2015 Usmle samples, Q:111

[bcelikten]

A 26-year-old woman is brought to the
emergency department by her mother 1 hour
after she had a generalized tonic-clonic seizure at
home. The mother states that her daughter has
been talking to herself at all hours of the day and
night about being thirsty. The patient was found
to have schizophrenia 6 years ago. Her only
medication is haloperidol. She was admitted to
the hospital twice in the past year for psychotic
episodes. Physical examination shows no other
abnormalities. She is oriented to person but not
to place or time. Her serum sodium
concentration is 114 mEq/L on arrival but
returns to normal with appropriate treatment.
Which of the following interventions is the most
appropriate next step?


(A) Refer the patient for behavior therapy
(B) Restrict the patient's fluid intake
(C) Add lithium carbonate to the medication
regimen
(D) Administer furosemide therapy
(E) Begin mineralocorticoid therapy

answer is b. but I dont understand why we restrict fluid intake. Could someone explain it to me? Thank you

[Khorreed]

Originally Posted by bcelikten

A 26-year-old woman is brought to the
emergency department by her mother 1 hour
after she had a generalized tonic-clonic seizure at
home. The mother states that her daughter has
been talking to herself at all hours of the day and
night about being thirsty. The patient was found
to have schizophrenia 6 years ago. Her only
medication is haloperidol. She was admitted to
the hospital twice in the past year for psychotic
episodes. Physical examination shows no other
abnormalities. She is oriented to person but not
to place or time. Her serum sodium
concentration is 114 mEq/L on arrival but
returns to normal with appropriate treatment.
Which of the following interventions is the most
appropriate next step?


(A) Refer the patient for behavior therapy
(B) Restrict the patient's fluid intake
(C) Add lithium carbonate to the medication
regimen
(D) Administer furosemide therapy
(E) Begin mineralocorticoid therapy

answer is b. but I dont understand why we restrict fluid intake. Could someone explain it to me? Thank you

Kk, first what you need to understand Electrolyte disturbances is to read Acid-Base and Fluids made ridiculously simple

Her serum sodium
concentration is 114 mEq/L(normal 135-140 mEq/L)

Sodium concentration decrease tell us about excessive amount of fluid(because Sodium CONCENTRATION depends ONLY on amount of fluid and not on the total body sodium concentration)
More water - concentration of sodium would be less(hyponatremia)
Less water in blood - concentration of sodium would be more(hypernatremia)
More TOTAL body sodium(concentration*extracellular volume) - edema
Less TOTAL body sodium(concentration*extracellular volume(variable from patient to patient) - dont remember now(maybe collapse?).
So, if there is lowering of sodium concentration - there is excess water
That is why we need to restrict water intake

[med_doc]

Originally Posted by bcelikten

A 26-year-old woman is brought to the
emergency department by her mother 1 hour
after she had a generalized tonic-clonic seizure at
home. The mother states that her daughter has
been talking to herself at all hours of the day and
night about being thirsty. The patient was found
to have schizophrenia 6 years ago. Her only
medication is haloperidol. She was admitted to
the hospital twice in the past year for psychotic
episodes. Physical examination shows no other
abnormalities. She is oriented to person but not
to place or time. Her serum sodium
concentration is 114 mEq/L on arrival but
returns to normal with appropriate treatment.
Which of the following interventions is the most
appropriate next step?


(A) Refer the patient for behavior therapy
(B) Restrict the patient's fluid intake
(C) Add lithium carbonate to the medication
regimen
(D) Administer furosemide therapy
(E) Begin mineralocorticoid therapy

answer is b. but I dont understand why we restrict fluid intake. Could someone explain it to me? Thank you

Haloperidol-induced syndrome of inappropriate secretion of antidiuretic hormone(ADH). Can’t really take off the Haloperidol because “She was admitted to the hospital twice in the past year for psychotic
episodes…She is oriented to person but not
to place or time.” Also half-life of haloperidol is 21-24h. SO water restriction is the only option
The following is the pubmed’s link to the related article
http://www.ncbi.nlm.nih.gov/pubmed/487691

Haloperidol-induced syndrome of inappropriate secretion of antidiuretic hormone(SIADH). Can’t really take off the Haloperidol because “She was admitted to the hospital twice in the past year for psychotic
episodes…She is oriented to person but not
to place or time.” Also half-life of haloperidol is 21-24h. SO h2o restriction is the only option
The following is the pubmed’s link to the related article to make sure that you would never forget about that..
http://www.ncbi.nlm.nih.gov/pubmed/487691