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Effect of alcohol on blood and urine test results
Last reviewed: 04.07.2025
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Each of us has to take tests. They are taken for different purposes: some need them for prevention, others - for a regular medical examination, for obtaining certificates and medical books. Some - for a full diagnosis and determining further treatment. Whatever the purpose of the study, it cannot be treated dismissively. It is necessary to carefully prepare for the analysis, exclude all factors that can affect the result. In the rhythm of modern life, we often forget about the effect of alcohol on tests. Sometimes, having received a referral, in the evening we go with friends to relax, unwind, where often, whether we want it or not, we forget about the tests. Many remember that alcohol can affect the tests only in the morning, the day before taking the tests.
Any analysis aims to determine the indicators of the main processes that occur in the body. Thanks to this, you can analyze the situation. If the test results are normal, you can not worry, but if the results are outside the norm, it is possible to make a timely diagnosis and take appropriate measures. In any case, the accuracy of the tests determines the correctness of the diagnosis, and accordingly, the success of further treatment. Having received incorrect results, you can miss the pathology, thus starting the disease, making it chronic and severe. Therefore, if there was a noisy party in the evening, or you relaxed and allowed yourself to drink even a small amount of alcohol, it is better to postpone a visit to the laboratory. It is worth waiting 1-3 days, and only then take the tests, being confident in the reliability of their results.
How does alcohol affect tests?
Alcoholic beverages affect the main chemical and biological processes in the body. Accordingly, the results change. In order to obtain correct and reliable results, you need to exclude alcohol approximately 2-3 days before.
Ethanol affects each type of research differently. First of all, blood tests and biological secretions change. In general, the body experiences a sharp increase in lactate, various types of metabolism are disrupted, in particular, the metabolism of vitamins and microelements. Alcohol dramatically changes the hormonal background, the production of hormones by the glands is disrupted. Alcohol even affects the diagnosis of viral and bacterial infections. False negative and false positive results may occur.
Both false positive and false negative results pose a serious danger. With false positive results, a disease can be missed and proper treatment cannot be prescribed when necessary. As a result, serious complications can develop, or the disease can become chronic. False positive results are dangerous because a person can be treated for a long time for a disease that he or she does not actually have. This undermines the immune system, changes the hormonal background, can cause numerous undesirable reactions in a healthy organism, or lead to the development of this or a related disease. For example, uncontrolled use of medications often causes gastritis, ulcers, and metabolic disorders.
Surprisingly, there are certain tests known in medical practice that require preliminary intake of a small amount of alcohol. However, they are quite specific and are rarely encountered in everyday practice. If such a case arises, the doctor will definitely warn you.
There is only one conclusion: in order to avoid dire consequences and to avoid harming yourself, it is better to refrain from going to the laboratory if you drank alcohol the night before.
How does alcohol affect blood tests?
Alcohol acts individually. Ethanol can improve the condition of the blood, in some cases, on the contrary, worsen it. Alcohol changes the indicators of red blood cells. Accordingly, changes can also affect hemoglobin, which carries oxygen. The main active ingredient of alcoholic beverages is ethanol, which acts as a solvent. Under its influence, the red blood cell membrane dissolves. Their movement becomes chaotic, the cells stick together, which is presented in the results as a reduced number of red blood cells. The amount of hemoglobin, accordingly, decreases. A false diagnosis can be made - anemia, decreased blood clotting.
As a result, blood viscosity increases, blood clots form, which can easily penetrate through the capillaries. Partial adhesion of platelets occurs, their number decreases. Often, based on such results, an erroneous diagnosis is made - thrombocytopenia. The amount of cholesterol also increases significantly. The properties of blood plasma deteriorate: the synthesis of plasma lipids decreases significantly.
In general, the clinical picture of blood in a person after drinking alcohol is similar to an inflammatory process and acute intoxication. If there were additional additives and impurities, the number of eosinophils and the amount of released histamine may increase. This indicates an allergic process.
