Renal tubular acidosis.

Renal tubular acidosis (RTA) is a form of metabolic acidosis due to abnormal alkali (bicarbonate) loss by the kidneys or their failure to excrete net acid. While the latter does occur in chronic renal failure, the term RTA is usually applied only when the glomerular filtration rate is normal or near normal. As well as a cause of metabolic acidosis, RTA often presents as renal stone disease with nephrocalcinosis, rickets/osteomalacia, and growth retardation in children. In this brief review, we have summarized the classification, clinical features and the underlying cell and molecular pathophysiology of RTA. However, despite significant advances in our understanding of the mechanisms of RTA, its treatment is still empirical and based largely on alkali replacement therapy; but its wider significance in renal stone and bone disease is becoming increasingly recognized.

Renal tubular acidosis: developments in our understanding of the molecular basis.

Renal tubular acidosis is a metabolic acidosis due to impaired acid excretion by the kidney. Hyperchloraemic acidosis with a normal anion gap and normal (or near normal) glomerular filtration rate, and in the absence of diarrhoea, defines this disorder. However, systemic acidosis is not always evident and renal tubular acidosis can present with hypokalaemia, medullary nephrocalcinosis and recurrent calcium phosphate stone disease, as well as growth retardation and rickets in children, or short stature and osteomalacia in adults. Renal dysfunction in renal tubular acidosis is not always confined to acid excretion and can be part of a more generalised renal tubule defect, as in the renal Fanconi syndrome. Isolated renal tubular acidosis is more usually acquired, due to drugs, autoimmune disease, post-obstructive uropathy or any cause of medullary nephrocalcinosis. Less commonly, it is inherited and may be associated with deafness, osteopetrosis or ocular abnormalities. The clinical classification of renal tubular acidosis has been correlated with our current physiological model of how the nephron excretes acid, and this has facilitated genetic studies that have identified mutations in several genes encoding acid and base ion transporters. In vitro functional studies of these mutant proteins in cell expression systems have helped to elucidate the molecular mechanisms underlying renal tubular acidosis, which ultimately may lead to new therapeutic options in what is still treatment only by giving an oral alkali.

[Renal tubular acidosis (RTA)].

Renal tubular acidosis (RTA) is applied to a group of transport defects involving the reabsorption of bicarbonate (proximal RTA or type II), the excretion of hydrogen ion (distal RTA or type I), or both (type III). Aldosteron deficiency and resistant state to aldosteron form hyperkalemic RTA which is called type IV RTA. A large number of etiologies of RTA have been identified. Almost all RTA in childhood are congenital. In contrast, almost all RTA in adulthood are secondary. Two renal complications such as low molecular weight proteinuria and renal cyst formation have recently been described in distal RTA. Molecular defects of RTA will be identified in the near future.

Acidosis tubular renal tipo I / Renal tubular acidosis type I

Se presenta el caso de una paciente de sexo femenino, con edad de seis años, la cual a su ingreso presenta la historia de seis meses de poliuria, flacidesz de miembros inferiores y durante su hospitalización se encontró, además, hipokalemia, acidosis metabólica, calciuria y nefrocalcinosis al USG renal. Su manejo con potasio y bicarbonato de sodio produjo una satisfactoria respuesta en la paciente. Se discuten las caracteristicas clínicas

[Renal tubular acidosis in children]. / Acidose tubulaire rénale chez l'enfant.

Renal tubular acidosis represents a heterogenous group of disorders with various etiologies and mechanisms. The physiopathologic basis of each type of renal tubular acidosis is reviewed, focusing on the laboratory investigations necessary to define the nature of the hyperchloremic renal tubular acidosis. Clinically, the four types of renal tubular acidosis can be associated with complications such as osteomalacia, urolithiasis and failure to thrive. Very often, the chronic administration of alkali results in normal growth and development, and greatly reduces the risk of stone formation or nephrocalcinosis.

[Renal tubular acidosis].

Renal tubular acidosis (RTA) can be separated into three main types: distal RTA (the defect in the excretion of hydrogen ion), proximal RTA (the defect in the reabsorption of bicarbonate), and hyperkalemic RTA. Some patients present combined types of proximal and distal RTA. Most of the pediatric patients with RTA manifest failure to thrive. They have hyperchloremic metabolic acidosis and normal plasma anion gap. Fractional excretion of bicarbonate is below 5% in dRTA and over 15% in pRTA. Renal complications of dRTA are nephrocalcinosis, renal calculi, renal cysts and reversible low molecular weight proteinuria. The patient with isolated pRTA is very rare.

Manifestación de acidosis tubular renal tipo I (distal) como insuficiencia respiratoria

Describimos tres casos de acidosis tubular renal del adulto (ATR), asociada a hipocalemia e insuficiencia respiratoria. Este es el primer informe de esta asociación reportado en la literatura colombiana. Recomendamos en cualquier paciente que se presente con parálisis e insuficiencia respiratoria aguda una evaluación del potasio sérico