Tuesday, June 1, 2010


Point the odd one out!

Proximal Renal Tubular Acidosis
  0 (0%)
Gordon's Syndrome
  13 (68%)
Toluene Intoxication
  4 (21%)
  2 (10%)
  0 (0%)

I think that most of you got this one right. Yes, it is Gordon's syndrome. 
Proximal RTA, Toluene Intoxication, Diarrhea and Ureteroileostomy are all associated with normal hyperchloremic anion gap met acidosis but with low serum K.  Gordon's syndrome is usually associated with normal or high serum K.
Leaving Proximal RTA aside, lets discuss the other options a little.
Gordon's syndrome is also known as pseudoaldosteronism Type II. Recently defects in the WNK1 and WNK4 members of the serine threonine kinases have been identified to cause this AD disease.  Normally these WNKS inhibut the thiazide sensitive Na-cl co transporter.  In Gordon's syndrome, there are mutations in this kinases leading to over active channel and gain of function.  This leads to excessive chloride and sodium re absorption and can lead to a low renin and low aldo- hypertension.  Think of this disease as Gitelman's Syndrome with HTN.  You also see though short stature, dental abnormalities, low excretion of Na and a metabolic acidosis. There is hyperkalemia and this is due to the diminished sodium delivery to the cortical collecting tubule at the ROMK.  You usually treat with low salt diet and/or thiazide diuretics.
In Toluene Intoxication, one sees met acidosis, hypokalemia and this is reversible. This is due to hippuric acid and other organic acid by products of toluene and that leads to a positive urine anion gap and can mimic distal RTA.  Toluene intoxication can lead to a metabolic acidosis via two mechanisms. First,
it is metabolized to hippuric acid by way of benzoic acid,both of which are found in the serum of patients who abuse toluene. If renal elimination of hippuric acid is impaired or hippuric acid production is high relative to renal clearance, the molecule builds up and can produce an anion gap metabolic acidosis. Toluene intoxication may also lead to a normal anion( mostly seen) gap acidosis by impairing renal elimination of ammonium ion, the primary carrier for excess hydrogen ions.  The urine osmolar gap might be the only way one can perhaps suspect a toluene intoxication and by history of course from a true distal RTA. 
Hyperchloremic acidosis is observed after ureterosigmoidostomy or ureteroileostomy. Acidosis is more common with the former procedure because of the large surface area and transit time involved in the small bowel. The presence of hyperchloremic acidosis after ureteroileostomy suggests obstruction of the conduit. Usually, most of these are with hypokalemia but if there is severe obstruction, hyperkalemia could ensue. 


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