All these indicators have an important diagnostic value. They are used in selecting treatment, preparing for operations, determining how the recovery process is proceeding, wound healing. If a person regularly abuses alcohol, all these indicators give a persistently distorted picture.
The Effect of Alcohol on Urine Analysis
In most cases, urine analysis is prescribed to detect certain substances. Under the influence of alcohol, substances that have diagnostic value may not be detected at all. Instead, other substances may be detected. Various chemical reactions and transformations may occur in the body, which entails numerous false positive and false negative results.
In general, the analysis performed after drinking alcohol in the evening becomes completely meaningless. The uric acid content increases sharply, the lactate concentration increases significantly. The glucose and triacylglycerol levels may change. All the main components are often sharply overestimated, which allows for an incorrect diagnosis. Most often, in such a case, an active inflammatory or infectious process is assumed.
The kidneys work intensively because they are aimed at cleansing the body of harmful and toxic substances, as a result of which many toxic substances will be found in the urine, which allows for an incorrect diagnosis. In addition, intensive kidney work is associated with fluid loss, as a result of which the urine becomes more concentrated.
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HIV and alcohol testing
An HIV test is absolutely incompatible with alcohol. You can get a false positive result. Firstly, it is a severe stress, a nervous shock to learn such news. Secondly, AIDS therapy involves the use of the strongest medications that have a powerful effect on the entire immune system. Stimulation of the immune cells of a healthy organism will lead to aggression against its own organism, which ends in serious autoimmune reactions and diseases that are aimed at destroying its own organism. The side effects of antiretroviral therapy are quite serious for treating a sick organism. And for a healthy one, even more so. Such "treatment" of a non-existent HIV infection can even end in death.
False negative results for AIDS are no less dangerous. Firstly, a person will be absolutely calm and will not take any measures for timely treatment. But if you take timely therapy, you can significantly prolong life and improve the quality of life. Today, AIDS patients, thanks to timely diagnosis and properly selected antiretroviral therapy, along with symptomatic and supportive treatment, live 30 years or more without suffering from the disease. Secondly, a person who does not know about his disease is a source of infection, infecting other people.
Most often, if alcohol is present in the blood, a false positive result for HIV is obtained. This is due to the peculiarities of the immune system, which actively produces antibodies in the blood that can react with the test system. Also, after drinking alcohol, the load on the liver increases significantly. The liver produces various components and antibodies that are similar in many respects to those in AIDS. They are the ones that react, resulting in a false positive result. After drinking alcohol, there are disturbances in the endocrine system, which entail pathological reactions of the immune system, the production of antibodies.
In case of a false negative result, the unreliability is primarily due to the fact that with AIDS the number of leukocytes in the blood decreases sharply. After drinking alcohol, there will be even fewer of them, since they stick together. Accordingly, the number of antibodies produced in relation to the virus decreases. The number of antibodies may be so small that they simply will not react with the test system, which will allow the doctor to exclude the disease.
Alcohol before hormone testing
Alcohol can significantly affect the endocrine system and hormone synthesis in the body. The adrenal glands, thyroid gland and parathyroid glands are most sensitive to the action of hormones. The adrenal glands are responsible for the synthesis of "stress hormones" - adrenaline and noradrenaline. Alcohol is stress for the body, the activity of all organs is aimed at eliminating its negative impact, neutralizing toxins. A large number of hormones that are released into the blood can be mistaken for dysfunction, hyperfunction, or another pathological condition of the adrenal glands.
Hormones of the thyroid, parathyroid, parathyroid glands also have a significant impact on metabolism, and are among the first to be activated when there is a need to neutralize a negative impact on the body. They directly depend on the functioning of the adrenal glands, and begin to produce their hormones in response to the release of adrenaline into the blood. A large number of hormones can also be mistaken for hyperfunction.
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How does alcohol affect stool analysis?
