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Old 03-06-2013
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Question Why this hyponatremia?

A 17 year old girl comes to the physician because of fatigue, increased thirst, and increased urination over the past 2 weeks. She has had a 4.5 kg (10 lb) weight loss during this period despite an increased appetite. She has not had dysuria. At the onset of her symptoms, she had a mild upper respiratory tract infection that resolved without treatment. Her temperature is 36.8 deg C (98.2 deg F), pulse is 86/min, respirations are 14/min, and blood pressure is 100/50 mm Hg. Cranial nerves are intact. Muscle strength is 5/5, and deep tendon reflexes are symmetric. Serum studies show: Na+ is 132, Cl- is 96, K+ is 3.7, HCO3- is 26, and Creatinine is 1.2. Which of the following is the most likely location of the primary disease process?

A) Adrenal gland
B) Bone marrow
D) Kidney
E) Liver
F) Muscle
G) Pancreas
H) Parathyroid gland
I) Pituitary gland
J) Thyroid gland

I won't say the answer now, but someone told me that its a case of spurious hyponatremia. Can anyone explain why is it so?
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a_usmle (12-23-2013)

Old 12-23-2013
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Can you expain the answer

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Old 12-23-2013
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DM1... with pseudonatrimia
Work Smarter...not harder.
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Old 12-23-2013
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why not D kidney defect???
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Old 12-25-2013
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this is more about you remembering the association between "Viral URI" causing cases of DM1 as well....plus the picture perfect polydipsia, polyuria (osmotic diuresis), polyphagia and losing weight due to lipolysis....

remember autoimmune beta cell destruction (hypoparathyroid may also give Antibodies to insulin but not in this particular case) = no insulin production = hyperglycemia which in turn causes slight hypoNa+ (pseudohypoNa+)

***remember as glucose increases by 100 points Na decreases by 1.6 pts***

again there are numerous factors which can influence Na+ theres a really good algorithm in FA step 2 CK which should help
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Electrolytes-, Endocrinology-, Step-2-Questions

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