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NBME 22 Answers

nbme22/Block 3/Question#42

A 62-year-old man comes to the physician for a ...

Inorganic phosphorus: increased;
Parathyroid hormone: increased;
Calcitriol: decreased


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 +5  upvote downvote
submitted by bubbles(27),

Chronic renal insufficiency:

1) poor phosphate clearance --> high serum inorganic phosphorous

2) high serum phosphate --> complexes with divalent cation Ca --> Ca falls

3) Ca falls --> triggers PTH axis

4) kidney failure --> decreased activity of 1-hydroxylase at the kidney --> less calcitriol





 -4  upvote downvote
submitted by sne(9),

Since she has celiac spruce --> fat vitamin malabsorption, thus Vit. D is decreased Low vit. D = low calcitriol, low absorption of phosphate from intestine, and low absorption of Ca2+ causing an increase PTH