot tolerate this treatment. The objective of this single-arm study was to evaluate the effect of phytate, an inhibitor of bone resorption, on calciuria of patients with incomplete dRTA. Methods: The calciuria levels of 16 patients who had incomplete dRTA with urolithiasis and could not tolerate potassium citrate treatment were recorded before (baseline) and after 6 months of treatment with oral calcium magnesium phytate (380 mg every 12 h). There were no dietary modifications or other treatments. Results: The baseline calciuria was 317 ± 81 mg/24 h and the level after 6 months was 221 ± 38 mg/24 h (p < 0.005). Conclusions: Our results suggest that calcium magnesium phytate should be considered as an alternative or adjunctive treatment for hypercalciuria in patients with incomplete dRTA.

Evaluation of urinary acidification in children: Clinical utility.

The kidney plays a fundamental role in acid-base homeostasis by reabsorbing the filtered bicarbonate and by generating new bicarbonate, to replace that consumed in the buffering of non-volatile acids, a process that leads to the acidification of urine and the excretion of ammonium (NH4 +). Therefore, urine pH (UpH) and urinary NH4 + (UNH4 +) are valuable parameters to assess urinary acidification. The adaptation of automated plasma NH4 + quantification methods to measure UNH4 + has proven to be an accurate and feasible technique, with diverse potential indications in clinical practice. Recently, reference values for spot urine NH4 +/creatinine ratio in children have been published. UpH and UNH4 +, aside from their classical application in the study of metabolic acidosis, have shown to be useful in the identification of incomplete distal renal tubular acidosis (dRTA), an acidification disorder, without overt metabolic acidosis, extensively described in adults, and barely known in children, in whom it has been found to be associated to hypocitraturia, congenital kidney abnormalities and growth impairment. In addition, a low UNH4 + in chronic kidney disease (CKD) is a risk factor for glomerular filtration decay and mortality in adults, even in the absence of overt metabolic acidosis. We here emphasize on the need of measuring UpH and UNH4 + in pediatric population, establishing reference values, as well as exploring their application in metabolic acidosis, CKD and disorders associated with incomplete dRTA, including growth retardation of unknown cause.

MO097: Idiopathic Hypercalciuria: Calciuria and Citraturia Evolution. A 20-year Longitudinal Study

Abstract BACKGROUND AND AIMS Reduction and normalization of calciuria in children with idiopathic hypercalciuria (IH) was published by Aladjem et al. (1996). The association between IH and hypocitraturia was described in two Brazilian studies; however, further studies are needed to determinate the caracteristics of its relation. We studied calcium and citrate urinary excretion in children diagnosed with IH and followed up until adulthood. METHOD: A total of 34 patients (12 M and 22 F) were studied. IH diagnosis was performed at the age of 7.9 ± 3 years (range: 1–14). Hypercalciuria was defined as urinary calcium excretion of &amp;gt;4 mg/kg/day in two successive samples. Calciuria and citraturia were collected in the first urine sample of the day at the same time as bone densitometry was performed. Three determinations were made: the first (D1) at age 10.5 ± 2.7 years (range: 6.5–16.8), the second (D2) at age 14.5 ± 2.7 years (range: 9.9–19.5) and the third (D3) at age 28.2 ± 2.8 years (range: 24.1–35.9). RESULTS: Calcium/creatinine ratio (P = 0.005) and citrate/creatinine ratio (P &amp;lt; 0.001) reduction during follow up was observed. In addition, we observed an increase in the calcium/citrate ratio (P = 0.008). Patients with a calcium/creatinine ratio higher than 0.20 mg/mg decreased from 100% at diagnosis to 52.9% (18/34) on D1 and to 26.5% (9/34) on D2 and 23.5% (8/34) in adulthood (D3). Lithogenetic risk decreased from diagnosis (15/28; 53.6%) to D1 (13/32; 40.6%) and D2 (8/28; 28.6%) but increased in adulthood (21/30; 70%). CONCLUSION It is difficult to explain why some IH patients present a decrease in both calcium and citrate excretion in adolescence and early adulthood, which has an impact on lithogenic risk. The interpretation of these results is complex. Bone is the largest reservoir of alkaline salts in the body. Our hypothesis is that late hypocitraturia observed in patients with IH would be an indirect sign of high functional osteoblastic activity. Increased proximal tubular citrate reabsorption would denote an increased bicarbonate production, which is necessary as osteoblastic activity increases, thus requiring increased inputs of alkali, calcium (normalized calciuria) and phosphate. Another option could be the development of incomplete distal renal tubular acidosis.

