“Am I Ok if All My Lab Work is Normal?” by Richard Zhen Lu, M.D.

Board Certification: Family Practice

Recently a few patients contacted me after their annual physicals to inquire about their lab work.  Blood work is an important part of the annual physical; there are some tests that are almost always ordered, such as comprehensive metabolic panel (CMP), complete blood count CBC), and fasting lipid profile (FLP).  Most laboratories usually have a set range for normal values of any particular test. It is significant to understand that a fair number of lab results are subject to certain errors and in most cases require interpretation depending on the patient’s symptoms and signs.  It is entirely possible that two patients could have similar lab values, yet the results have different implications for those individuals.  Typically an abnormal lab test will require a repeat test to confirm the result; often times an isolated abnormal lab result may not necessarily mean an abnormality in the patient.  Different laboratories may employ different normal ranges for the same test, therefore results cannot always be directly compared between laboratories.

Medical laboratory tests are often grouped when they are reported because a group of tests can give more information about a disease or body organ than any one single test. The complete blood count is a common test that most physicians order which examines three different subsets of the cells: red blood cells, white blood cells, and platelets.  Based on the value of the hemoglobin and hematocrit, it can be determined if someone is anemic or not.  White blood cell count typically goes up when the body is fighting a bacterial infection, such as pneumonia.  Platelet level is used to assess part of the blood clotting system.  Under the comprehensive metabolic panel, there are several key parameters that most physicians closely examine.  Fasting glucose remains one of the gold standards to screen for diabetes.  Also found in the CMP is kidney function (BUN and Cr) and liver function (ALT and AST).  For example, in the case of acute hepatitis, we can often see a significant rise in the values of ALT and AST.  The calcium and phosphate levels are part of the kidney tests because kidney malfunction can affect bone health and vice versa.  In the case of multiple myeloma, which is a cancer from the bone marrow, we often see a moderate raise in Cr, part of the kidney function test, while the blood calcium level is significantly higher than the normal range.

Whenever you have lab work done at your physician’s office, it is necessary to follow up with your physician, with regard to your lab results, even if they may appear fall into the normal range.  It is necessary to make sense of the lab results in the context of your particular situation.