乳糖耐受性试验

定义

乳糖耐受性试验 measure the ability of your intestines to break down a type of sugar called lactose. This sugar is found in milk and other dairy products. If your body cannot break down this sugar, you are said to have 乳糖不耐受. This can cause gassiness, abdominal pain, cramps, and diarrhea.

选择的名字

氢气呼吸试验 for lactose tolerance

如何执行测试

两种常见的方法包括：

• 乳糖耐受性血检
• 氢气呼吸试验

The hydrogen breath test is the preferred method. It measures the amount of hydrogen in the air you breathe out.

• You will be asked to breathe into a balloon-type container.
• You will then drink a flavored liquid containing lactose.
• Samples of your breath are taken at set times and the hydrogen level is checked.
• Normally, very little hydrogen is in your breath. But if your body has trouble breaking down and absorbing lactose, breath hydrogen levels increase.

The lactose tolerance blood test looks for glucose in your blood. Your body creates glucose when lactose breaks down.

• 对于这个测试, several blood samples will be taken before and after you drink a liquid containing lactose.
• A blood sample will be taken from a vein in your arm (静脉穿刺).

如何准备考试

You should not eat or do heavy exercise for 8 hours before the test.

考试的感觉如何

There should not be any pain or discomfort when giving a breath sample.

When the needle is inserted to draw blood, 有些人感到轻微的疼痛, while others feel only a prick or stinging feeling. Afterward, there may be some throbbing.

为什么要进行测试

Your health care provider may order these tests if you have signs of 乳糖不耐受.

正常的结果

The breath test is considered normal if the increase in hydrogen is less than 20 parts per million (ppm) over your fasting (pre-test) level.

The blood test is considered normal if your glucose level rises more than 30 mg/dL (1.6 mmol/L) within 2 hours of drinking the lactose solution. 20 ~ 30毫克/分升(1.1 to 1.6 mmol/L)尚无定论.

Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

The examples above show the common measurements for results for these tests. Some labs use different measurements or may test different samples.

异常结果意味着什么

Abnormal results may be a sign of 乳糖不耐受.

A breath test result that shows a rise in hydrogen content of 20 ppm over your pre-test level is considered a positive test. This means you may have trouble breaking down lactose.

The blood test is considered abnormal if your glucose level rises less than 20 mg/dL (1.1 mmol/L) within 2 hours of drinking the lactose solution.

An abnormal test should be followed by a 葡萄糖耐量试验. This will rule out a problem with the body's ability to absorb glucose.

风险

There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight, but may include:

• 昏厥或感到头晕
• Multiple punctures to locate veins
• Hematoma (blood buildup under the skin)
• 大出血
• Infection (a slight risk any time the skin is broken)

参考文献

Floch MH. Lactose, fructose, and sucrose intolerance. 编辑：Floch MH. 网友的胃肠病学. 3日艾德. Philadelphia, PA: Elsevier; 2020:chap 63.

Höegenauer C, Hammer HF. 消化不良和吸收不良. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 11日艾德. Philadelphia, PA: Elsevier; 2021:chap 104.

Siddiqi HA, Rabinowitz S, Axiotis CA. Laboratory diagnosis of gastrointestinal and pancreatic disorders. 见：McPherson RA， Pincus MR，编辑. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24日艾德. Philadelphia, PA : Elsevier; 2022:chap 23.