Prospective long-term evaluation of incomplete distal renal tubular acidosis in idiopathic calcium nephrolithiasis diagnosed by low-dose NH4CL loading – gender prevalences and impact of alkali treatment

PurposeProspective evaluation of the prevalence of incomplete distal renal tubular acidosis (idRTA) in idiopathic calcium stone formers (ICSF) diagnosed by half-dose ammonium chloride loading (NH4Cl, 0.05 g/kg body weight/day) and impact of alkali treatment of idRTA.MethodsEvaluation of 386 consecutive idiopathic calcium stone formers (ICSF) (280 males, 106 females) for idRTA. If screening fasting urine pH was > 5.80, 1-day NH4Cl loading was performed without severe adverse effects. Normally, urine pH falls below 5.45.ResultsSixty-four idiopathic calcium stone formers exhibited idRTA, one complete dRTA. Prevalence was higher in women (25.4%) than in men (13.6%). Thus, for more equilibrated comparisons, we formed pairs of 62 idiopathic calcium stone formers (ICSF) with and 62 without idRTA, matched for gender, age, BMI and serum creatinine. Idiopathic calcium stone formers with idRTA more often had hypercalciuria (p < 0.025) and urine citrate < 2 mmol/d (p < 0.05), formed calcium phosphate stones more frequently, exhibited higher numbers of stones/year (1.4 ± 1.5 vs. 0.9 ± 0.8, p = 0.034) and 2.5 times more intrarenal calcifications (4.6 ± 5.9 vs. 1.8 ± 3.6, p = 0.002). All idiopathic calcium stone formers with idRTA were recommended chronic alkali therapy. After 4–15 years of follow-up, stone events /years follow-up (stone passage or urologic intervention) were higher in patients non-adherent to alkali therapy (0.61 ± 0.92) than in patients adherent to treatment (0.11 ± 0.21, p = 0.006).Conclusion Incomplete distal renal tubular acidosis is 1.8-fold more prevalent among female idiopathic calcium stone formers, predicts more stone recurrences, predisposes to calcium phosphate stones and is associated with 2.5 times more intrarenal calcifications vs. non-idRTA patients. Chronic alkali treatment reduces clinical stone recurrences by 5.5 times.Graphical abstract

Results of a Gene Panel Approach in a Cohort of Patients with Incomplete Distal Renal Tubular Acidosis and Nephrolithiasis

Background: Distal renal tubular acidosis (dRTA) is characterized by an impairment of urinary acidification resulting in metabolic acidosis, hypokalemia, and inappropriately elevated urine pH. If not treated, this chronic condition eventually leads to nephrocalcinosis, nephrolithiasis, impaired renal function, and bone demineralization. dRTA is a well-defined entity that can be diagnosed by genetic testing of 5 genes known to be disease-causative. Incomplete dRTA (idRTA) is defined as impaired urinary acidification that does not lead to overt metabolic acidosis and therefore can be diagnosed if patients fail to adequately acidify urine after an ammonium chloride (NH₄Cl) challenge or furosemide and fludrocortisone test. It is still uncertain whether idRTA represents a distinct entity or is part of the dRTA spectrum and whether it is caused by mutations in the same genes of overt dRTA. Methods: In this cross-sectional study, we investigated a group of 22 stone formers whose clinical features were suspicious of idRTA. They underwent an NH₄Cl challenge and were found to have impaired urinary acidification ability. These patients were then analyzed by genetic testing with sequencing of 5 genes: SLC4A1, ATP6V1B1, ATP6V0A4, FOXI1, and WDR72. Results: Two unrelated individuals were found to have two different variants in SLC4A1 that had never been described before. Conclusions: Our results suggest the involvement of other genes or nongenetic tubular dysfunction in the pathogenesis of idRTA in stone formers. However, genetic testing may represent a cost-effective tool to recognize, treat, and prevent complications in these patients.

