Дискуссионный Клуб Русского Медицинского Сервера
MedNavigator.ru - Поиск и подбор лечения в России и за рубежом
  #1  
Старый 09.07.2012, 23:43
Аватар для Dr.Vad
Dr.Vad Dr.Vad вне форума
Модератор форума по гематологии
      
 
Регистрация: 16.01.2003
Город: Хьюстон, Техас
Сообщений: 77,627
Поблагодарили 31,992 раз(а) за 30,381 сообщений
Dr.Vad этот участник имеет превосходную репутацию на форумеDr.Vad этот участник имеет превосходную репутацию на форумеDr.Vad этот участник имеет превосходную репутацию на форумеDr.Vad этот участник имеет превосходную репутацию на форумеDr.Vad этот участник имеет превосходную репутацию на форумеDr.Vad этот участник имеет превосходную репутацию на форумеDr.Vad этот участник имеет превосходную репутацию на форумеDr.Vad этот участник имеет превосходную репутацию на форумеDr.Vad этот участник имеет превосходную репутацию на форумеDr.Vad этот участник имеет превосходную репутацию на форумеDr.Vad этот участник имеет превосходную репутацию на форуме
Дефицит цинка: публикации и материалы по теме

Zinc deficiency can present in many ways and should be considered in people with at-risk conditions. Aside from the severe rash of acrodermatitis enteropathica seen in profound zinc deficiency, the manifestations of zinc deficiency are protean and non-specific. The diagnosis can be especially elusive because symptoms may overlap with the many conditions that predispose to zinc deficiency. For this reason, a high index of suspicion is critical.

Clinical evaluation

Acquired zinc deficiency may result from poor nutritional intake, ingestion of foods or drugs that reduce zinc absorption, chronic illness, or any combination of these. Symptoms are quite diverse and clinical suspicion for this must be high in at-risk people. Acquired zinc deficiency can be seen in many patient groups. These include patients with malabsorption syndrome, chronic GI and liver disease, diabetes, renal disease, sickle cell disease, anorexia nervosa, and HIV infection; chronic treatment with certain medication (hydrochlorothiazide, penicillamine, ethambutol, certain antibiotics); and patients >65 years. Zinc deficiency may contribute to many of the problems associated with ageing, including susceptibility to infection and osteoporosis. Pica (clay eating) is common in children in some communities. Clay efficiently binds zinc, leading to dramatically decreased bioavailability.

Other risk factors include alcoholism, vegetarianism or veganism, and living in a developing region:

Alcoholics tend to be deficient in zinc, along with a variety of other nutrients

Low meat intake or high phytate/oxalate intake can contribute to zinc deficiency. Phytates and oxalates are found in many grain and vegetable products including soy, bran, whole grains, spinach, berries, chocolate, and tea. This is compounded by the tendency of diets low in meat to be high in the fibrous plant products that bind zinc, further limiting absorption.

Zinc is a key micronutrient important in growth and development, immune function, taste, smell, wound healing, protein synthesis, and maintenance of skin and hair. Some clinical features affected by zinc deficiency include:

Growth and development: growth retardation, hypogonadism, osteopenia (increased risk of bone fracture), weight loss

Neurological: intention tremor, depression, impaired concentration, nystagmus, dysarthria, night blindness, hypogeusia, anosmia, dementia

Dermatological: alopecia, dermatitis, paronychia, stomatitis

Gastrointestinal: anorexia, abdominal pain, diarrhoea, glossitis

Miscellaneous: fatigue, delayed wound healing, fever, pica, increased infections, blepharitis, impaired glucose tolerance, infertility/adverse pregnancy outcomes.

Symptoms may overlap with the many conditions that predispose to zinc deficiency. Because there is such a non-specific presentation of zinc deficiency, it may be clinically difficult to differentiate it from from hypothyroidism and depression; other nutrient deficiencies that may co-exist with cases of zinc deficiency, including iron, vitamin D, vitamin A, vitamin B12, and folate, may also be difficult to differentiate. These deficiencies should be considered and tested for appropriately.

Acrodermatitis enteropathica is a manifestation of severe zinc deficiency typically caused by an autosomal-recessive disease, through impaired absorption. This disorder typically presents in infancy with crusting, vesicular dermatitis, View imageView image diarrhoea, growth retardation, and infections. However, acrodermatitis enteropathica may also rarely occur in adults with severe nutritional deficiency.

Laboratory tests
If zinc deficiency is suspected, serum or plasma zinc testing should be done. Serum and plasma zinc levels are most commonly used and are the only tests available in routine clinical practice. Data support the use of either <9.2 micromols/L (60 micrograms/dL) or <10.7 micromols/L (70 micrograms/dL) as abnormal in non-pregnant adults. Owing to the relatively low sensitivity of serum zinc levels in marginal deficiency, oral supplementation should be considered if symptoms are typical, even if test results are normal.

Other nutrient deficiencies often co-exist with zinc deficiency. Deficiencies in iron, vitamin D, vitamin B12, and folate should be tested for. Deficiencies of other fat-soluble vitamins are relatively rare and hard to measure and thus, are not commonly tested.

In cases where zinc deficiency is due to dietary factors, no further evaluation is generally necessary. Evaluation for occult GI disease such as c0eliac disease or Crohn's disease is warranted if zinc deficiency is found in an individual without known risk factors.

Cell zinc content and analysis of zinc levels in hair are two emerging tests.

Cell zinc content: because 95% of zinc is intracellular, zinc levels in a variety of cell populations (red blood cells, platelets, white blood cells) have been evaluated in research settings. Although cellular zinc levels fluctuate less than serum, they are technically more difficult than serum- or plasma-based tests, and superiority has not been clearly demonstrated.

Analysis of zinc levels in hair: the utility of hair zinc analysis is unclear, and has been used primarily in research settings.

([Ссылки доступны только зарегистрированным пользователям ])
__________________
Искренне,
Вадим Валерьевич.
 


Опции темы Поиск в этой теме
Поиск в этой теме:

Расширенный поиск
Опции просмотра

Ваши права в разделе
Вы не можете создавать темы
Вы не можете отвечать на сообщения
Вы не можете прикреплять файлы
Вы не можете редактировать сообщения

BB коды Вкл.
Смайлы Вкл.
[IMG] код Вкл.
HTML код Выкл.



Часовой пояс GMT +3, время: 11:13.




Работает на vBulletin® версия 3.
Copyright ©2000 - 2023, Jelsoft Enterprises Ltd.