経口ブドウ糖負荷試験 oral glucose tolerance test
出典(authority):フリー百科事典『ウィキペディア(Wikipedia)』「2013/06/20 13:46:14」(JST)
経口ブドウ糖負荷試験(けいこうブドウとうふかしけん、Oral glucose tolerance test, OGTT)は、糖尿病の診断方法のひとつ。糖尿病が疑われる患者に対し、短時間に一定量のブドウ糖水溶液を飲んでもらい、一定時間経過後の血糖値の値から、糖尿病が存在するかどうかを判断する方法である。
現在では、WHOの基準に従い、75gのブドウ糖を負荷し、2時間後の血糖値を測定して診断する。以前は施設により、50gや100gのブドウ糖を用いることがあった。
糖尿病型と判断される基準は、2時間後の血糖値で200mg/dl以上。
血糖値を意図的に上昇させる試験であるため、既に本試験の前に行っている空腹時血糖値や随時血糖値によって糖尿病型と診断されている患者にはこの試験を施行してはならない(禁忌である)とされている。もっともこの検査によって誘発される高血糖は一時的であり、よほどのことがない限りはこの試験で病状を大きく悪化させる心配はないが、血糖値を反映するヘモグロビンA1c(HbA1c)のような便利な検査が普及している日本においては、その適応について、慎重に判断されるべきものである。
A glucose tolerance test is a medical test in which glucose is given and blood samples taken afterward to determine how quickly it is cleared from the blood.[1] The test is usually used to test for diabetes, insulin resistance, and sometimes reactive hypoglycemia and acromegaly, or rarer disorders of carbohydrate metabolism. In the most commonly performed version of the test, an oral glucose tolerance test (OGTT), a standard dose of glucose is ingested by mouth and blood levels are checked two hours later. Many variations of the GTT have been devised over the years for various purposes, with different standard doses of glucose, different routes of administration, different intervals and durations of sampling, and various substances measured in addition to blood glucose.
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Since the 1970s, the World Health Organization and other organizations interested in diabetes agreed on a standard dose and duration.
The patient is instructed not to restrict carbohydrate intake in the days or weeks before the test. The test should not be done during an illness, as results may not reflect the patient's glucose metabolism when healthy. A full adult dose should not be given to a person weighing less 42.6 kg (94 lb), or exaggerated glucoses may produce a false positive result. Usually the OGTT is performed in the morning as glucose tolerance can exhibit a diurnal rhythm with a significant decrease in the afternoon. The patient is instructed to fast (water is allowed) for 8–12 hours prior to the tests.
If renal glycosuria (sugar excreted in the urine despite normal levels in the blood) is suspected, urine samples may also be collected for testing along with the fasting and 2 hour blood tests.
Fasting plasma glucose (measured before the OGTT begins) should be below 6.1 mmol/L (110 mg/dL). Fasting levels between 6.1 and 7.0 mmol/L (110 and 125 mg/dL) are borderline ("impaired fasting glycaemia"), and fasting levels repeatedly at or above 7.0 mmol/L (126 mg/dL) are diagnostic of diabetes.
A 2 hour OGTT glucose level below 7.8 mmol/L (140 mg/dL) is normal, whereas higher glucose levels indicate hyperglycemia. Blood plasma glucose between 7.8 mmol/L (140 mg/dL) and 11.1 mmol/L (200 mg/dL) indicate "impaired glucose tolerance", and levels above 11.1 mmol/L (200 mg/dL) at 2 hours confirms a diagnosis of diabetes.
It is important to stress that the diagnosis criteria stated above by the World Health Organisation (WHO) is for venous samples only i.e. a blood sample taken from a vein in the arm. An increasingly popular method for measuring blood glucose is from a capillary or finger-prick sample. This is less invasive, more convenient for the patient and requires minimal training to conduct. Whilst fasting blood glucose have been shown to be similar in both capillary and venous samples, postprandial blood glucose levels (those measured after a meal) can vary. Therefore the diagnosis criteria issued by the WHO should only be used for venous blood samples. Given the increasing popularity of capillary testing the WHO has recommended that a conversion factor between the two sample types be calculated. To date no conversion factor has been issued by the WHO despite some medical professionals adopting their own.
A standard 2 hour OGTT is sufficient to diagnose or exclude all forms of diabetes mellitus at all but the earliest stages of development. Longer tests have been used for a variety of other purposes, such as detecting reactive hypoglycemia or defining subsets of hypothalamic obesity. Insulin levels are sometimes measured to detect insulin resistance or deficiency.
The OGTT is of limited value in the diagnosis of reactive hypoglycemia, since (1) normal levels do not preclude the diagnosis, (2) abnormal levels do not prove that the patient's other symptoms are related to a demonstrated atypical OGTT, and (3) many people without symptoms of reactive hypoglycemia may have the late low Glucose.
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国試過去問 | 「104B052」「104B050」「104B051」「104G041」「104I076」 |
リンク元 | 「経口ブドウ糖負荷試験」 |
拡張検索 | 「75g OGTT」「75g-OGTT」「75gOGTT」 |
ABE
※国試ナビ4※ [104B051]←[国試_104]→[104B053]
C
※国試ナビ4※ [104B049]←[国試_104]→[104B051]
E
※国試ナビ4※ [104B050]←[国試_104]→[104B052]
BDE
※国試ナビ4※ [104G040]←[国試_104]→[104G042]
B
※国試ナビ4※ [104I075]←[国試_104]→[104I077]
経口ブドウ糖負荷試験 : 約 13,400 件 経口グルコース負荷試験 : 約 6,370 件
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