What do my test results mean?
We have prepared this document to help you understand some of the laboratory studies and other tests which may have been done at your recent physical exam. Please realize that this is not meant to be a lesson in interpreting laboratory studies. Rather, it is intended to be a basic explanation of some of the specific tests we use to help understand your health issues. Minor deviations from normal are common and do not mean a problem exists. Conversely, normal findings can occur even though a disease is present. The point is that these studies require a careful interpretation by your physician based on your history and examination. You might want to print these results out and keep them in your paper file for future reference.
Glucose - your blood sugar, it will rise after a meal. Average fasting values are up to 100. Values of 100-125 are defined as pre-diabetes and values above 125 are defined as diabetes.
Sodium - the mineral "salt". Low levels can be seen with certain diuretics and with over-hydration. High levels can occur with dehydration and with certain endocrine conditions. Its level does not correlate with the ingestion of salt. Generally, this study is of value only when outside of normal ranges.
Potassium - a mineral "salt" that helps run the electrical system of the body. Levels often fall when a patient uses diuretics. Potassium is found in juices and fruits. A normal level is very important in maintaining normal cardiac rhythm and avoidance of muscle cramps.
Chloride - the other part of sodium, but which reflects acid-base balance. Generally, this study is of value only when outside of normal ranges.
CO2 - reflects acid-base balance which is controlled by both the kidneys and respirations. Generally, this study is of value only when outside of normal ranges.
BUN & Creatinine & BUN/Creatinine Ratio - a reflection of the state of hydration and kidney function. These levels are usually elevated when the blood is drawn after a 12-hour fast.
GFR (glomerular filtration rate) - a crude calculation of how much urine is cleared of creatinine every minute. Generally, this study is of value only when outside of normal ranges.
Calcium - a mineral normally stored in tremendous quantities in bone, which exists in equilibrium with blood calcium. Abnormalities of bone, the endocrine system, and certain types of malignancies can increase the calcium level, while poor oral intake of calcium, kidney disease, or lack of vitamin D can decrease its level.
Total Protein - this reflects many serum proteins, including those involved in maintaining fluid balance, fighting infection, and helping blood coagulate. Low levels are seen when protein is lost in the urine, or is not produced due to liver disease or poor nutrition. High levels can reflect underlying inflammation.
Albumin - a serum protein which prevents water from leaking into the tissues and causing edema (swelling). It also carries many hormones and binds them until they are actually needed.
Globulins - the proteins involved in immune responses. The level is roughly estimated by subtracting albumin from total protein. An elevation in the globulin level usually indicates a need for additional testing.
Total Bilirubin - a pigment produced by the liver and by the natural breakdown of red blood cells. It is deposited in the skin in jaundice and is the reason why a bruise ultimately takes on a yellow-green hue.
Liver Enzymes - includes Alkaline Phosphatase, SGOT, and SGPT, which are all enzymes that originate in the liver. Discussing the interpretation of these values is beyond the scope of this document. Generally, values up to two or three times the upper limit of normal are when the levels from these studies become important. Elevations in these levels may lead us to suggest additional blood testing or an ultrasound checking for structural abnormalities.
Cholesterol - a blood fat largely determined by genetics and production within the liver. Dietary choices and exercise have a secondary impact on cholesterol levels. Increased levels may indicate an increased tendency towards atherosclerosis, meaning an increased risk of heart disease, stroke, and peripheral vascular disease. Heredity, weight, body habitus, body mass, and level of exercise are very important co-determinants of cholesterol level.
Cholesterol is composed of several components. The most important ones are HDL (the "good" cholesterol) and LDL (the "bad" cholesterol). In general, high levels of HDL and low levels of LDL are associated with a decreased risk for heart disease, whereas low levels of HDL and high levels of LDL are associated with an increased risk. HDL values are genetically predetermined, but can increase in those who exercise regularly. Targets are an HDL above 50 for men and above 60 for women. LDL values behave exactly the opposite. These levels are also affected by your genetics, and are often related to a diet rich in saturated fat (animal fat) and excess alcohol intake. Ideal target levels for LDL are under 100 but new data suggest that even lower levels may still offer added risk reduction for heart disease. Triglyceride levels have been under-emphasized, but are a critical risk factor for cardiovascular risk. Elevations in triglyceride levels often occur as part of a syndrome called metabolic syndrome, implying an increased risk for heart disease and diabetes. Any triglyceride value above 100 is linked with increased cardiovascular risk.
