APPENDIX 3

UNDERSTANDING LABORATORY TESTS

Laboratory tests are a useful tool for gathering information, but too often may fail to indicate problems in areas where attention is needed. A broad range of relative wellness exists between optimal health and overt illness; tests do little to indicate where in that range one lies. An awareness of the limitations of laboratory tests allows their use within the broader framework established by the medical history and the physical exam. Results of laboratory tests and special diagnostic procedures seldom surprise the discerning physician; rather, they usually confirm what was suspected after the history and physical.

Discussions of some routine blood and urine tests follow. The objective is to provide a simple and clear understanding of their purpose and meaning. Following this we will detail normal components of the blood and discuss how they may be impacted by disease.

COMPLETE BLOOD COUNT

The complete blood count (CBC) and an analysis of the urine (urinalysis) are basic screening tests routinely done to check for abnormalities. The CBC determines the number of red and white blood cells per milliliter of blood. Red blood cells (RBCs), with their hemoglobin, carry oxygen to all tissues of the body. White blood cells (WBCs) are part of the immune system; among other things, they attack bacteria and other foreign invaders. A significant increase in the WBC count usually indicates inflammation or infection.

Anemia is defined as the failure of the blood to deliver adequate oxygen to the tissues. The RBC count may be depressed in anemia, but in some types of anemia it never becomes depressed. Tests for hematocrit and for hemoglobin, also part of the CBC, are used to screen for anemia. The hematocrit test measures the percentage of the blood volume made up by RBCs. The hemoglobin test measures the amount of hemoglobin carried by the RBCs, thus determining the oxygen-carrying capacity of the blood. Both hematocrit and hemoglobin may also be normal in early stages of anemia.

On the other hand, the RBC count, hematocrit, and hemoglobin may all be below normal in a person with no signs or symptoms of anemia, and in good health. This is typical in those getting a great deal of endurance exercise—running, swimming, bicycling, cross-country skiing, or walking. Endurance exercise can cause the body’s total volume of blood to increase dramatically, reportedly up to 30 percent over time. With this increase, there are fewer RBCs per unit of volume. Still, because of the increased volume, the overall capacity of the blood to deliver oxygen to the tissues is increased. The three tests may be low simply because the blood volume has increased.

True anemia occasionally occurs in such individuals and may be difficult to diagnose. If suspected, anemia can be confirmed by further tests involving levels of iron and iron-carrying molecules in the blood.

The CBC also may include a differential, the description of a blood smear made on a glass slide that is examined microscopically. The relative number of different types of white blood cells is determined, both white and red blood cells are examined for abnormalities, and the number of platelets is estimated. Leukemia, bone-marrow failure, adverse drug reactions, various types of anemia, inflammation, and the presence of malarial parasites are some of the many problems detectable by the CBC.

URINALYSIS

Urine is routinely tested in several ways and examined under a microscope. Specific gravity (density) is a measure of the number of particles suspended in the urine, and indicates the ability of the kidneys to concentrate urine adequately. Sediments are concentrated by centrifuging a small sample of the urine specimen. They are then examined microscopically for presence of cells indicating problems of the kidneys, bladder, and associated anatomy.

Other tests are performed by dipping a paper strip into a sample of the urine. Small squares on the strip have been treated chemically to react individually to glucose (the form of sugar in the blood), protein, blood, and several other substances that may be found in the urine. Reactions cause color changes of the small squares that are read by the physician or medical technologist performing the test, giving approximate levels of the various substances. Abnormalities—for example, the presence of blood, sugar, or proteins—may be followed up by more quantitative tests. Abnormalities may also arouse suspicion about certain problems and indicate need for other tests and diagnostic procedures.

ERYTHROCYTE SEDIMENTATION RATE (ESR)

Erythrocytes are red blood cells. The ESR measures the extent to which erythocytes settle toward the bottom of a thin glass tube in one hour, which is a function of the relative amounts of proteins, antibodies, and other substances in the blood. In health, they settle very little. This is a nonspecific screening test, frequently done. The result is elevated in many diseases, and also, often, in a normal pregnancy.

