- Is an Abnormal Result Always Dangerous?
- The report says “abnormal” but my doctor said, “everything looks good.” What’s up with that?
- WHEN SHOULD I START TO WORRY ABOUT A TEST RESULT?
- So if an abnormal test can be unimportant why bother testing?
- Could it be a mistake? Random Variation, Handling, and Technical Factors.
IS AN ABNORMAL RESULT ALWAYS DANGEROUS
- No, an abnormal lab test is not always dangerous.
- The range of normal for a test result is based on what is average for a certain group of people, hopefully, a group you would fit into.
- The range is determined by what is normal for 95% of a population.
- Not all healthy, normal, people will fit into the range.
For example: If you are a 6′ 5” tall American male are you abnormal? If this was a lab test the answer would be “yes you are abnormal.” This is because 95% of American men are between 5’6” and 6’4” tall.
But is you asked: If you are a 6’5” tall Norweigan are you abnormal? The answer is no. It’s a different population and 95% of men from Norway fall between 5’8” and 6’6”.
- When looking at lab tests the principle is similar. By definition of normal and abnormal, some test results will fall outside the normal range.
- So even if you are perfectly healthy, it is likely that 5% (5/100) or 1 out of 20 of your tests will not be normal. Just by chance.
- Put another way, If you do a test on 100 healthy people off the street, let us say we measure their WBC count, chance would have it that 5 results will be abnormal, even though everyone seems perfectly healthy.
- On a test panel such as a complete blood count (CBC) which includes many measurements, It is unlikely that all results will be completely normal.
THE REPORT SAYS “ABNORMAL” BUT MY DOCTOR SAID EVERYTHING LOOKS GOOD. WHAT SHOULD I THINK?
- Sometimes a slightly or mildly abnormal result is completely unimportant.
- Even though the lab has marked it as abnormal in your doctor’s mind, it is close enough to normal, unchanged from your previous results or expected given your medical history.
- So if you see abnormal results but they tell you “everything looks good” that may not mean that all the tests are completely “normal.” It usually means that everything is as expected for you, or so close to normal as to be unimportant. So don’t worry too much.
- Their failure to mention or explain these is usually not laziness or oversight but due to the inconsequential nature of the result and the time and confusion required to explain this to the patient.
- Some abnormal results “go with the territory.” That is they are expected based on your known medical conditions or state of health. For example, it is “normal” to be mildly anemic in pregnancy and to have a mildly elevated white cell count. A chronic kidney failure patient is expected to have a low blood count. The lab report does not consider these things. Your provider is considering these factors when they tell you everything looks “normal.”
- If you are concerned about an abnormal result that was not mentioned, the best thing to do is quickly “replay” the results to your provider. Write down a list of the test results you are concerned about and say to them “my calcium is 8.5 and my hemoglobin was 9.9 is that OK?” This way you can be sure that they recognized and considered the “abnormal results.”
SO IF AN ABNORMAL TEST MAY BE UNIMPORTANT WHY BOTHER TESTING?
- Your doctor is looking for severe or unexpected abnormalities or abnormalities that are in agreement or disagreement with the suspected diagnosis. They are looking for trends in your tests over time. Sometimes the trend is more important than the numbers.
WHEN SHOULD I WORRY ABOUT AN ABNORMAL TEST RESULT?
- Hopefully, your provider will tell you within a safe time frame if a result is concerning.
- Dangerously abnormal labs should be flagged in your lab report as “critical,” or “HH,” or “Panic Value.” At least in hospitalized patients, critically abnormal labs trigger a call from the lab to the nurse or doctor, so they should know within a few minutes of the result. If you are at home and receive a report with a value that is in the critical range you should contact your provider immediately unless this is a known and expected result based on your condition.
Random Variation,
Specimen Collection, and Handling Errors,
Other Technical factors.
How do you know if your test result is accurate? The vast majority of reported results are reliable. However inaccurate results do occur. The most important factor for your health care provider is to identify situations when the result does not make sense, given all she knows about your condition. If the facts don’t fit the result, it is often reasonable to repeat the test.
Random Variation
- Even when THE SAME BLOOD sample is tested more than once, there will be some small variation between “runs.” More so if two different samples from the same patient are compared. Your doctor may not mention the change in a test result over repeated tests if the difference falls within the expected random variation. In their mind it is unchanged.
Specimen and handling errors
- These can affect test results, making them appear very abnormal when they are in fact normal.
- Perhaps the most common is high potassium levels caused by the breakup of blood cells during the blood collection and handling process. This is called “hemolysis.” If hemolysis is present it should say so on your report. It is common for patients to receive a phone call telling them to go to the Emergency Room immediately because their potassium level is critically high. This is the correct thing to do as high potassium is very dangerous. Fortunately, many of these cases are due to hemolysis and patients can be sent home safely when the test is checked again and found to be normal. Hemolysis is hard to avoid sometimes. Drawing blood using a larger needle can reduce this, but often that is not possible.
- Hemolysis can affect the results of many other tests including Calcium, Troponin T, Liver enzymes, Bilirubin, and multiple others.
- Many other factors can throw off a test result. Some blood test samples must remain on ice until they are processed. Otherwise, the result will be abnormal. Prolonged placement of a tourniquet before blood is drawn can affect calcium levels. Waiting too long between the time a specimen is collected and placed on the processing machine can affect some results. In rare cases, certain medications can interfere with testing. These events are relatively uncommon causes for abnormal test results.
Technical Factors
- Clinical laboratories in the U.S. and most developed countries are highly regulated. Machines are tested against standard samples to ensure reliability and precision. Overall they perform at a very high level.
- But occasionally things go wrong, machines and people err.
- It can’t be stated often enough, if the result does not fit the clinical picture, repeat the test.