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NBME Answers

free120/Block 3/Question#10
A 4-year-old boy is brought to the physician ...
Calcium: decreased;
Inorganic phosphorus: increased;
1,25-dihydroxycholecalciferol: decreased;
Erythropoietin: decreased
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This patient has chronic kidney disease, as indicated by elevated serum creatinine/BUN and evidence of anemia of chronic disease (normochromic normocytic). Poorly functioning kidneys do not hydroxylate 25-dihydroxycholecalciferol to 1,25-dihydroxycholecalciferol well nor produce adequate erythropoietin (hence the CKD-related anemia). Patient’s with CKD thus develop secondary hyperparathyroidism due to deranged phosphate excretion and inadequate Vitamin D activation resulting in hypocalcemia. Thus, we should expect to see low calcium, high phosphorus, low 1,25 vitamin D, and low Epo.

houseppary  Any guesses as to why he might have CKD at 4 y.o.? +1  
drpee  Possibly ARPKD? +  



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