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Old 03-20-2012
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Urine Sample The likely cause of this hyponatremic seizure?

A 70-year-old patient is brought by ambulance to the emergency department for seizures. On arrival the patient is confused and is judged delirious. His wife arrives soon after and provides a medical history of an unspecified mental disorder treated with thiothixene and hypertension treated with hydrochlorothiazide. Physical examination shows moist mucous membranes and a blood pressure of 130/90 mm Hg with a pulse of 80 beats/minute. No postural hypotension is noted. Electrolyte panel and urinalysis values include serum Na+ 112 mEq/L, serum osmolality 258 mOsm/L, urine Na+ 38 mEq/L, and urine osmolality 410 mOsm/L.
Which of the following is the most likely diagnosis?

A. Acute renal failure
B. Diabetes insipidus
C. Hydrochlorothiazide overdose
D. Hyperthyroidism
E. Syndrome of inappropriate antidiuretic hormone
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E. Syndrome of inappropriate antidiuretic hormone - Normal hydration, high serum osmolarity, low serum Na and high urine Na point towards this diagnosis.
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E
Look at serum Na, serum and urine osmalirty
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Quote:
Originally Posted by Lena View Post
E
Look at serum Na, serum and urine osmalirty
i know normal serum Na and serum osmolarity values.

may i knw what is normal urine na levels?

regarding urine osmolarity, its value can vary ...so how can i say this patient has low urine osmolarity? please help...:sorry:
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Siadh.....
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Quote:
Originally Posted by tyagee View Post
i know normal serum Na and serum osmolarity values.

may i knw what is normal urine na levels?

regarding urine osmolarity, its value can vary ...so how can i say this patient has low urine osmolarity? please help...:sorry:

i think it corelated to plasma osmolarty. when pt is dehydrated urine osmolarty incresed above that of plasma.
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E. Syndrome of inappropriate antidiuretic hormone
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Quote:
Originally Posted by tyagee View Post
i know normal serum Na and serum osmolarity values.

may i knw what is normal urine na levels?

regarding urine osmolarity, its value can vary ...so how can i say this patient has low urine osmolarity? please help...:sorry:
A volume-overloaded patient with low osmolarity should be concentrating their urine to 800 mOsm or greater.

Caveat: in long-standing over-diuresis, medullary solute can get washed out, reducing the kidney's ability to concentrate the urine.

Urine sodium varies with renal status as well as osmolarity and volume status, so there's no real normal... A healthy kidney retaining sodium in the face of volume depletion will generally put out less than 25 mmol/L, but a patient with renal failure can lose some of the ability to reabsorb sodium, which would make that higher :/

It's a weird question, since thiothixene can cause siadh and hctz can cause volume-depleted hyponatremia... bah, too hard!

I suppose that, since mucous membranes are moist and there are no signs of volume depletion that I'd go with SIADH as well...
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Emergency-Medicine, Endocrinology-, Internal-Medicine-, Step-2-Questions

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