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How Do I Test Leptin Levels?

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  • Written By: Helga George
  • Edited By: Allegra J. Lingo
  • Last Modified Date: 07 July 2014
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Leptin is a hormone produced by fat cells that signals the brain when the body is satiated with food. Ideally, leptin levels should be low when measured in the morning. Obese people almost always have high levels of the molecule, but their brains do not recognize its signal to feel full and stop eating.

This compound was originally discovered in highly obese mice. Study of their genetics found an obese gene, whose product did not function in these mice. Leptin was then identified as the compound that was missing in these mutants. When the mice were treated with this molecule, they lost weight. This finding provided the basis for a number of weight loss studies to see if treatment with this compound could help people to take off weight.

To provide sample to test for leptin levels, blood is drawn first thing in the morning while fasting. The blood can be stored safely for seven days if refrigerated or two months if frozen. Aside from being tested by medical doctors, blood can be sent to commercial companies to have this test performed.

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Leptin levels are tested by a sensitive process called an ELISA test. Antibodies to the hormone are coupled with an enzyme that will change color if leptin is present in the blood being tested. It is possible to determine the precise amount of the compound being measured with this process. The leptin levels in women range from 3.9 to 30 ng/ml of blood, while those of men are lower at 0.5-12.7 ng/ml.

One of several things this hormone does in mammalian metabolism is to tell the brain that the body has eaten enough food. When tests show low leptin levels, it suggests the endocrine system is working properly or that appropriate amounts of this enzyme are being produced. High levels are an indication to seek advice from an endocrinologist.

When such tests are performed on obese people, they generally are found to produce a high amount of this hormone, even in early morning fasting tests. Such patients are thought to suffer from leptin resistance, in which their brains do not receive the signal that leptin levels are high. This is considered analogous to Type 2 diabetes patients who do not respond to the insulin that is present in their bodies. Some hugely obese people do not produce this hormone at all, and can benefit from injections of molecules produced by genetic engineering and do subsequently lose weight.

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Discuss this Article

anon349417
Post 4

I am obese with a BMI of over 50. I just got my leptin test back today from my endo. It was 18ng. I am a 38 year old female. My doctor said with my weight, my test should have been 100ng - 140ng. He fears that my body doesn't make enough leptin and I may be leptin deficient. My mother and three sisters are all obese. I does believe this gene deficiency is genetic.

Since leptin deficiency is so rare, he is making me retake the test to double check before he puts me on leptin injections. All my life I have struggled not to gain weight even when I was dieting and exercising. I just kept gaining and gaining even though the thin people around me stayed the same even though their food choices were bad. So I guess I have some messed up obesity gene.

I wish all those horrible doctors who blamed me for my weight my whole life would have just tried a little harder and tested me leptin 35 years ago!

ysmina
Post 3

@alisha-- I think what you're describing is leptin resistance. People who have reduced leptin sensitivity or leptin resistance have extremely high leptin antibodies in their ELISA.

discographer
Post 2

@SarahGen-- I'm not a medical professional, but from my experience, leptin testing is sometimes helpful and sometimes not. It's helpful if it does turn out that you have lower than normal leptin levels. But if the results come out normal, it can be misleading.

Some people have enough leptin, but suffer from a decreased leptin sensitivity. What this means is that the body is not recognizing leptin as it should. If this is the case, leptin testing is not at all helpful because the doctor may just brush it off saying that your leptin levels are normal.

Still, it's a good idea to get it done, just to know where you stand. If you are deficient, you can be treated with leptin tablets or injections.

SarahGen
Post 1

I have been struggling with obesity for several years. Nothing has helped me lose weight. I just found out about leptin and I think that my body might not be producing enough. I have an appointment with my doctor next week. I'm going to ask him if I can get tested for this.

If I turn out to have a leptin deficiency, what's next? Will I just have to take a leptin supplement?

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