推 kuanda:感謝大大無私分享 科科 08/04 14:00
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→ bathape:第一次看到 N Engl J Med 這幾個字覺得心安的 08/04 15:46
※ 引述《SkySlaughter (※天空屠殺者※)》之銘言：
: 孕婦若在懷孕期間服用過量維生素A便容易導致畸胎的發生，包括胎兒的臉部畸形、腦水
: 腫、視神經病變、唇顎裂、先天性心臟病、腦神經機能障礙、發育遲緩等問題，因此孕
: 婦在攝取任何營養劑或食物時，要注意是否含有過高的維生素A，或是攝取的量適不適
: 當，以免讓自己的寶寶遭受傷害。
: 以上所述 幾乎每個選項都可以選
: 而且題幹是問"可能"有關
: 建議更正後答案為(A)(B)(C)(D)
: 附議者請推一下文謝謝
William obsterics, 23ed
Vitamin A
There are two natural forms of vitamin A. Beta-carotene is a precursor of
provitamin A. It is found in fruits and vegetables and has never been shown
to cause birth defects (Oakley and Erickson, 1995). Retinol is preformed
vitamin A. Many foods contain vitamin A, but animal liver contains the most.
Several reports of prenatal supplementation have associated high doses of
vitamin A with congenital anomalies. However, they were clouded by small
numbers, unknown daily dose, and absence of any recognizable pattern of
observed defects. Two cohort studies have also been inconclusive (Conway,
1958; Rothman and co-workers, 1995). The only prospective study included 423
women who contacted European Teratology Services to report exposure
(Mastroiacovo and associates, 1999). These women had ingested from 10,000 to
300,000 IU of vitamin A daily during the first 9 weeks of pregnancy. Only
three exposed newborns had birth defects, and there was no relationship
between vitamin dose and outcome. It seems reasonable to avoid doses higher
than the recommended daily allowance of 5000 IU (American College of
Obstetricians and Gynecologists, 1995). Nohynek and colleagues (2006) found
that human topical exposure to retinol- or retinyl ester-containing cosmetic
creams at 30,000 IU/day did not affect plasma levels of retinol, retinyl
esters, or retinoic acids.
題幹只寫了Vitamin A，但是William's裡面寫的Vitamin A根本沒有造成畸胎的evidence
另外後面有提到
Isotretinoin is considered one of the most potent teratogens in common use.
Etretinate is associated with severe anomalies similar to those with
isotretinoin
但這些都是口服跟外用的retinoids
所以看來可以建議全部送分呢(笑)
另外再附上另外一本寫的
Gabbe: Obstetrics: Normal and Problem Pregnancies, 5th ed.
Vitamin A
There is no evidence that vitamin A itself in normal doses is teratogenic,
nor is betacarotene. The levels in prenatal vitamins (5,000 IU/day orally)
have not been associated with any documented risk. Eighteen cases of birth
defects have been reported after exposure to levels of 25,000 IU of vitamin A
or greater during pregnancy. Vitamin A in doses greater than 10,000 IU/day
was shown to increase the risk of malformations in one study but not in
another.
它支持高劑量vitamin K會致畸胎的reference是這篇
Teratogenicity of High Vitamin A Intake
N Engl J Med 1995; 333:1369-1373
http://www.nejm.org/doi/full/10.1056/NEJM199511233332101#articleTop
而且裡面提到佔比例最高的畸胎其實是cranial-neural-crest origin
也不是答案選的limb malformation
搞了半天還是搞不懂出題老師的reference從哪來的....
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※ 編輯: Dilberth 來自: 211.74.211.22 (08/04 14:19)