Maternally inherited diabetes and deafness (MIDD) syndrome with m.3243A&gt;G mutation associated with renal failure — a case report

Maternally-inherited diabetes with deafness (MIDD) is a rare form of monogenic diabetes that results, in most cases, from an A-to-G transition at position 3243 of mitochondrial DNA (m.3243A>G). The clinical presentation of m.3243A>G mutation is variable, ranging from mild to severe phenotypes. Diabetes is often accompanied by sensorineural deafness, cardiomyopathy, neuromuscular, psychiatric disorders, macular dystrophy and renal failure (kidney manifestations in adults presenting with this mutation remain poorly defined). The study presents a case of a 40-years-old woman with a history of bilateral sensorineural deafness, renal failure and diabetes that was diagnosed due to increasing muscle weakness during exercise. MIDD was diagnosed based on the clinical picture and the results of laboratory studies including genetic testing. As far as we know, glomerulopathy with incomplete distal renal tubular acidosis has never been described before as a cause of renal failure in MIDD patients.

P0058THE ROLE OF GENETICS IN INCOMPLETE DISTAL RENAL TUBULAR ACIDOSIS IN NEPHROLITHIASIS

Abstract Background and Aims Distal renal tubular acidosis (dRTA) is characterized by an impairment of urinary acidification resulting in a hyperchloremic non-anion gap metabolic acidosis, hypokalemia and inappropriately elevated urine pH. If not treated, this chronic condition eventually leads to nephrocalcinosis and recurrent nephrolithiasis, impaired renal function and bone demineralization due to reabsorption of bicarbonate and phosphate complexed with calcium from the bone as a buffer for metabolic acidosis. Distal RTA is therefore a well-defined entity that can be diagnosed by genetic testing of five genes known to be disease-causative (ATPV1B1 and ATPV0A4, FOXi1, SLC4A1 and WDR72). Incomplete distal renal tubular acidosis (idRTA) is defined as impaired urinary acidification that does not lead to overt metabolic acidosis and therefore can be diagnosed if patients fail to adequately acidify urine after an ammonium chloride (NH4Cl) challenge or other acid load tests. It is observed in 10-20% of calcium stone formers. It is still uncertain whether idRTA represents a distinct entity or it is part of the dRTA spectrum and whether it is caused by mutations in the same genes of overt dRTA. Heterozygous ATP6V1B1 pathogenic variants have been linked to idRTA, as well as mutations in SLC4A1. Method In this cross-sectional study we investigated a group of 23 stone formers whose clinical features were suspicious of idRTA: a history of nephrolithiasis or nephrocalcinosis with morning urinary pH &amp;gt; 5.8 in the absence of overt metabolic acidosis. They therefore underwent a simplified NH4Cl challenge and were found to have impaired urinary acidification ability. These patients were then analyzed by genetic testing with sequencing of 4 genes: SLC4A1, ATP6V1B1, ATP6V0A4 and FOXi1. Results Two unrelated individuals were found to have mutations in SLC4A1: 2 different variants in heterozygosis that had never been described before. The first patient was a 47-year old man, recurrent stone former (mainly apatite, but also some calcium oxalate), with hypercalciuria but normal bone mineral density (BMD). His family history revealed 1 uncle with kidney stones. The second patient was a 56-year old woman with a diagnosis of osteogenesis imperfecta, a history of reduced BMD and severe restrictive ventilation disorder and passed 1 stone (35% apatite, 65% CaOx). She was found to have bilateral nephrocalcinosis and hypocitraturia. Her family history revealed a sister with kidney stones. Conversely, 21 patients did not show any mutations for the genes sequenced, leading to a prevalence of genetic mutations of 8.7%. This is a much lower figure compared with overt dRTA, in which only 30% of patients with a clinical diagnosis of hereditary dRTA have no identified causative mutations in the currently known genes. Conclusion This suggests the involvement of other genes (WDR72 or others) or non-genetic tubular dysfunction in the pathogenesis of idRTA in stone formers.

