Renal Tubular Acidosis

Renal Tubular Acidosis



Basic Information image



Definition


Renal tubular acidosis (RTA) is a group of disorders affecting the renal tubular cells that result in hyperchloremic metabolic acidosis with a normal anion gap.



Epidemiology



Associated Conditions and Disorders




• Hyperchloremic metabolic acidosis with a normal anion gap


• Weight loss, unthriftiness



Clinical Presentation



Disease Forms/Subtypes




• Type I: Distal or classic RTA (H+ retention)


• Type II: Proximal RTA (HCO3 wasting)



History, Chief Complaint




• Depression


• Poor performance


• Anorexia


• Weight loss


• Unthriftiness


• Dull hair coat


• Weakness


• Colic


• Ataxia


• Polyuria or polydipsia



Physical Exam Findings




• Mild dehydration


• Mild abdominal distension


• Muscular weakness


• Tachypnea


• Tachycardia



Etiology and Pathophysiology




• Etiology: Underlying cause is usually undetermined, but is generally acquired


image Renal tubular toxins: Heavy metals, ethylene glycol, drugs (gentamicin, cephalosporins, tetracyclines, salicylate)

image Neoplasia

image Hypoparathyroidism

image Pyelonephritis

image Ischemia-induced renal failure

image Hypoaldosteronism or aldosterone resistance

• Pathophysiology


image Type I (distal or classic RTA) is caused by an inability of the distal tubule cells to secrete H+ or to produce acidic urine. There is excessive K+ secretion and severe hypokalemia.

image Type II (proximal RTA) is caused by a failure of HCO3− resorption in the proximal tubule with subsequent loss of HCO3− into urine. The proximal tubule is the site where the majority of filtered HCO3– is reabsorbed via Na+ and H+ exchange and the breakdown of carbonic acid to carbon dioxide and water under the influence of carbonic anhydrase. Hydrogen ions are usually secreted when HCO3− ion is reabsorbed. Failure to reabsorb HCO3− results in excessive urinary losses, basic urine pH, and systemic acidosis.

image Hyperchloremia develops because of renal conservation of chloride to maintain electroneutrality consequent to HCO3− loss.
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Jul 24, 2016 | Posted by in SMALL ANIMAL | Comments Off on Renal Tubular Acidosis

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