d****y
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zhu84518 (lot) 于 (Wed Aug 8 22:41:34 2012, 美东) 提到:
A previously healthy 32-year-old woman who works as a nurse comes to the
emergency department because of a 3-week history of episodes of dizziness,
nausea, and profuse sweating that resolve with eating. She does not smoke.
She drinks four glasses of wine weekly. Vital signs are within normal limits
. Physical examination shows no abnormalities. While in the emergency
department, she becomes dizzy and diaphoretic; and her serum glucose
concentration is 45 mg/dL. Laboratory studies obtained during the episode
show:
请问诊断是什么？
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zhanghaowei4 (flyingtiger4) 于 (Wed Aug 8 22:53:23 2012, 美东) 提到:
Look like a insulinoma.
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zhu84518 (lot) 于 (Wed Aug 8 23:14:11 2012, 美东) 提到:
感谢感谢，How to explain the normal level of insulin?
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zhanghaowei4 (flyingtiger4) 于 (Wed Aug 8 23:53:32 2012, 美东) 提到:
En...it is upper limit... Look at C peptide.
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zhu84518 (lot) 于 (Thu Aug 9 10:36:49 2012, 美东) 提到:
Thanks, the level of insulin is varying or constant?
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JennyGao424 (Jenny) 于 (Thu Aug 9 13:32:56 2012, 美东) 提到:
The level of insulin should be inversely correlates with blood glucose level
. The fact that at the very low level of Glucose (35mg/ml), the insulin
level of nearly upper limit is absolutely abnormal.
Since the patient is a nurse, it also need to exclude the possibility of
self-administration of insulin.
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hmis (hmis) 于 (Fri Aug 10 14:00:25 2012, 美东) 提到:
Should be E.
I do not think this is insulinoma b/c c- peptid and insulin are both normal.
This patient has several hypoglycemia. It can be from Addision's disease.
And for Addision's disease , common from pituitary disease.
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JennyGao424 (Jenny) 于 (Fri Aug 10 17:28:50 2012, 美东) 提到:
hmis,
First, the cortisol level is normal here, which is inconsistent with Addison
's disease. Moreover, the cardinal signs and symptoms of Addision's disease,
hypotension, hyponatriemia, hyperkalemia and darkened skin are not
reflected in this patient. Last, there seems no pituitary tumor that could
suppress production of aldosterone or cortisol.
Thanks for discussing it.
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hmis (hmis) 于 (Fri Aug 10 19:32:24 2012, 美东) 提到:
You r right, however what u discribed is primary Addision's disease. If I
mean primary Addision's, the patient should have high pigmentation which
means low cortisol high ACTH. Obviously not this case. That is why we won't
go to answer A.
Then, u can think may secondary Addision's disease. That is the disease of
pituitary. Then low ACTH , low Cortisol. Patient won't have high
pigmentation due to low ACTH . Right?
Usuarally, in an emergency situation, cortisol ,as a very important hormone,
should rise up. Look at this patient , only at low normal. I felt it is not
normal sign.
This is one reason.
Second reason, low cortisol can severely icrease insulin sensitivity. That
can be the other reason.
What do u think?
Addison
disease,
could
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qdmd (tube.washer) 于 (Fri Aug 10 20:12:24 2012, 美东) 提到:
这道题要是有外源胰岛素注射选项就完美了，可惜没有。 pituitary gland can not
explain anything in this question.
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hmis (hmis) 于 (Fri Aug 10 20:33:07 2012, 美东) 提到:
Why? Give a reason? Why not pituitary gland explain it?
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qdmd (tube.washer) 于 (Fri Aug 10 20:53:44 2012, 美东) 提到:
hmis是高手，这次读题不仔细了。智者千虑，偶有一失。
A previously healthy 32-year-old woman nurse ， a 3-week history of
episodes of dizziness,
nausea, and profuse sweating that resolve with eating.. Vital signs are
within normal limits
. Physical examination shows no abnormalities. and her serum glucose
concentration is 45 mg/dL.
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hmis (hmis) 于 (Fri Aug 10 21:25:37 2012, 美东) 提到:
不是高手，只是我一直在内分泌做见习。所以感兴趣。聊聊呗。当然，医护人员首选考
虑滥用药物。 不过这道题，我反而觉得给护士是迷糊大家的。usmle考的还是基本概念
。交流交流。。。
带我见习的老教授和我讨论了一下这个题。 顺便介绍了一下我们这个论坛
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qdmd (tube.washer) 于 (Fri Aug 10 22:03:15 2012, 美东) 提到:
用最简单的单一疾病做诊断。hmis老师说的很深奥，途径从头到腰。的确，pituitary
gland problem can explain part of this patient's low glucose level, however,
pituitary gland problem will also cause adrenal cortex a series of changes
which never showed up in this patient.