And remember that lots of people with adverse cholesterol panels do not have heart disease, while many with excellent profiles do. Cardiac risk is multi-factorial. And this, more than many other areas of medicine, requires a physician who can integrate clinical knowledge of risk factors into your particular health history to make appropriate recommendations. This is a great place to do a heart scan because remember high cholesterol is not the disease. The disease is atherosclerosis and that’s what you must identify.
CBC - the complete blood count measures hemoglobin (the oxygen-carrying molecule), the white blood cells (which are involved in defense against infection), and the platelet count (which are involved in clotting). Abnormalities on a CBC could indicate things like anemia or bleeding.
Thyroid - TSH and free T4 are tests that reflect the level of thyroid hormone produced by the thyroid gland, a small butterfly shaped gland located in the front of the neck. It is the body’s thermostat and sets the metabolic rate. An underactive thyroid may lead to fatigue, weight gain, and constipation and is characterized by an elevated TSH level, and a low free T4 level. An overactive thyroid may lead to weight loss, frequent stools, and tremors, and is characterized by a very low TSH level and elevated free T4. We do not always do a free T4, but we usually do a TSH level with a physical.
Uric Acid - a material which results from the natural breakdown of cells and normal metabolism. In excess, uric acid can deposit in the urine causing kidney stones or in the joints leading to gout. Some blood pressure drugs, diets with large amounts of rich foods, and alcohol will frequently raise the uric acid level. This is not part of the routine laboratory profile but is done when there is a suspicion of gout.
Urinalysis - used as a screening test for diseases of the urinary system (which include stones, infections, and tumors) as well as a screen for systemic diseases (hypertension, diabetes, and lupus, for example) that can affect the kidney.
Sedimentation Rate (also called SED rate or ESR) - a test which tells us if something is inflamed. It does not make a diagnosis, but rather tells us that more evaluation is needed. The normal range rises with advancing age.
PSA (for males only) - a valuable screening test for prostate problems, including cancer. Its level will rise with prostate infections, sometimes with enlarged prostate glands, after trauma (such as riding a bike or horse), and in those with prostate tumors. It is always interpreted in the context of an examination, but also important is the rate of change. So if a PSA were to double, even though both values were in the normal range, this is potentially a very serious issue. It is very important to realize that an elevation is absolutely not the same as having prostate cancer. It is just a flag telling us to repeat the study.
Hemoglobin A1C - a study used to monitor overall control of diabetes for the preceding 3 months. However, it is also a useful screening for non-diabetics or early diabetics. When people come in for a physical, they are usually very compliant with diet for the days before the physical, so the glucose level we get is usually excellent. The hemoglobin A1C study gives us an overall picture of the last 3 months of blood sugars, so we can get a more true assessment of diabetic risk. As values rise above 5.6% and move towards 6%, there is a definite trend toward the development of diabetes.
Cardiac C-reactive protein (CRP) - This study looks at cardiac risk from the perspective of vascular inflammation. Most studies suggest that this test is a more active predictor of heart disease risk than cholesterol, and some studies suggest that very high levels of cardiac CRP should prompt a search for problems beyond the heart. The utility of this test is that it identifies those who may be at increased risk, which prompts advice to have additional testing. Many insurance companies will not cover this study. It is new technology and they are not keeping pace with advances in medical care and early diagnosis. But remember, it was not too long ago that Pap smears, colonoscopies, and mammograms were not covered either.
Fecal occult blood (take-home kit) - a much different study than the older version, called a hemoccult. This newer study is specific for human hemoglobin, which eliminates some of the concern about false positive results. For example, the older study would detect blood, horseradish residue, or vitamin C, and appear positive. This newer study uses a combination of antibodies directed specifically at human hemoglobin. The presence of blood does not mean you have a problem, it simply means we need to revisit this issue.