Incomplete distal renal tubular acidosis in children.

To describe incomplete distal renal tubular acidosis (iDRTA) in paediatric patients, a term used for the diagnosis of patients who do not develop spontaneous overt metabolic acidosis but are unable to acidify the urine in response to an ammonium chloride load. Tests used to explore urinary acidification were revised. In addition, publications in English extracted from 161 entries yielded by a PubMed database search, using 'incomplete distal renal tubular acidosis' as keyword, were reviewed. Incomplete distal renal tubular acidosis has mostly been identified in adults with autoimmune diseases, nephrolithiasis, nephrocalcinosis and/or osteopenia. iDRTA has been reported in few paediatric patients with rickets, congenital abnormalities of kidney and urological tract and/or growth failure. The pathophysiological mechanisms potentially responsible for the defect of urinary acidification are discussed as well as the clinical and biochemical findings of iDRTA described in children. The presentation of iDRTA in children differs from adults. The clinical and biochemical features of iDRTA are not well characterised in paediatric patients. The detection of iDRTA in groups of population such as heterozygous carriers of primary DRTA gene mutations and children with hypocitraturia or hypercalciuria might be of clinical interest to better know the pathophysiology and natural history of iDRTA.

Clinical, Paraclinical Characteristics in Children with Renal Tubular Acidosis

This descriptive study describes the clinical, paraclinical characteristics in children with renal tubular acidosis. In this study, 36 children with renal tubular acidosis were hospitalized in the National Hospital of Pediatrics from June, 2012 to July, 2017. Among the patients, 64.0% were male; the male/female ratio was 1.8/1. The average age of the patients was 7.7 ± 4.6 years. There were 29 type 1 renal tubular acidosis patients (80.6%) and 7 type 2 renal tubular acidosis (19.6%). The most common clinical signs were slow weight gain (100%), polyuria and vomiting were 25.7%, excessive water drinking (16.7%), diarrhea (13.9%), weak lower limb (11.1%), and apnea (8.3%). The laboratory values on admission were: blood pH 7.23 ± 0.11; HCO3- 12.5 ± 5.07; serum sodium 136 ± 7mmol/l; potassium 2.9 ± 0.5 mmol/l; chloride 112 ± 9 mmol/l. The study concludes that 53.8% of the clinical, paraclinical characteristics in children with Renal Tubular Acidosis were inconspicuousness, which effected the children’s growth. The study recommends a long-term strategy for diagnosis and follow–up treatment of renal tubular acidosis.&#x0D; Keywords&#x0D; Renal tubular acidosis, Fanconi syndrome.&#x0D; References&#x0D; [1] Edyta Golembiewska and Kazimierz Ciechanowski, Renal tubular acidosis—underrated problem?, Acta biochimica polonica. 59(2) (2012) 213-215.[2] WHO (2011), Haemoglobin concentrations for the diagnosis of annaemia and assessment of severity, VMNIS, 1.[3] A.P. Sharma, R.K. Sharma, R. Kapoor, et al, Incomplete distal renal tubular acidosis affects growth in children, Nephrol Dial Transplant. 22 (10) (2007) 2879-2783.[4] WHO Child Growth Standards: Methods and development, tại trang web http://www.who.int/childgrowth/standards/technical_report/en/, truy cập ngày 30/10/2018.[5] A. Bagga Bajpai, P. Hari, A. Bardia, et al, Long-term outcome in children with primary distal renal tubular acidosis, Indian Pediatr. 42(4) 321 -328.[6] J.C. Chan, F. Santos, Renal tubular acidosis in children, Diagnosiseatment and prognosis., Am J Nephrol. 6(4) (2005) 289-294.[7] Symptoma Renal Tubular Acidosisuy, tại trang web https://www.symptoma.com/en/info/renal-tubular-acidosis, truy cập ngày 30/10/2018.[8] Julian Yaxley, Christine Pirrone, Review of the Diagnostic Evaluation of Renal Tubular Acidosis, Ochsner J. 16(4) (2016) 525-232.[9] Pramod Sood, Gunchan Paul, and Sandeep Puril, Interpretation of arterial blood gas, Indian J Crit Care Med. 14(2) (2010) 57-63.[10] J.L. Wilson, A.M. Butler, S. Farber, Dehydration and acidosis with calcification at renal tubules, The Journal of Pediatrics. 8 (2006) 489-494.&#x0D;

