A blood draw only takes a few minutes, but a person may have to wait a few days or weeks for the test results to come back. The waiting time depends on what the blood test is looking for.

This article looks at how long it takes for different types of blood test results take to come back, and the factors that affect these timings.

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The time it takes for results to arrive depends on the purpose of the blood test.

Doctors use blood tests to check blood counts, cholesterol levels, and help diagnose nutrient deficiencies or medical conditions. The timings of the results will depend on the type of test.

According to the National Heart, Lung, and Blood Institute (NHLBI), the actual blood draw usually takes less than 3 minutes, and the results can take anywhere from a few minutes to a few weeks to come back.

The laboratory that tests the blood sample usually sends the results back to the doctor's office. A doctor can then go over the results over the phone or, in some cases, during a face-to-face appointment. It is essential to follow up with the doctor to discuss test results.

In other cases, a lab may release results directly to a person, often through an online portal. The lab should tell the person how long it could take to receive results back.

Sometimes, unforeseen factors can delay a person's results. For instance, a person may not receive their results if the doctor did not collect enough blood or if the blood sample became contaminated. A doctor may reorder the test if the sample is inadequate for any reason.

The following are some potential reasons a doctor may order a blood test and how long a person can expect to wait before getting the results back.

A basic metabolic panel is one of the most common blood tests. It provides information about a person's current metabolism, blood glucose levels, kidney health, and the levels of elements in the blood, including acids, bases, and electrolytes.

In preparation for the test, a doctor may instruct a person to fast for up to 12 hours before the test.

The doctor's office typically receives the results within a day.

The complete blood count (CBC) indicates the white blood cell count, the red blood cell count, and hemoglobin levels. Similar to the basic metabolic panel, the lab typically returns the results to the doctor's office within a day. There is no need to fast before a CBC.

A lipid panel measures the amount of cholesterol in the blood. The test measures both the high-density lipoprotein (HDL), or "bad cholesterol," and low-density lipoprotein (LDL), or "good cholesterol." A person's doctor should receive the results within a day. Most adults will need to fast (water only) for 9 to 12 hours before the blood test. However, children and young adults can eat as normal.

A complete metabolic panel includes tests that measure levels of albumin, total protein, glucose, calcium, and common electrolytes included in the basic metabolic panel. This test can tell a doctor about how a person's liver or kidneys are functioning.

The results of a complete metabolic panel can take a few days to come back. A person will need to fast for 12 hours before having this blood test.

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A urine test can detect pregnancy more quickly than a blood test.

Urine tests are the most common methods for detecting pregnancy and give results within minutes. Some people choose to have a blood test, which tends to be more accurate than a urine test. However, people have to wait longer for blood test results.

There are two types of blood tests for pregnancy: quantitative and qualitative. A quantitative test gives a simple yes or no answer to whether a person is pregnant. A qualitative test returns the total amount of human chorionic gonadotropin (hCG) in the blood. The body produces this hormone when someone becomes pregnant.

Some blood tests can detect whether a person is pregnant as soon as 1 week after conception. A person needs to be pregnant for longer before a urine test can identify a pregnancy accurately.

How long a pregnancy test result takes to come back depends on the location of the lab. If the lab is in the doctor's office, it could take a few hours; otherwise, the results could take a few days longer.

A doctor can use a blood test to confirm suspected cancers. The type of blood test will depend on the type of cancer a doctor is looking for. The results can take a few days to a few weeks to come back, depending on the lab and the location.

Several different tests look at thyroid functions. Doctors can check for hyperthyroidism (overactive thyroid) or hypothyroidism (underactive thyroid). The results for the various thyroid tests are often available within a day or two, but this can vary between labs.

There is a variety of tests a doctor can run to look for anemia. Some examples include a CBC or hemoglobin and hematocrit (H and H) test. Typically, results only take a few hours to come back.

However, there are some rapid tests available. If a doctor uses a rapid test, it could take only a few minutes to get the results.

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A doctor can advise on the best type of blood test for detecting STIs.

Sexually transmitted infections (STIs) can take some time to show up. A person may initially test negative for a STI shortly after contracting it, but symptoms may appear later. The length of time for results to come back depends on the specific infection.

When testing for HIV, a healthcare provider can perform a finger prick blood test in the office and receive the results within minutes. Laboratory based tests for HIV are more accurate but take longer to perform. They may take 30 minutes to 3 hours.

Doctors often take swabs of the mouth or genitals to test for many STIs. They can take a few days to come back. Tests will take longer if the technician needs to grow cell cultures to check for the presence of specific microbes.

Finally, a doctor may use a blood test to look for syphilis and herpes. In these cases, results may take several weeks to come back.

Blood test results can take several minutes to several weeks, depending on the test. It is common to wait a day or two for most results to come back.

A person should talk to their doctor or lab about what to expect regarding their test results. They should be able to tell a person how long it will take for results to come back and who will receive them. They can also help a person to understand the results.