Two Cases of Mistaken Polyuria and Nephrocalcinosis in Infants with Glucose-Galactose Malabsorption: A Possible Role of 1,25(OH)2D3 .
OBJECTIVE
Glucose-galactose malabsorption (GGM) is a rare and potentially fatal disorder. The autosomal recessive mutation of the SGLT1 gene interferes with the active glucose transport in the gut resulting in osmotic diarrhea and failure to thrive (FTT). Two nonrelated infants with GGM are presented as well as a novel mutation in SGLT1.


METHODS
The first case consulted for FTT and presented with hypercalcemia and hypercalciuria. His mother had self-medicated with high doses of vitamin D. The second case consulted for macroscopic hematuria, and presented with dehydration and secondary acute kidney injury. In both cases, the profuse diarrhea, initially mistaken for polyuria, promptly resolved after the introduction of glucose-galactose-free milk. Investigations showed bilateral nephrocalcinosis and high levels of 1,25(OH)2D3 in both patients. We hypothesize that the upregulation of epithelial calcium channels (TRPV6) and 1,25(OH)2D3 are possible factors involved in the pathophysiology of nephrocalcinosis sometimes seen in GGM. Furthermore, a novel intronic SGLT1 mutation (c.207+2dup) is described.


CONCLUSIONS
These 2 cases demonstrate that a malabsorption disorder such as GGM can present with nephrocalcinosis and/or hypercalcemia, with increased 1,25(OH)2D3 levels in infants. Prompt recognition of GGM is sometimes difficult but crucial. .
Sainte Justine University Health Center, University of Montreal, Montreal, Québec, Canada.
Melissa
M
Fiscaletti
Sainte Justine University Health Center, University of Montreal, Montreal, Québec, Canada.
Marie-Jeanne
MJ
Lebel
Sainte Justine University Health Center, University of Montreal, Montreal, Québec, Canada.|Research Center of Sainte Justine Health Center, Montreal, Québec, Canada.
Nathalie
N
Alos
Sainte Justine University Health Center, University of Montreal, Montreal, Québec, Canada.
Geneviève
G
Benoit
Sainte Justine University Health Center, University of Montreal, Montreal, Québec, Canada.|Research Center of Sainte Justine Health Center, Montreal, Québec, Canada.
Prévost
P
Jantchou
D002117:Calcitriol / Q000097:blood*; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism; D002239:Carbohydrate Metabolism, Inborn Errors / Q000097:blood / Q000175:diagnosis / Q000235:genetics; D005183:Failure to Thrive / Q000097:blood / Q000175:diagnosis / Q000235:genetics; D005260:Female; D006801:Humans; D007223:Infant; D008286:Malabsorption Syndromes / Q000097:blood / Q000175:diagnosis / Q000235:genetics; D008297:Male; D009397:Nephrocalcinosis / Q000097:blood / Q000175:diagnosis / Q000235:genetics; D011141:Polyuria / Q000097:blood / Q000175:diagnosis / Q000235:genetics; D051269:Sodium-Glucose Transporter 1 / Q000235:genetics / Q000378:metabolism; D050916:TRPV Cation Channels / Q000235:genetics / Q000378:metabolism
D015220:Calcium Channels; C495674:SLC5A1 protein, human; D051269:Sodium-Glucose Transporter 1; D050916:TRPV Cation Channels; C422827:TRPV6 protein, human; D002117:Calcitriol
Glucose-galactose malabsorption; Hypercalcemia ; Nephrocalcinosis