Does Drinking Coffee Before Blood Tests Affect the Results?

Coffee (Image from WIkimedia)Blood tests are among the most important laboratory tests to help diagnose many human diseases. Physical, chemical, and biological properties of the blood give a big picture on the condition of the body. Blood tests can tell if there is a problem on your kidney, heart, liver, glands, brain, muscles, bone marrow, etc. Without blood tests, it would be really hard for doctors to know what’s wrong inside your body. Blood tests are also important in monitoring the effectiveness of the medications you are taking. Blood tests can determine whether the drugs for your hypertension/diabetes/cancer/infection/etc. are working effectively. Examples of blood tests are BUN, LDH, ANA, ESR, GGT, and MPV.

An accurate blood test result will give an accurate diagnosis. It is therefore important to eliminate possible sources of error for blood test results. Eating and drinking can affect the result of certain blood tests. Doctors require their patients to fast before undergoing blood tests such as cholesterol and glucose blood tests. Patients who habitually drink coffee have one important concern: how does drinking coffee before blood tests affect the results.

Drinking Coffee Before Blood Test Affect the Results

Drinking coffee before blood test can affect the results of tests that measure blood sugar and cholesterol levels.

Coffee contains caffeine that is easily absorbed into the system at a fast rate. Caffeine can temporarily raise blood sugar levels resulting to an inaccurate fasting blood sugar (FBS) result. This happens as a result of caffeine’s stimulation of the pancreas to release insulin – hormone that regulates blood sugar level. Fasting blood sugar, commonly known as blood sugar level test, is used to diagnose diabetes and monitor hyperglycemia (too much blood sugar) or hypoglycemia (not enough blood sugar). Besides from caffeine, coffee (especially the roasted one) contains sugar in the form of polysaccharides.

Drinking coffee before blood cholesterol test should also be avoided. Coffee can alter the level of cholesterol in blood resulting to inaccurate result. Blood cholesterol test measures the level of bad cholesterol (low-density lipoprotein, HDL) and good cholesterol (high-density lipoprotein, LDL) in the blood. Higher level of LDL than HDL is considered unhealthy. Bad cholesterol plaques are deposited on the inner surfaces of the arteries obstructing blood flow. Many cases of heart attack and stroke are due to the obstruction of blood flow in arteries.

Other drinks that contain caffeine should be avoided before blood sugar and cholesterol tests. There are also other blood tests that will require you not to take coffee or other drinks. Normally, your doctor will tell all the do’s and don’ts before any test. Water is the recommended fluid to take before blood test.

There are also blood tests in which the results are not affected by drinking coffee. Examples are tests for bacterial, fungal, & viral infections, ANA, CBC, HIV and others.