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A 7-week-old boy is brought to the physician
because of fever,
irritability, and lethargy for 3 days. He has had no
vomiting,
diarrhea, or symptoms of an upper respiratory tract
infection. He always seems
hungry to his mother despite being fed 3 ounces of
formula every 3
hours. His mother also notes that he has many wet
diapers throughout the
day and night. He currently appears irritable. His
temperature is 37.8
C (100 F), blood pressure is 80/50 mm Hg, pulse is
150/min, and
respirations are 25/min. Examination shows a sunken
anterior fontanelle.
Mucous membranes are dry. There is tenting of the
skin. Examination
shows no other abnormalities. Urinalysis is negative
for glucose and
protein.
Na+(mEq/L) Cl“(mEq/L) K+(mEq/L) HCO3“(mEq/L)
pH Specific
gravity

A
)
132 89 2.8 39 5.0 1.025

B
)
133 110 3.9 16 6.0 1.015

C
)
163 117 4.3 22 5.5 1.003

D
)
165 115 4.5 19 5.0 1.030
these are the urinary values btw.

can someone help me with this one pls?

AAAA
bab;y i s dehyrated
so the urine has to be concentrated
so high specific gravity----so A ro D
now if u have dehydration---what will u do
u will conserve NA AND K AND CL AND WHATEVER U HAVE
SO urine shud have low na and k and cl
so A meets all these criteria

thanks, can you tell me what the reason of this dehydration is?

can u please read the question again
the baby had wet diapers day and night -----as u said in histry
the FONTANELLE ----is sunken,,lethargy,,,baby hungry,,bp--down
what else u need

biochem i bumped this quest up yesterday. didu check that? it has ans.

i m sorry u asked for cause of the dehyration---
may be rota virus

i think i marked A. but in prev post ans was C that i think is wrong.

by this we should go by A. tht looks more logical. thanks to you both. btw cuteangel, this kid doesn't have diarrhea. thts why it got me thinking about DI etc.

biochem if its DI then ans should be B. i dont know why C ?////. C has very high Na , how possible?

A few important things here:
1. Baby is dehydrated but still urinates (this is uncommon kidneys are shut down earlier in babies) so this must be something central DI maybe?
2. Baby is irritable but doesn't have fever (hypernatremia perhaps? yes he's dehydrated and is urinating)
Can't be rotavirus the vignette clearly states no vomiting no diarrhea and if he was dehydrated with diarrhea he shouldn't be urinating right?
3. Dehydrated hmm but BP is normal? Another clue here

The answer is C this is mainly DI and that is why urine is diluted it's the only option that has diluted urine

Good luck
BDJ