Renal involvement in primary Sjogren's syndrome: a prospective cohort study.

The objective of the study is to prospectively evaluate the spectrum of clinical and subclinical renal involvement in patients with primary Sjogren's syndrome (pSS). Of the 174 patients screened, seventy patients with pSS underwent renal function tests, urine examination, renal ultrasound, arterial blood gases, urine pH followed by urine acidification test and renal biopsy (if indicated). Renal tubular acidosis (RTA) was treated with alkali replacement and moderate-severe tubulointerstitial nephritis (TIN) was treated with oral prednisolone. Sixty-two patients completed 1-year follow-up. A comparison was made between patients with and without renal involvement. Thirty-five (50%) patients had renal involvement. They had a lower baseline eGFR (71.85 ± 18.04 vs. 83.8 ± 17, p = 0.005). Twenty-nine patients had RTA (25 complete and 4 incomplete). Eleven patients had urinary abnormalities. Patients with RTA (n = 29) were younger (34.9 ± 9 vs. 42 ± 11.3, p = 0.006), had fewer articular (34% vs. 78%, p = 0.001) and ocular sicca (62% vs. 88%, P = 0.01) than those without RTA (n = 41) and commonly presented with hypokalemic paralysis. On biopsy, TIN (9/17) and IgA nephropathy (3/17) were most common. On follow-up, there was no clinically significant change in eGFR; however, one patient with renal calculi and incomplete distal renal tubular acidosis (dRTA) progressed to complete dRTA. Two patients treated with steroids had marginal improvement in eGFR. Renal involvement in pSS is under-recognized with the most common manifestation being RTA presenting with hypokalemic paralysis. These patients are younger with less articular and sicca symptoms. Subclinical RTA may progress to complete RTA. Renal biopsy should be considered in all patients with renal involvement.

Sjögren's, Renal Tubular Acidosis and Osteomalacia - An Asian Indian Series.