As a physician, it is not correct to use a very complicated and rare disease
to explain only part of the whole picture.
这个题，C-peptide level 低，是唯一不完满的地方，但是用胰岛素瘤能解释的通，脉
冲释放。
hmis其他的解释的很好受教了。
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hmis (hmis) 于 (Fri Aug 10 22:17:51 2012, 美东) 提到:
Nice, let me keep this q and send out to another professor. C what does she
think? Then we can learn more...haha I like this discussion. Very nice!
Thanks, enjoy
pituitary
however,
changes
disease
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JennyGao424 (Jenny) 于 (Fri Aug 10 23:51:40 2012, 美东) 提到:
Thank great discussion from both of you. hmis, I agree with you on most of
thing. But the question ask here is " what tumor" is most likely. Can you
think of a pituitary tumor that reduce level of ACTH?
I think what the question here limited a lot of possibilities.. and in
reality, there are more scenario...
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zhanghaowei4 (flyingtiger4) 于 (Sat Aug 11 00:04:12 2012, 美东) 提到:
Pure assumption:
C-peptide level can only be released by normal "islet cells". Insulinoma
does not contain normal "islet cells" which could not efficiently cleave pro
-insulin peptide to Cpeptide. Waiting for more evidence.
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JennyGao424 (Jenny) 于 (Sat Aug 11 00:30:54 2012, 美东) 提到:
Zhanghaowei4,
You are right! Insulinoma could have much higher proinsulin rather than
mature insulin, which might explain the borderline level of both insulin and
c-peptide level.
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hmis (hmis) 于 (Sat Aug 11 06:13:13 2012, 美东) 提到:
non functional adenoma? I saw several cases in our hospital. It won't
directly reduce the hormone level itself. However , will effect the normal
tissue function
of
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hmis (hmis) 于 (Sat Aug 11 06:16:29 2012, 美东) 提到:
Do u have any paper to support your assumption? I could not find to support
this hypothesis.
If like you said, then it will be very confused Between insulinoma And
exagenous insulin abuse.
pro
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JennyGao424 (Jenny) 于 (Sat Aug 11 11:51:02 2012, 美东) 提到:
http://www.ncbi.nlm.nih.gov/pubmed/15473873
http://www.springerlink.com/content/t315109v8vmn1754/
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JennyGao424 (Jenny) 于 (Sat Aug 11 12:22:01 2012, 美东) 提到:
hmis, thanks for your very informative posts. Have a nice weekend.
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bythesea (沉默是金) 于 (Sat Aug 11 21:12:53 2012, 美东) 提到:
Failure of endogenous insulin secretion to be suppressed by hypoglycemia is
the hallmark of an insulinoma. Thus, the finding of inappropriately elevated
levels of insulin in the face of hypoglycemia is the key to diagnosis. A
plasma insulin concentration of >3 microU/mL (20.8 pmol/L) when the plasma
glucose concentration is below 55 mg/dL (3.0 mmol/L) indicates an excess of
insulin and is consistent with insulinoma.
Plasma C-peptide distinguishes endogenous from exogenous hyperinsulinemia.
In patients in whom plasma glucose concentrations fell below 45 mg/dL (2.5
mmol/L), there was no much overlap in the values in insulinoma patients and
normal subjects at a plasma C-peptide concentration of 0.2 nmol/L (0.6 ng/mL
). All insulinoma patients had higher values and all normal subjects who
were hypoglycemic had lower values.
For plasma proinsulin, the diagnostic criterion for insulinoma is 5 pmol/L
or greater.
Given that this patient has Whipple’s triad, inappropriately elevated
levels of insulin during hypoglycemic attack, urine sulfonylurea negative,
insulinoma is the most likely diagnosis. Work up including a 72-hour fast
test to provoke hypoglycemia, measuring plasma glucose, insulin, C-peptide,
proinsulin at same time when glucose concentration is below 55 mg/dL.
Need to rule out MEN1 syndrome.
