Hyperammonaemia due to primary hyperparathyroidism-related renal tubular acidosis with incidental hypovitaminosis-D (original) (raw)
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Journal of the American Society of Nephrology, 2002
The term renal tubular acidosis (RTA) is applied to a group of transport defects in the reabsorption of bicarbonate (HCO 3 Ϫ), the excretion of hydrogen ion (H ϩ), or both. This condition was first described in 1935 (1), confirmed as a renal tubular disorder in 1946 (2), and designated "renal tubular acidosis" in 1951 (3). The RTA syndromes are characterized by a relatively normal GFR and a metabolic acidosis accompanied by hyperchloremia and a normal plasma anion gap. In contrast, the term uremic acidosis is applied to patients with low GFR in whom metabolic acidosis is accompanied by normo-or hypochloremia and an increased plasma anion gap.
Renal tubular acidosis--underrated problem?
Acta biochimica Polonica, 2012
Renal tubular acidosis (RTA) is a hyperchloremic metabolic acidosis characterized by a normal anion gap and normal (or near normal) glomerular filtration rate in the absence of diarrhoea. Inherited isolated forms of renal tubular acidosis are not common. However, they can also be a part of a more generalized tubule defect, like in Fanconi syndrome. In recent years more and more gene mutations have been found which are associated with RTA (mutations in the gene SLC4A4, encoding a Na(+)-HCO(3)(-) cotransporter (NBC-1); in the gene SLC4A1, encoding Cl(-)/HCO3(-) exchanger (AE1); in the gene ATP6B1, encoding B1 subunit of H(+)-ATPase; in the gene CA2 encoding carbonic anhydrase II; and others) and allow better understanding of underlying processes of bicarbonate and H(+) transport. Isolated renal tubular acidosis can be frequently acquired due to use of certain drug groups, autoimmune disease or kidney transplantation. As the prevalence of acquired forms of RTA is common, new therapeuti...
Hyperkalemic Forms of Renal Tubular Acidosis: Clinical and Pathophysiological Aspects
Advances in chronic kidney disease, 2018
In contrast to distal type I or classic renal tubular acidosis (RTA) that is associated with hypokalemia, hyperkalemic forms of RTA also occur usually in the setting of mild-to-moderate CKD. Two pathogenic types of hyperkalemic metabolic acidosis are frequently encountered in adults with underlying CKD. One type, which corresponds to some extent to the animal model of selective aldosterone deficiency (SAD) created experimentally by adrenalectomy and glucocorticoid replacement, is manifested in humans by low plasma and urinary aldosterone levels, reduced ammonium excretion, and preserved ability to lower urine pH below 5.5. This type of hyperkalemic RTA is also referred to as type IV RTA. It should be noted that the mere deficiency of aldosterone when glomerular filtration rate is completely normal only causes a modest decline in plasma bicarbonate which emphasizes the importance of reduced glomerular filtration rate in the development of the hyperchloremic metabolic acidosis associa...
Clinical and laboratory approaches in the diagnosis of renal tubular acidosis
Pediatric nephrology (Berlin, Germany), 2015
In the absence of a gastrointestinal origin, a maintained hyperchloremic metabolic acidosis must raise the diagnostic suspicion of renal tubular acidosis (RTA). Unlike adults, in whom RTA is usually secondary to acquired causes, children most often have primary forms of RTA resulting from an inherited genetic defect in the tubular proteins involved in the renal regulation of acid-base homeostasis. According to their pathophysiological basis, four types of RTA are distinguished. Distal type 1 RTA, proximal type 2 RTA, mixed-type 3 RTA, and type 4 RTA can be differentiated based on the family history, the presenting manifestations, the biochemical profile, and the radiological findings. Functional tests to explore the proximal wasting of bicarbonate and the urinary acidification capacity are also useful diagnostic tools. Although currently the molecular basis of the disease can frequently be discovered by gene analysis, patients with RTA must undergo a detailed clinical study and labo...
A new classification for renal defects in net acid excretion
American Journal of Kidney Diseases, 1997
The traditional classification of the group of disorders called renal tubular acidosis (RTA) into proximal and distal subclasses is based on which nephron segment is thought to have an abnormal function. Nevertheless, such a distinction may not be correct and also does not characterize the pathophysiology of the renal acidosis in each patient. In this article, we propose an alternative classification, one that is based on the component of net acid excretion that is abnormal. We also suggest expanding the definition of net acid excretion to include a term that describes the renal handling of metabolizable organic anions because their loss in the urine represents the loss of "potential bicarbonate." Because a low rate of excretion of ammonium (NH4 ÷) is present in patients with both distal and isolated proximal RTA, our initial clinical step in patients with hyperchloremic metabolic acidosis (HCMA) is to evaluate the rate of excretion of NH4 ÷. The basis for a low rate of excretion of NH4 ÷ is shown by examining the urine pH. If the urine pH is low, further studies are performed to determine why the availability of NH3 is low; if the urine pH is high, further investigations are initiated to examine if the defect in H ÷ secretion involves the proximal or the distal nephron. Conversely, if the rate of excretion of NH4 ÷ is high in a patient with HCMA, a component of the degree of acidosis could be attributable to a high rate of excretion of metabolizable organic anions. Case examples are provided to illustrate the approach and its implications for future molecular studies.