Objective: To study the profile of Renal Tubular Acidosis (RTA) in Asian Indian patients with Primary Sjogren's Syndrome (pSS). Methods: The Electronic medical records of patients with a diagnosis of pSS seen between 2003 and 2010 at our tertiary care teaching hospital were screened for RTA. Clinical features, immunological profile, acid-base balance and electrolyte status, 25-hydroxyvitamin D (25(OH) D3) levels, histopathological changes in minor salivary gland biopsy samples and radiological findings were retrieved. RTA was diagnosed in cases of hyperchloremic metabolic acidosis with urinary pH values higher than 5.5. Those with known features suggestive of RTA including hypokalemic paralysis, hyperchloremia and nephrocalcinosis without acidosis were defined as incomplete RTA. Results: Of the 380 patients with clinically suspected pSS, 25 had RTA. The median age was 32 (18-60) years. Nineteen patients had complete RTA. Six had incomplete RTA. Only 10 patients (40%) had symptoms related to RTA at presentation. Sixteen patients (64%) had present or past history of hypokalemic paralysis. Pseudofractures were seen in 7 patients and an additional 2 had subclinical radiological osteomalacia. Majority of the patients (61.2%) had a normal 25(OH) D3 level. Those with osteomalacia had significantly lower serum phosphate, blood ph and higher alkaline phosphatase. Serum calcium and 25(OH) D3 levels were not significantly different between patients with osteomalacia and those without. Conclusion: Most patients were asymptomatic for RTA inspite of clinically overt and elicitable features. Skeletal manifestation was a common finding in patients with Sjogren and RTA, despite normal levels of 25 (OH) D3 in a majority.

Metabolic profile and impact of diet in patients with primary hyperoxaluria.

The primary goal of this pilot study was to evaluate metabolic characteristics and to examine the impact of diet in patients with primary hyperoxaluria (PH) under controlled, standardized conditions. Four patients with genetically confirmed PH collected 24h urines on their habitual, self-selected diets and on day 1, 6, 7, 8, and 11 under controlled, standardized conditions. The [13C2]oxalate absorption, calcium, and ammonium chloride loading tests were performed. While none of the patients had abnormal findings from the calcium loading test, incomplete distal renal tubular acidosis (RTA) was diagnosed in each of the four patients. Dietary intervention resulted in a significant decrease in urinary oxalate expressed as molar creatinine ratio (mmol/mol) between 30 and 40% in two of four patients. The evaluation of dietary records revealed a high daily intake of oxalate-rich foods as well as gelatin-containing sweets and meat products, rich sources of hydroxyproline, under the habitual, self-selected diets of the two responders. Intestinal oxalate hyperabsorption of 12.4% in one of the two patients may have additionally contributed to the increased urinary oxalate excretion under the individual diet. Our pilot data indicate that patients with PH may benefit from a restriction of dietary oxalate and hydroxyproline intake. Further research is needed to define the role of distal RTA in PH and to evaluate the hypothesis of an acquired acidification defect.

Targeted deletion of the Ncoa7 gene results in incomplete distal renal tubular acidosis in mice.

We recently reported that nuclear receptor coactivator 7 (Ncoa7) is a vacuolar proton pumping ATPase (V-ATPase) interacting protein whose function has not been defined. Ncoa7 is highly expressed in the kidney and partially colocalizes with the V-ATPase in collecting duct intercalated cells (ICs). Here, we hypothesized that targeted deletion of the Ncoa7 gene could affect V-ATPase activity in ICs in vivo. We tested this by analyzing the acid-base status, major electrolytes, and kidney morphology of Ncoa7 knockout (KO) mice. We found that Ncoa7 KO mice, similar to Atp6v1b1 KOs, did not develop severe distal renal tubular acidosis (dRTA), but they exhibited a persistently high urine pH and developed hypobicarbonatemia after acid loading with ammonium chloride. Conversely, they did not develop significant hyperbicarbonatemia and alkalemia after alkali loading with sodium bicarbonate. We also found that ICs were larger and with more developed apical microvilli in Ncoa7 KO compared with wild-type mice, a phenotype previously associated with metabolic acidosis. At the molecular level, the abundance of several V-ATPase subunits, carbonic anhydrase 2, and the anion exchanger 1 was significantly reduced in medullary ICs of Ncoa7 KO mice, suggesting that Ncoa7 is important for maintaining high levels of these proteins in the kidney. We conclude that Ncoa7 is involved in IC function and urine acidification in mice in vivo, likely through modulating the abundance of V-ATPase and other key acid-base regulators in the renal medulla. Consequently, mutations in the NCOA7 gene may also be involved in dRTA pathogenesis in humans.