In general, alcohol does not have a significant effect on feces. Alcohol rather affects the intestinal microflora, which determines the consistency of the stool. Sometimes, alcohol can cause dysbiosis - a phenomenon in which representatives of the normal microflora die, and their place in the population is taken by pathogenic microorganisms. Their waste products are released directly into the intestines, irritate the mucous membrane, resulting in loose stools (diarrhea).
With excessive alcohol consumption, chronic alcoholism, blood may appear in the stool. This indicates various pathologies, primarily a pathological disorder of the structure and function of the liver, including cirrhosis of the liver. Also, the cause of blood in the stool can be an ulcer, ulcerative gastritis, intestinal cancer. This is due to the fact that alcohol is a potent poison, and sometimes a mutagen, under the influence of which irritation of the mucous membrane, its burn, and sometimes malignant degeneration occur.
After drinking alcohol, excessive amounts of mucus may appear in the stool. This is due to the intense activity of the gastric glands that produce gastric juice.
Yellow colored feces, or impurities of this color, may indicate a disruption in the functioning of the pancreas and liver, which produce a large amount of bile and enzymes.
Effects of alcohol on blood chemistry
Alcohol consumption has a particularly strong effect on blood biochemistry. First of all, the glucose level changes. In most cases, it drops sharply. The level of lactic acid (lactate) increases sharply. Often, such symptoms are mistaken for severe forms of circulatory disorders. They can even make a diagnosis such as heart failure or hemorrhagic shock. Also, under the influence of alcohol, the level of uric acid can increase. This indicator can be mistakenly diagnosed as gout or chronic arthritis.
Alcohol significantly increases the amount of triacylglycerides, which may indicate atherosclerosis, thrombosis, and other similar diseases.
Alcohol and Syphilis Testing
After drinking alcohol, you can get false negative or false positive results of the RW test. Most often, you get false positives. The mechanism is similar to that of the HIV test. In response to syphilis, the body produces antibodies that bind to the test system and indicate the presence of the disease. When drinking alcohol, the immune system begins to stimulate the synthesis of antibodies against alcohol toxins. They can mistakenly bind to the test system and indicate the development of a disease such as syphilis.
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Does alcohol affect smear analysis?
The results of smears can be affected by many factors, including alcohol. The most significant effect of a smear on the results of smears from the throat and nose. This is due to the fact that alcohol passes through the mucous membranes of the throat, nose, and has a bactericidal effect. Thus, some bacteria can die under the influence of alcohol, and thus the result will be erroneous, since it will show a lower degree of bacterial contamination than it actually is. Dysbacteriosis can also develop. In this case, normal microflora is replaced by pathogenic, bacteria can be replaced by fungi, which significantly changes the real picture of the pathology.
As for smears from the mucous membrane of the urethra or vagina, a change in the ratio of microorganisms is also possible here. Their quantitative and qualitative composition also changes. This is due to the fact that alcohol in secretions can contribute to irritation of the urethra, and accordingly, a change in the composition of the microflora, quantity. In addition, the composition of the nutrient medium for microflora changes, since alcohol appears in natural secretions, which serve as a medium. It helps to reduce the number of microflora, since it has a bactericidal effect.
In addition, when examining the microscopy, the doctor may detect a large amount of mucus, leukocytes, and erythrocytes. Sometimes, desquamated epithelium may appear. This may be mistaken for an inflammatory process.
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Pregnancy test after alcohol
Alcohol does not affect the pregnancy test results because it reacts to the hCG content in the urine and has nothing to do with alcohol. If there is a pregnancy, then no matter how much alcohol was drunk, the test will still show a positive result. If there is no pregnancy, the result will still be negative, regardless of alcohol.
Does Alcohol Affect a Drug Test
The effect of alcohol on drug tests has not been fully studied. Theoretically, alcohol does not affect the results of a drug test. There are separate alcohol tests that are designed to detect the alcohol content in the blood. Drugs and alcohol are substances of different origin, they are tested using different methods and cross-reactions are not observed.