The ESR is commonly used as a relative measure of the activity of autoimmune diseases in which the body reacts adversely to its own tissues, such as rheumatoid arthritis and lupus. In general, the more severe the problem, the greater the elevation.

The normal sedimentation range is up to ten millimeters per hour in men and twenty in women. In very healthy individuals, the ESR may approach zero. Although the blood may be thin due to endurance exercise, in an individual with proper diet the red blood cells scarcely settle at all in the test. Readings consistently between zero and one are commonly seen over the years in such individuals.

BLOOD-CHEMISTRY TESTS

Many substances normally found in the blood may become elevated or depressed in disease. Some are nutrients used by cells throughout the body; their levels may give indications about grossly inadequate nutrition. Others are byproducts of the metabolism of certain specific cells and, if elevated, give indications about disease in the organs in which those cells predominate.

This section doesn’t attempt to discuss all routine blood-chemistry tests. Rather, salient points, as well as a few more subtle points, about tests of concern to many individuals are explained.

Evaluating Cholesterol

Cholesterol is found throughout the body and is used in a wide variety of normal metabolic reactions. The human body makes, on the average, about three times as much cholesterol each day as the average diet contains. Cholesterol is as normal to human metabolism as any other nutrient found in foods. It is a constituent of all animal foods, and while cholesterol is found in the plaque that may build up in the arteries (including those to the heart, the coronary arteries) of some individuals developing heart disease, there is overwhelming evidence that dietary cholesterol is not the cause.

Many foods recommended in previous chapters are rich in cholesterol: liver and other organs, eggs, shellfish, dairy products, and meat. Evidence was presented demonstrating that these foods should be an important part of a healthy primal diet.

The laboratory result most frequently discussed in association with cholesterol is the serum cholesterol (serum is the fluid portion of the blood remaining after the red blood cells and clotting factors have been removed). Ironically, in my opinion, the only reason to measure cholesterol is to determine whether or not it’s too low. You read correctly. So-called high blood cholesterol is not a problem. It does serve as an excuse to prescribe some twenty billion dollars a year of cholesterol-lowering, highly toxic drugs.

Levels of cholesterol well over 200 mg per deciliter that were considered normal years ago are now classified as abnormally high. As the upper limit of normal has dropped, sales of cholesterol-lowering drugs have soared—circumstantial evidence of influence by drug companies on laboratory standards. There is no proof, but this reminds me of what Ralph Waldo Emerson once said when asked about circumstantial evidence that milk supplies were being watered down with water from the Charles River by milk distributors in nineteenth-century Boston. “Some circumstantial evidence is quite strong,” Emerson commented, “as when there is a trout in the milk.”

Low blood cholesterol is a different matter. It may indicate a plethora of problems caused primarily by a poor diet that lacks adequate quality animal foods.

Evaluating Triglycerides

Serum triglycerides are blood fats that are proving to be increasingly significant; they are the body’s chief storage form of fat. Dietary fats break down in the intestines, pass through the intestinal wall, and are reassembled as triglycerides as they are absorbed into the blood. These triglyceride molecules in the blood then transport fats throughout the body.

Because dietary carbohydrates are converted into substances that can be made into triglycerides in the liver, carbohydrate consumption can greatly increase serum triglyceride levels. This is especially true of simple carbohydrates such as refined sugar (sucrose), refined (white) flour, concentrated fructose (as in fruit juices or fructose that has been added to processed foods), and dried fruits.

All of these substances are absorbed and enter the blood very quickly. As a result, a more rapid rate of conversion to triglycerides occurs than when the complex carbohydrates of vegetables or whole grains are consumed. Alcohol also causes a rapid elevation of metabolites (substances formed in the body from precursors) in the blood, which are converted by the liver into triglycerides.