Sjögren's, Renal Tubular Acidosis And Osteomalacia - An Asian Indian Series.

Objective: To study the profile of Renal Tubular Acidosis (RTA) in Asian Indian patients with Primary Sjögren's Syndrome (pSS). Methods: The Electronic medical records of patients with a diagnosis of pSS seen between 2003 and 2010 at our tertiary care teaching hospital were screened for RTA. Clinical features, immunological profile, acid-base balance and electrolyte status, 25-hydroxyvitamin D (25(OH) D3) levels, histopathological changes in minor salivary gland biopsy samples and radiological findings were retrieved. RTA was diagnosed in cases of hyperchloremic metabolic acidosis with urinary pH values higher than 5.5. Those with known features suggestive of RTA including hypokalemic paralysis, hyperchloremia and nephrocalcinosis without acidosis were defined as incomplete RTA. Results: Of the 380 patients with clinically suspected pSS, 25 had RTA. The median age was 32 (18-60) years. Nineteen patients had complete RTA. Six had incomplete RTA. Only 10 patients (40%) had symptoms related to RTA at presentation. Sixteen patients (64%) had present or past history of hypokalemic paralysis. Pseudofractures were seen in 7 patients and an additional 2 had subclinical radiological osteomalacia. Majority of the patients (61.2%) had a normal 25(OH) D3 level. Those with osteomalacia had significantly lower serum phosphate, blood ph and higher alkaline phosphatase. Serum calcium and 25(OH) D3 levels were not significantly different between patients with osteomalacia and those without. Conclusion: Most patients were asymptomatic for RTA inspite of clinically overt and elicitable features. Skeletal manifestation was a common finding in patients with Sjögren and RTA, despite normal levels of 25 (OH) D3 in a majority.

AB0808 Incomplete Distal Renal Tubular Acidosis in Patients with Osteo-Porosis/Osteopenia – Prevalence and Treatment

BackgroundImpaired renal H+ ion secretion causes acid retention which is known to promote bone dissolutionObjectivesTo prospectively assess the prevalence of distal renal tubular acidosis (dRTA) in low bone mass patients...

Medullary sponge kidney and isolated hemihyperplasia

The term hemihyperplasia refers to an enlargement of body parts beyond the normal asymmetry. Hemihyperplasia can be isolated or associated with various well-described malformation syndromes. Medullary sponge kidney (MSK) has been described with isolated and syndromic hemihyperplasia; the actual prevalence is not known The hemi hypertrophy can be so subtle that it may be easily overlooked. MSK need not be limited to the side of hemihyperplasia – most often it is bilateral. Around 33 cases has been reported from different parts of the world of which 15 cases are isolated hemi hyperplasia (IHH), the remaining occurring in the context of various malformation syndromes So far only one case has been reported from India. We report a case of IHH involving right side of the body, recurrent renal stones, incomplete distal renal tubular acidosis hypercalciuria and imaging showing bilateral MSKs.

Bilateral Giant Ureteric and Staghorn Calculi in a Patient with Incomplete Distal Renal Tubular Acidosis

Bilateral Giant Ureteric and Staghorn Calculi in a Patient with Incomplete Distal Renal Tubular Acidosis

Ruolo dell'anidrasi carbonica e meccanismi di acidificazione renale nella nefrolitiasi calcica

La nefrolitiasi è una malattia cronica e recidivante che interessa dal 6% al 10% della popolazione generale. Esiste un'associazione diretta tra difetti di acidificazione tubulare nefrolitiasi e nefrocalcinosi. L'acidosi tubulare determina ipercalciuria ed ipocitraturia, fattori che insieme al pH urinario alcalino favoriscono la precipitazione di cristalli di fosfato di calcio. I difetti di acidificazione possono essere secondari a numerose patologie ma anche essere di natura iatrogena. Sono numerosi i farmaci noti e meno noti che possono determinare un quadro simile all'acidosi tubulare renale distale (ATRd) incompleta. È pertanto doveroso sospettare di fronte ad un soggetto con nefrolitiasi e/o microcalcificazioni la presenza di un disturbo tubulare primitivo o secondario.