Other DD:
1. Insulin autoimmune hypoglycemia
2. Noninsulinoma pancreatogenous hypoglycemia syndrome (NIPHS) caused by
islet hypertrophy and nesidioblastosis. An unusual feature of this disorder
is that hypoglycemia occurs postprandially, two to four hours after a meal.
Fasting hypoglycemia, characteristic of insulinoma, is rare in this
disorder
3. Nonislet cell tumor-induced hypoglycemia: increased production of
IGFII
4. Persistent hyperinsulinemic hypoglycemia of infancy.
http://emedicine.medscape.com/article/283039-workup#a0719
Patients with chronic adrenal insufficiency usually have symptoms such as
weakness, fatigue, poor appetite, and weight loss, orthostatic hypotension,
reduced libido/ amenorrhea (2nd), hypoglycemic episodes due to an increase
in
insulin sensitivity. In addition, this patient’s cortisol level was still
within normal range.
level
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JennyGao424 (Jenny) 于 (Sun Aug 12 00:08:59 2012, 美东) 提到:
bythesea,
受教了， 谢谢！
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skyscorpio (天之蝎子) 于 (Sun Aug 12 00:47:45 2012, 美东) 提到:
大家懂太多了，所以喜欢联想翩翩。象我看一眼题就只能想起一个诊断，就是
insulinoma,然后毫不犹豫地选胰腺，再不会去看它一眼 LOL
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zhanghaowei4 (flyingtiger4) 于 (Sun Aug 12 00:57:49 2012, 美东) 提到:
I would prefer exogenous insulin abuse. But there are no options like that.
I have no idea why C peptide is so low though. Haha..lab technique errors?
support
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skyscorpio (天之蝎子) 于 (Sun Aug 12 00:59:33 2012, 美东) 提到:
LOL when I saw "nurse" I also jumped to find malingering/factitious..
.
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skyscorpio (天之蝎子) 于 (Sun Aug 12 01:04:58 2012, 美东) 提到:
low C-peptide makes C not a perfect answer. but pancreas is the MOST LIKELY
to me.
too little information is provided to make a Dx of Addison's disease...and
how can you tell whether it is due to pituitary or adrenal...
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Dreadnaught (无畏) 于 (Sun Aug 12 02:59:10 2012, 美东) 提到:
I agree with hmis! First, the low limit of C peptide level together with a
high limit insulin level rules out insulinoma. This is because C peptide is
cleaved from proinsulin together with insulin and thus it should be always
parallel to the insulin level. Second, I think the possibility of pituitary
disease is the low level of cortisol. In hypoglycemia condition, cortisol
should be increased as response to stress. But cortisol in this patient is
still in low limit, indicating a failure to response! Pituitary is in a
lower than normal function to release enough ACTH to stimulate cortisol
production. But I have difficulty to find out what exact disease it might be
if hypopituitarism can not be sold.So, ACTH level or cosyntropin test will
be the best way to make it more clear.
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hmis (hmis) 于 (Sun Aug 12 06:07:58 2012, 美东) 提到:
Because we have two adrenal glands and one pituitary. That why secondary is
more common than primary addision?
LIKELY
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bythesea (沉默是金) 于 (Sun Aug 12 09:19:34 2012, 美东) 提到:
呵呵，我赞同你和qdmd的意见，毛病犯了抄书而已。
正常值可能只是在正常情况下的正常人群中的一个%区间。考试大都不会考虑测量误差
，但实际中，可能也是有误差的。 所以要重复测一下C-peptide。 如果没有相
对胰岛素过高的情况下，cortisol相对低也可以考虑一下。如果有胰岛素对血糖比值过
高，还是直接选胰腺吧。 后者可能性小。
对此题来说，猜测，外源性insulin是最大的混淆项，所以考题很直接的避开了，不要
说放入混淆选项，问都不敢问。 出题的人也难啊。 同样的题干，加减一下病史，换个
问题问，就是别的诊断和答案了。 难怪总说题很熟悉，护士/PA职业经常打酱油出现。。
。出题的人也懒啊。
所以考试就是考试，来源于生活，简单于生活，参照250（分）蝎子就行了。
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daisyy (daisy) 于 (Sun Aug 12 12:01:39 2012, 美东) 提到:
Same here. If it's exogenous insulin abuse, then Insulin is high, but c-
peptide would be low.
.
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daisyy (daisy) 于 (Sun Aug 12 12:13:44 2012, 美东) 提到:
说得很好！
pituitary
however,
changes
disease |
|
