Distal renal tubular acidosis secondary to vesico-ureteric reflux: A case report with review of literature.

Vesicoureteric reflux (VUR) is the most common congenital anomaly of the urinary tract that occurs in 30%-50% of children presenting with recurrent urinary tract infections. Long-standing untreated VUR results in renal scarring and hydronephrotic changes ultimately leading to chronic renal failure and arterial hypertension. However, it may also result in diffuse tubulopathy compromising the concentrating capacity of tubules and urinary acidification defects. Renal tubular dysfunction should be considered in all children with VUR presenting with failure to thrive, rickets, bony deformity/pain, hypokalemia, and metabolic acidosis. We report such a case of a 16-year-old male adolescent who presented with rickets, failure to gain weight and height, bony pains, and muscle weakness with a history of VUR. On investigation, he was found to have normal anion gap metabolic acidosis with hypokalemia suggestive of distal renal tubular acidosis. He responded well to oral alkali and potassium replacement therapy.

An Exceptional Neurosurgical Presentation of a Patient with Osteopetrosis.

BACKGROUND: Osteopetrosis (OP) is a varied clinical condition caused by malfunction or insufficient development of osteoclasts, or both. Neurologic findings can occur because of osteopetrotic conditions restricting neural foramina through which the spinal cord, cranial nerves, or major vascular structures traverse the skull. Renal tubular acidosis (RTA) is a well-documented condition with OP. However, Chiari I malformation is rarely reported concomitantly with OP. CASE DESCRIPTION: We present a patient with a known RTA who was admitted with a rapid progressive tetraparesis within 24 hours. Clinical and radiologic evaluation of the patient revealed OP with RTA together with Chiari I malformation and holocord hydromyelia. Management of the patient was started with correction of severe hypokalemia (K: 1.4 mEq/L), which resulted in dramatic improvement in tetraparesis. Two days later, a posterior fossa bone decompression with ventriculoperitoneal shunt placement during the same session led to prominent decrease in size of the ventricles and the hydromyelia on long-term follow-up. CONCLUSIONS: Patients with OP can exhibit many clinical conditions. However, our case involved an unusual and rapid progressive tetraparesis, which could confuse the management as necessitating an emergent posterior fossa decompression. Stabilizing the metabolic status of the patient facilitated elective surgery, which further improved patient's neurologic findings and diminished hydromyelia on long-term follow-up.

Renal histopathology of stone-forming patients with distal renal tubular acidosis.

To define the renal tissue changes in stone-forming patients with distal renal tubular acidosis (dRTA), we performed intra-operative papillary and cortical biopsies in five patients. The main abnormalities were plugging of inner medullary collecting ducts (IMCD) and Bellini ducts (BD) with deposits of calcium phosphate in the form of apatite; epithelial cell injury and loss was marked. Plugged ducts were surrounded by interstitial fibrosis, but the fibrosis was generalized, as well, and was a main feature of the histopathology even when plugging was not present. In contrast, common idiopathic calcium oxalate stone formers (SF) never manifest intra-tubule crystals or interstitial fibrosis. Patients with brushite (calcium monohydrogen phosphate) stones and those with cystine stones have many fewer IMCD and BD plugged with apatite (or cystine, in cystinuria), and interstitial fibrosis is limited to the regions around plugged ducts. Patients with dRTA often present a radiographic picture of nephrocalcinosis. Our direct surgical observations reveal that these may be surgically removable stones, especially in patients with well preserved renal function. In all, dRTA SF have a more diffuse papillary renal disease than other SF thus studied, and are also unusual for the degree of interstitial fibrosis.

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.

Marble brain disease in two Saudi Arabian siblings.

Marble brain disease, also known as Guibaud-Vainsel syndrome, is a syndrome consisting primarily of renal tubular acidosis, cerebral calcification and osteopetrosis. The majority of reports originate from the Middle East. It is an autosomal recessive condition owing to carbonic anhydrase type II deficiency in renal and brain cells with a variant form of osteopetrosis. We report two siblings with this condition from Saudi Arabia. Both cases improved in both somatic growth and mental development after commencing treatment for renal tubular acidosis in the form of alkaline therapy and potassium supplementation.

Secondary erythrocytosis associated with distal renal tubular acidosis.

