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threewalkers
Forum Junior Topics: 250 Posts: 871 |
A 57-year-old male is hospitalized for hyponatremia. Physical examination reveals no signs of fluid overload. Serum analysis reveals a sodium concentration of 125 mEq/l, glucose level of 128 mg/dl, BUN of 8 mg/dl, and creatinine of 0.7 mg/dl. The urine osmolarity is 330 mOsm/l and urine sodium concentration is 45 mEq/l. After a 2L normal saline infusion, the serum sodium is 126 mEq/l and the urine sodium excretion is increased to 90 mEq/l. Which of the following is the most likely cause of this patient’s hyponatremia? A ). Inappropriate ADH secretion B ). Psychogenic polydipsia C ). Surreptitious diuretic use D ). Advanced liver disease E ). Interstitial renal disease
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threewalkers
| Forum Junior Topics: 250 Posts: 871
How to explain: " After a 2L normal saline infusion, the serum sodium is 126 mEq/l and the urine sodium excretion is increased to 90 mEq/l." Now we are volume overload the pt by giving 2L fluid.
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crazy_girl
| all steps DIED !  Topics: 17 Posts: 525
looks like SIADH ? he has low serum osmolarity (aprox 260 ) and too much Na in urine and urine osm is >> serum osm he retains water after receiving normal saline, his serum Na will be approx the same, which also looks like SIADH
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crazy_girl
| all steps DIED ! Topics: 17 Posts: 525
Fred mon cher, the step 1 fanatics are also preparing for CK.... or step 3  
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crazy_girl
| all steps DIED ! Topics: 17 Posts: 525
mais non!!!!! one at a time , small steps !!!! and this is very very good Q for step 1 and for internal med thank u fred and threewalkers, keep posting guys !
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sidiyaa
| Forum Newbie Topics: 2 Posts: 106
I THINK SIMPELY IT IS E ). Interstitial renal disease . DEFECT IN THE ABSORPTION OF NA. - Physical examination reveals no signs of fluid overload : EXCLUDING SIADH . - GIVING 2 L OF NORMAL SALINE WHICH ISOTONIC IF IT IS SIADH ?WILL FURTER DILUTING NA CONCENTRATION .
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| Topics: Posts:
Fred33 wrote: Initially, low plasma sodium + high urine osmolality + high urine sodium: SIADH; Give 2L normal saline. The ADH gets rid of the water. The initially increased volume reduces aldosterone: increased Na excretion. For a real explanation ask one of our step 1 fanatics who litter our side of the website with depressing questions   > For a real explanation ask one of our step 1 fanatics who litter our side of the website with depressing > I am preparing for Step 1 but it's a good idea to test my clinical knowledge for Step 2 and as you can see without reviewing step 2 I am doing pretty good on my answers. Thanks for the support folks!
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threewalkers
| Forum Junior Topics: 250 Posts: 871
lots of discussion here. The thing I can't explain is why urine Na increase to 90 after 0.9% saline. Na=40 is already high before 0.9% saline.
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threewalkers
| Forum Junior Topics: 250 Posts: 871
what would diuretic (loop or HCTZ) do on serum and urine Na? serum: hypoNa, urine: Na up. So diuretic mimic SIADH. How to tell them apart (besides volume load)?
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.Mia.
| _________  Topics: 29 Posts: 502
Why it can not be C ? Like thiazides cause hyponatremia and hyperglycemia ( his is 128 ). Did anybody think about that ? Threewalkers, what the question answer is in Qbank ? Nice Q.
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.Mia.
| _________ Topics: 29 Posts: 502
threewalkers wrote: lots of discussion here. The thing I can't explain is why urine Na increase to 90 after 0.9% saline. Na=40 is already high before 0.9% saline. Maybe bc of those thiazides ? They are natriuretic. How would you exlain glucose of 128 ? To me it is only one correct answer C. Really currious about explanation.
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crazy_girl
| all steps DIED ! Topics: 17 Posts: 525
i think that 2 L received --> atrial stretch --> natriuretic peptide secretion --> stimulates Na elimination and inhibits RAA/aldosterone.
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threewalkers
| Forum Junior Topics: 250 Posts: 871
answer is A. explanation by uw: Given that the urine osmolarity is increased and greater than the serum osmolarity, the syndrome of inappropriate antidiuretic hormone secretion (SIADH) is the most appropriate diagnosis. They didn't say why "After a 2L normal saline infusion, the urine sodium excretion is increased to 90 mEq/l" I think Even if in SIADH, the urine Na should not increase that much from 45 to 90 after 0.9% Na.
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