goljan_fan
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A 34-year-old woman has had severe watery diarrhea for the past four days. Two months earlier she had infectious mononucleosis. She abuses drugs intravenously and has antibodies to HIV in her blood. Physical examination shows dehydration and marked muscle weakness.Laboratory studies are most likely to show
A. decreased serum K+ concentration
B. decreased serum Ca2+ concentration
C. increased serum HCO3- concentration
D. increased serum Na+ concentration
E. increased serum pH
pls explain lab findings in severe diarrhea
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| skyhigh
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in diarrhea there is usually loss of HCO3, so serum HCO3 should decrease.
since there is no ans choice as the above, i would choose A, dec . K+ leading to muscle weakness.
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| doc179
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My answer is A. Diarrhea leads to K+ loss and HCO3- loss.
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| pocas
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 A is the answer
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| goljan_fan
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Correct Ans D.
May be due to Renin-angio-alsosterone axis activn d/t severe diarrhea
In volume-depleted states, GFR and Na delivery to the distal nephron decrease, causing release of renin by the afferent arteriolar cells of the juxtaglomerular apparatus.
Edited by goljan_fan on 01/25/06 - 07:24 PM
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| sarika
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i dont understand these explainations like in this question Ans a can also be justified e.g since its diarrhea their must be increased H in serum and metabolic acidosis .This increased H will exchange with intracellular K leading to decreased K in serum.
Am i wrong here?
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| doc179
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well that is what even I thought of
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| goljan_fan
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w.r.t above Q,In evaluating the cause of the diarrhea, which of thefollowing is most appropriate?
A. Colonic biopsy to identify Giardia lamblia
B. Culture of the oral cavity for Candida albicans
C. Duodenal biopsy to identify Entamoebahistolytica
D. Gastric aspirate to identifyMycobacterium avium-intracellulare
E. Stool specimen to identify Cryptosporidium
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| robin082006
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CRYPTOSPORIDIUM?
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| robin082006
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USUSALLY IN DIARRHEA THERE ARE HYPOKALEMIA AND HYPOBICARBONEMIA
DIARRHEA IS ISOTONIC CONTRACTION, INITIALLY Na is unchanged, low Na occurs only when compensation. But K and HCO3 will decrease firstly
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| doc179
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E?
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| reet
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E... CRYPTOSPORIDIUM diarhoea in AIDS PT.
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| goljan_fan
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YES ,ans is E.
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| reet
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why NOT answer .A..in first ques Why we ignoring Loss of K+..
is that dehydration has bigger effect than K loss.???
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| goljan_fan
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Aswer to first Q,given in source book is D. & THERE IS NO EXPLANATION GIVEN.
Can anybody else explain why correct ans is D. increased serum Na+ concentration
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| drk1980
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goljan_fan wrote:
Aswer to first Q,given in source book is D. & THERE IS NO EXPLANATION GIVEN.
Can anybody else explain why correct ans is D. increased serum Na+ concentration
Wht is ur book source??
After FOUR days of dehydrating watery diarrhea, the renin-ang-aldo system wud hv kicked in...causing inc reabs of Na...hence inc serum Na.
However, the muscle weakness...made me also to think of dec serum K+.
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| humpf!!
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could muscle weakness be attributed to a shift in Ca? Ca and Na move in opposite directions across the cell membrane...sorry, I've always had a hard time with this concept...if in fact the answer is increased Na secondary to the 4 days of dehydration...and Ca and Na move in opp. directions...could that account for the muscle weakness?
I could be totally wrong...please correct!
Edited by humpf!! on 01/27/06 - 09:05 AM
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| humpf!!
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how long does it take for the RAA system to kick in?
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| robin082006
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Hi
I review again about diarrhea in Kaplan,
Kaplan explains that firstly K+ and HCO3- decrease when diarrhea, resulting in metabolic acidosis
Compensation will occur in kidney, H+ and K+ will exchange so K+ returns to normal values
RAA will activate, increased Na+ reabsorption, water reabsorption resulting in hypernatremia. In addition, Water was reabsorted but not completely compensated, therefore blood Na+ increases higher in comparision with blood Na+ increase due to aldosterone's alone effect in normal condition.
RAA activation will result in hypokalemia but because K+ is exchanged with H+ (due to metabolic acidosis), K is normal or slightly low.
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