AIMS: Diagnosis and classification of renal tubular acidosis (RTA) have traditionally been made on the basis of functional studies. Despite recent expanding knowledge about the molecular abnormalities involved in renal bicarbonate (HCO3-) and H+ transport, the pathophysiology of secondary erythrocytosis in association with distal RTA remains obscure. CASE HISTORY: A 2-month-old boy with severe hyperchloremic metabolic acidosis with positive urine anion gap was diagnosed with distal RTA. Replacement therapy with sodium bicarbonate and potassium citrate succeeded in improving his metabolic acidosis and growth. His renal function remained normal. He had persistent erythrocytosis. CONCLUSION: Secondary erythrocytosis is a rarely reported association of distal RTA. It may increase the risk of thromboembolism.

Reduced Tc-99m DMSA uptake in a patient with renal tubular acidosis: effect of acid-base imbalance.

Tc-99m dimercaptosuccinic acid (DMSA) is used as a renal cortical imaging agent to detect parenchymal abnormalities especially in children. Kidney uptake of DMSA provides an index for evaluation of a functional tubular mass, which depends on the renal blood flow and proximal tubular cell membrane transport function. We here report a boy with renal tubular acidosis, which has noticeably reduced uptake on his Tc-99m DMSA scintigraphy, despite a totally normal Tc-99m MAG-3 study. The case reported here clearly demonstrates a situation in which renal uptake of DMSA may be dissociated from a functional renal mass and the importance of acid-base balance which alters Tc-99m DMSA uptake.

Atypical distal renal tubular acidosis confirmed by mutation analysis.

In autosomal dominant distal renal tubular acidosis type I (dRTA) impaired hydrogen ion secretion is associated with metabolic acidosis, hyperchloremic hypokalemia, hypercalciuria, nephrocalcinosis, and/or nephrolithiasis. A retardation of growth is commonly observed. In this report we present a family with autosomal dominant dRTA with an atypical and discordant clinical picture. The father presented with severe nephrocalcinosis, nephrolithiasis, and isosthenuria but metabolic acidosis was absent. His 6-year-old daughter, however, suffered from metabolic acidosis, hypokalemia, and hypercalciuria. In addition, sonography revealed multiple bilateral renal cysts but no nephrocalcinosis. Mutation analysis of the AE1 gene coding for the renal Cl-/HCO3(-)-exchanger AE1 displayed a heterozygous Arg589Cys exchange in both patients but not in the healthy family members. This point mutation is frequently associated with autosomal dominant dRTA. Diagnosis of autosomal dominant dRTA is supported in this family by results of AE1 mutation analysis.

Benign methylmalonic acidemia in a sibship with distal renal tubular acidosis.

Two male infants born to consanguineous parents were investigated for feeding difficulties in the 1st month of life. Both were found to have distal renal tubular acidosis (dRTA) with hypercalciuria. Nephrocalcinosis was present in the first child but not in the second. Urinary organic acid profile demonstrated an excess of methylmalonic acid (MMA) in both children in the absence of any other organic acid. MMA mutase activity and propionate incorporation were normal. There have been no neurological symptoms in either child. The first child has normal growth and psychomotor development at 4 years. His brother, who also has significant gastrooesophageal reflux, has failed to thrive and currently requires nasogastric feeding and caloric supplements to maintain weight along the 3rd percentile. Urinary and plasma MMA continue to be raised in both cases. The association of increased urinary and plasma MMA and dRTA presenting in the 1st month of life has not previously been reported and may represent a new syndrome of autosomal recessive inheritance.

A novel neurological disorder with progressive CNS calcification, deafness, renal tubular acidosis, and microcytic anemia.

Progressive calcification of the brain and the spinal cord at early infantile onset was observed in two siblings. They showed growth failure, psychomotor deterioration, deafness, vestibular dysfunction, microcytic hypochromic anemia, abnormal ratios of lymphocyte subpopulations, and slightly decreased bicarbonate on blood gas analysis. Distal renal tubular acidosis was demonstrated in one of them. Carbonic anhydrase II activity was normal. This new hereditary disease might have a defect in a molecule that is present in brain, spinal cord, kidney and hematocytes and is involved in H+/HCO3- production or transport.

Renal tubular acidosis in pregnancy: case report and literature review.