Metabolic evaluation in first-time renal stone formers in north India: A single center study

The risk of stone recurrence in first-time stone formers (FTSF) varies from 26% to 53%. There is no consensus regarding metabolic evaluation in these individuals. We evaluated the metabolic abnormalities in first-time renal stone forming patients in North India. Thirty-nine patients, (29 males and 10 females with mean age 39.3 ± 12.9 years) who presented with nephrolithiasis for the first time were evaluated. We evaluated the calcium homeostasis [serum corrected total calcium, phosphorous, creatinine, alkaline phosphatase, albumin, parathormone (iPTH), 25-hydroxy cholecalciferol (25(OH)D 3 ), 1-25 di-hydroxy cholecalciferol (1,25(OH) 2 D 3 )] and performed the calcium load test also. Two 24-h urine collections were taken for citrate, oxalate, calcium and uric acid. Ammonium chloride loading test for diagnosis of distal renal tubular acidosis was performed in all patients. For each of the diagnostic categories, descriptive statistics were computed for all biochemical variables. A two-tailed P-value <0.05 was regarded as significant. Metabolic abnormalities were detected in 92.3% of the patients (n = 39) studied. Of them, almost 60% had two or more metabolic abnormalities. The most common metabolic abnormality was hypo-citraturia (82%), followed by hyper-oxaluria (56%) and hyper-calciuria (41%). Five percent of the patients had incomplete renal tubular acidosis, signifying the importance of the ammonium chloride loading test in patients with renal stones. None of the study patients were detected to have primary hyperparathyroidism. In three patients, the etiology could not be detected. Our findings suggest that an underlying disorder is present in majority of first-time renal stone formers. Intervention with appropriate treatment can prevent recurrences. Hence, comprehensive metabolic evaluation is recommended in all FTSF.

Hereditary hypophosphatemic rickets with hypercalciuria: case report.

We report a case of a male aged 50 years who consulted for renal disease recurrent lithiasis and nephrocalcinosis. The clinical examination showed external signs of rickets/osteomalacia and biochemical data as well as a severe loss of renal phosphate with hypophosphatemia, normal 25 OH vitamin D, high 1,25 OH vitamin D and hypercalciuria. Parathyroid hormone was low and renal ultrasound confirmed the existence of severe bilateral medullary nephrocalcinosis. They also found incipient chronic renal failure and incomplete renal tubular acidosis, both secondary to nephrocalcinosis and unrelated to the underlying disease. The molecular study found a change in homozygosity in intron 5 of gene SLC34A3 (NM_080877.2:c[ 448 +5G&gt;A] + [ 448 +5G&gt;A] ). His three children were carriers of the same variant in heterozygosis and although they were clinically asymptomatic two of them had hypercalciuria. All these data suggest that the patient had hereditary hypophosphataemic rickets with hypercalciuria (HHRH) secondary to an alteration in the sodium dependent phosphate cotransporter located in proximal tubule (NaPi-IIc). The HHRH is transmitted by autosomal recessive inheritance and is an extremely rare form of hypophosphatemic rickets. The diagnosis and treatment are essential to prevent bone sequelae of rickets and nephrocalcinosis. A correct differential diagnosis with other forms of hypophosphatemic rickets has implications on the treatment, as the management based only on phosphorus supplementation usually corrects all clinical and biochemical abnormalities, except for the loss of phosphorus in the urine. The exogenous supply of calcitriol, as advised in other hypophosphatemic rickets, may induce renal calcium deposits and nephrocalcinosis and worsens the prognosis.