Vitamin D level - frequently done in women with suspicion of osteoporosis or bone loss, but it is a very valuable study in most people. Vitamin D relates directly to calcium metabolism and strength of bone. However, it has also been linked with a low or reduced risk of colon cancer among women in particular. Thus, a level of Vitamin D < 30 is something that should be addressed with supplemental vitamin D. Levels are generally greater during the summer because the active form is produced with sun exposure.
Testosterone level - the male hormone; however it also has a very important role in women, and is now being studied as a treatment for postmenopausal loss of libido. In men, a deficiency of this hormone frequently presents as fatigue, loss of muscle mass, loss of libido, and diminished fertility. It can be rectified with the daily application of cream/gel.
Urine Microalbumin - another very useful study for identifying excess cardiovascular risk. It is also useful in patients with diabetes or suspected diabetes, and for identifying inflammation, which is a well-established factor in cardiovascular risk. This study is used in patients with high blood pressure, excessive cardiac risk, diabetes, or any type of kidney issue.
Advanced Cholesterol Testing - Cholesterol management is more complex than just LDL and HDL cholesterol. Optimal medical management requires much more in-depth information. An affordable test to help glean the detail about your particular cholesterol panel is called a Cardio IQ panel, which we only recommend for patients who have suspected elevated risk for cardiovascular disease. Most insurance companies do not cover it, but we have successfully negotiated a very fair cash price of $145. It provides a large amount of detail about your cholesterol and allows us to get the detail to give you optimal treatment.
This advanced profile identifies the number and size of the different cholesterol particles, and the nature of the proteins that actually wrap the cholesterol molecule, which determine their risk. The results will tell us when certain therapies like a low-fat diet, fish oil, or alcohol should be avoided or utilized.
Hearing Screen or Otoacoustic Emission Screen (OAE) - a simple hearing screen that helps us to determine if someone needs additional testing. Frequently these studies detect abnormalities when you did not notice any, but it should put you on notice to be cautious with noise, and to always use appropriate hearing protection. Be particularly conscious of wearing the ear buds that come with many MP3 players. When sound waves hit the hair cells of your ear they make a sound which is what you hear; this study measures that sound to see how well your hair cells are working, and, in turn, how well you are hearing. It is like measuring the sound that rustling wheat makes in the wind.
Heart scan or coronary artery calcification screen - The reality is that we do not know who has heart disease. We have several different tools but they are indirect measures. High cholesterol does not mean there is heart disease, and low cholesterol does not mean there is not heart disease. This is important to know and that’s why we frequently use a heart scan. This is an appropriate study when there is concern about cardiac risk either due to metabolic abnormalities like diabetes, hypertension, an adverse cholesterol panel, or a strong family history. This study can identify heart disease way before a stress test can, which is why it is so valuable.
This test identifies calcified atherosclerosis of the coronary arteries (called hard plaque) at a time when we have treatment options. If we find calcification then we need to reduce your cholesterol with diet, exercise, medication, or all three. This study will not be covered by insurance because insurance companies regard it as a newer technology and as a preventive study. It is an outstanding and clinically useful study. A stress test as an initial screening tool in an asymptomatic patient is not optimal because one can have a significant artery obstruction, pass a stress test, and think everything is fine. That’s why we favor the heart scan as a screening study: it tells us if atherosclerosis has begun, giving us a chance to intervene.
Vascular Screening - If we find coronary calcification, or there are other significant risk factors for cardiovascular disease, this is an advisable test at the age of 50 to look for evidence of atherosclerosis. The purpose is to identify narrowing in the carotid arteries which can be markers for future stroke, and look for swelling in the aorta which can be a marker for a future condition called an aortic aneurysm. The idea is to keep you out of trouble, not deal with it once it takes place. Both of these things can be provided in our office, so please call and schedule. And like all preventative studies, your insurance will not cover it, but cost is $130. It is also a once every 5-10 year study. If an abnormality is identified on the screening, then we would convert it to a diagnostic study, involving significantly more detail.