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25-year-old white woman comes to your office today to meet you for the first time.
Her only complaint is of headaches. Her blood pressure is 160/105 mm Hg in both arms. She is obese and otherwise has a normal physical examination with no bruits in her abdomen. Two weeks and three weeks later, her blood pressure remains elevated at 155/107 and 157/105 mm Hg, respectively. She smokes but does not drink alcohol. Laboratory studies show: Sodium 138 mEq/L, potassium 4.7 mEq/dL, BUN 14 mg/dL, creatinine 0.8 mg/dL. Urinalysis reveals +1 protein, with no red or white cells. What is the next step to confirm a diagnosis?
(A) Doppler (duplex) ultrasound of the kidneys
(B) Start lisinopril
© Magnetic resonance imaging (MRI) of the abdomen
(D) Captopril renography
(E) Angiography
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The stenosis must have caused an increase in renin-angio-aldosterone no matter it is unilateral or bilateral. Therefore, even though BUN/Cr is normal, Na+ and K+ most likely not normal, and that is the cause of high BP!
In this pt, Na+ and K+ are nornal. The fact that Sodium 138 mEq/L, potassium 4.7 mEq/dL, BUN 14 mg/dL, creatinine 0.8 mg/dL all normal limit exclude the renal artery stenosis, which can activate renin-angio-aldosterone-->high Na, low K+. choice D and E are excluded.
B is about Rx not confirm Dx.
second: The answer said captopril renography is because they regard renal stenosis as the most common cause of secondary HTN. However, renal parenchymal disease is the most common cause of secondary HTN.
In summary, MRI will identify the parenchymal disease which is both the most common cause of HTN and with normal electrolytes. this can also explain the headache, which could be ass. with Polycystic kidney.
I still go with MRI.
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Hi, Dr. S. semi, job, 2ndtime, or anyone on the forum, Could you please give your opinion on this question? I don't think we should assue the answer is correct. occasionaly, it could be wrong.
Let me give you an example:
When I was doing CK, there is a Q on UW saying young woman having acute abdomen. Hx and PE suggested peptic ulcer perforation. They asked for the next step. I chose b-hCG while the original answer said abdominal X-ray. I disagreed with this answer and I wrote to UW inquring about this question. A few days later, the answer was changed to b-hCG. Any child-bearing woman should have pregnancy test before undergo abdominal radiatory test/therapy.
Please let's discuss more of this question and get the right answer. Thank you.
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i think they by mistake give normal Na and K level. in case if they change values to abnormal then answer will be correct?
this is what i think?
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Here is an article buddy.
In unilateral RAS (2K-1C model), renal perfusion pressure is decreased in the kidney distal
to the stenosis, which leads to increased renin production, which in turn forms angiotensin II
(AT II). AT II causes vasoconstriction directly and also stimulates aldosterone production,
which causes salt and water retention. The normal contralateral kidney undergoes a
pressure natriuresis, which maintains volume status. Due to the constantly elevated levels of
renin in the 2K-1C model, this form of RAS is referred to as renin-mediated hypertension.
On the other hand, in the 2K-2C or 1K-1C models representing bilateral RAS or RAS to a
solitary kidney, there is an initial increase in renin, which in turn causes an increase in AT II
and aldosterone. As in the model described, resultant salt and water retention occurs, but
the absence of a normal contralateral kidney prevents pressure natriuresis. Suppression of
renin occurs due to volume expansion attributed to the increases in salt and water retention.
This form of hypertension is considered volume mediated, whereas the 2K-1C model of
unilateral RAS is renin mediated.
What I understand is that when one kidney is still functioning, because of naturesis, it will prevent electrolyte adnormalitis. When both are defected, there is no volume naturesis so you see abnormal BMP.
Abscence of bruit does not r/o renal artery stenosis.
I hope this helps.
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THANK YOU, 2ndtime.
Why can't this case be renal parenchymal disease, such as polycystic kidney? This pt's only complain is headache+HTN.
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for polycyctic disease, I think we do a CT first and see the cysts. I don't know if we jump to MRI to diagnose cyctic disease. Also look at the rest of the choices. Almost all are used to detect vascular defect. I picked treatment because literature says the first step is always to see reponse to treatment. But a renal scan is ok too if they are asking about diagnostic test.
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