Renal tubular acidosis is a rare form of chronic metabolic acidosis, which is either inherited as an autosomal dominant condition (Types 1, 2, and 3) or acquired. Its effects on pregnancy and vice versa are not known, but chronic acidosis may affect fetal bone growth and development. Chronic maternal acidosis may also lead to fetal distress, which should respond to correction of the maternal acidosis. The patient is a 20-year-old gravida 2, para 1-0-0-1, Hispanic female with distal renal tubular acidosis, diagnosed 1 year prior to this pregnancy after suffering from hypokalemic paralysis. During the pregnancy she required steadily increasing doses of potassium and bicarbonate, to maintain electrolyte balance. She delivered a healthy full-term female infant, weighing 2,892 g, with Apgars of 5 and 9 at 1 and 5 min, respectively, following an induction of labor for oligohydramnios. There was no evidence of intrapartum or neonatal distress, and the infant was discharged home with her mother on the first postpartum day in good health. Established renal tubular acidosis, which was adequately treated with bicarbonate and potassium supplementation during pregnancy, had no apparent ill effects on fetal or neonatal well-being in this case.

Dimercaptosuccinic acid distribution in renal tubular acidosis.

A 99Tcm dimercaptosuccinic acid (DMSA) scan performed after a urinary tract infection demonstrated an unusual pattern of isotope uptake, promoting further investigations leading to a diagnosis of renal tubular acidosis secondary to nephropathic cystinosis. This is known to affect isotope imaging but a unique feature in this undiagnosed case was the uncorrected metabolic acidosis, which had further altered the distribution of the DMSA. It is noteworthy because other patients referred for imaging with renal disease may also have abnormalities of acid base balance.

[Hyperechogenicity of the renal medulla in children: clinico-echographic correlations]. / Iperecogenicità della midollare renale nel bambino: correlazioni clinico-ecografiche.

Increased renal medullary echogenicity by renal ultrasound associated with hypercalciuria and nephrocalcinosis is often present in childhood. 17 children, 9 boys and 8 girls, aged from 8 months to 10 years were classified into three groups based on ultrasound findings according to Patriquin and Robitaille: type A faint hyperechogenic rim around the sides and tip of the medullary pyramid; type B more intense echogenic rim of the pyramids; type C intense echoes throughout the pyramid. Clinic-echographic correlations showed a pattern C in 4 children with distal renal tubular acidosis and in an infant treated with furosemide; pattern B in 3 patients having different types of tubulopathy associated with hypercalciuria; pattern A in 6 children with congenital tubulopathy and in 3 children treated with vitamin D. Abdominal X-rays detected medullary calcinosis in 2 (11.7%) of total 17 patients. Ultrasonography appears to be an important tool in early diagnosis of renal medullary nephrocalcinosis.

Causes of increased renal medullary echogenicity in Turkish children.

The primary disorders of 50 children with increased renal medullary echogenicity on renal ultrasound were studied; 28 girls and 22 boys aged from 1 month to 16 years were classified into four groups based on underlying disease and ultrasound findings. Group 1 was composed of 17 patients with distal renal tubular acidosis (34%); intense echoes throughout the pyramid were predominant. Group 2 consisted of 14 patients with vitamin D toxicity (28%) and an intense echogenic rim around the pyramids. Group 3 included 10 patients with different types of tubulopathies. A slight hyperechogenic rim around the sides and tip of the medullary pyramids was detected. Group 4 was made up of 9 patients with rare underlying conditions. Abdominal X-rays detected medullary calcinosis in only 12 (24%) of the total 50 patients. Ultrasonography appears to be an important tool in the early diagnosis of increased renal medullary echogenicity and medullary nephrocalcinosis.

Medullary nephrocalcinosis: sonographic findings in adult patients.

Medullary nephrocalcinosis occurs in various diseases as a non-specific renal manifestation. We present 5 patients (hypophosphataemic rickets, type 1 renal tubular acidosis, primary hyperparathyroidism, hypercalcaemia of unclear origin, chronic renal insufficiency requiring dialysis) in whom a medullary nephrocalcinosis was demonstrated by means of sonographically detectable changes in the renal medulla region. The sonographic appearance of medullary nephrocalcinosis is characterized by detection of echo-enhanced structures in the region of the renal pyramids. The presence of a medullary nephrocalcinosis can generally be confirmed with adequate reliability on the basis of sonographic findings and characteristic clinical pictures. In individual cases it is difficult to distinguish between medullary nephrocalcinosis and renal calyx calculi.