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SUMMARY

Pseudohypoaldosteronism Type 1 presents in neonatal period with severe hyponatremic dehydration and elevated aldosterone levels. The autosomal recessive form is due to mutations in the genes for the amiloride-sensitive epithelial Na channel. Defective sodium resorption in the sweat glands leads to elevated sweat sodium and chloride levels. An increase in the sodium concentration in the airway surface liquid probably promotes the growth of Pseudomonas aeruginosa, and reduces killing of Pseudomonas aeruginosa, leading to Pseudomonas aeruginosa lung disease. Lung involvement in patients with pseudohypoaldosteronism type 1 appears to be related to mutations in the alpha-subunit of ENaC, at least based on current evidence. However, lung disease seems milder than in CF, with no reports of bronchiectasis in patients to date.

DISCUSSION POINTS

The long-term prognosis of pseudohypoaldosteronism type 1 was discussed. It was noted that the oldest patients with pseudohypoaldosteronism type 1 and lung disease was 8 years of age, and most CF patients in this age group donÕt have bronchiectasis either, so further follow-up will be needed to determine whether these patients will develop bronchiectasis.

At present, treatment of these patients seems to be similar to the treatment of CF patients. Further research, looking particularly into the electrolyte composition of the airway surface liquid in CF patients, will be needed to determine whether airway colonization with Pseudomonas aeruginosa in these two conditions is related to common abnormalities in the electrolyte composition of the airway surface liquid or other host-related abnormalities in these two conditions. Members of the group inquired whether patients with pseudohypoaldosteronism type 1 and Pseudomonas aeruginosa lung disease have mucoid Pseudomonas, and whether conversion to mucoidy was also related to host/environmental factors, and I noted that I wasnÕt certain whether patients with pseudohypoaldosteronism type 1have mucoid Pseudomonas aeruginosa.



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