In recent years, research has indicated that elevated serum triglycerides are statistically correlated with heart disease. These metabolic pathways for dietary fats, carbohydrates, and alcohol indicate why so many Americans have high triglyceride levels. Overconsumption of alcohol and refined foods obviously contributes to this, but other foods commonly consumed and considered nutritious are also contributing factors. Fruit juice, as mentioned, is an example. Furthermore, fruit juice provides calories, without bulk to slow down digestion. Instead of consuming fruit juice, one is better off obtaining one’s vitamin C from fresh raw vegetables, fruits, raw dairy, and lightly cooked meat (raw milk and raw meat both contain significant amounts of vitamin C).

Fasting Glucose

Fasting blood glucose is the sugar level in the blood after a twelve-hour fast. It is measured in a standard chemistry screen that screens for diabetes. The results, as in the case of serum triglyceride levels, are influenced by the amount of refined flour, sugar, and other sweeteners, fruit, fruit juice, and alcohol in the diet.

Normal values for any given laboratory tend to be based on averages for the population it serves, however, the upper limit of normal for the fasting blood-glucose test has risen considerably over the years. Levels formerly considered indicative of possible or probable diabetes now often fall within the normal range. It should also be noted that the upper limit of the test can vary from lab to lab.

Regardless of a laboratory’s upper limit of normal, a result falling within the range of 100 to 130 should be considered borderline. If falling within this range, the test should be repeated—confirmation of elevation calls for further evaluation. A glucose-tolerance test is often done in borderline cases to determine if the individual is indeed diabetic.

A blood test called glycohemoglobin is also helpful (see below). Since the late 1970s it has been routinely used to determine the average blood sugar in diabetics, and it may be used as an additional screening test when screening a potential diabetic.

Glucose-Tolerance Test

The glucose-tolerance test (GTT) is routinely used in diagnosing diabetes and hypoglycemia. However, in my opinion, use of the GTT is unnecessary in most cases, since either diabetes or hypoglycemia may be diagnosed from symptoms, physical findings, and other laboratory tests. With the GTT, after a twelve-hour fast, a sample of blood is taken to determine the fasting-glucose level. The individual then drinks a standardized sugar solution, and blood-sugar levels are measured for up to six hours. Many people subjected to this test become acutely ill and may feel poorly for as long as a few days.

A two-hour post-prandial blood-glucose determination is more useful. In this case, the individual comes to the laboratory for a blood glucose test two hours after completing a carbohydrate-rich meal. Although this test will also make many individuals feel poorly, approaching the diagnosis in this manner at least avoids putting the individual through the metabolic insult of the glucose tolerance test.

Evaluating Glycohemoglobin

Glycohemoglobin molecules form in the blood when glucose and hemoglobin combine. A normal number form when the average blood-sugar (glucose) level is normal. If glycohemoglobin is high, the average blood-sugar level is also correspondingly high. Thus a physician may periodically determine if a diabetic is adequately controlling his or her blood sugar. The test may also be routinely used in the initial evaluation of older individuals, or others in whom diabetes or borderline diabetes is suspected.

The glycohemoglobin test is of limited use in diagnosing hypoglycemia (low blood sugar); results are consistent in nonreactive hypoglycemia but inconsistent in reactive hypoglycemia. For both types, symptoms occur when blood sugar is low, but blood sugar in reactive hypoglycemia (hypoglycemia occurring in response to food) varies widely and may indeed at times be high.

As a result, average blood sugar and glycohemoglobin may be high, low, or average. In chronic, nonreactive hypoglycemia, blood sugar is nearly always low, and glycohemoglobin is thus low.

THYROID-HORMONE TESTING

A determination of thyroid-hormone levels is commonly ordered along with a CBC and a chemistry screen, particularly if the physician suspects under- or overactivity of the thyroid gland. The routine tests are called T₃ and T₄ (triiodothyronine and thyroxine), and while they may confirm a condition of myxedema (grossly underactive thyroid function) or thyrotoxicosis (grossly overactive thyroid function), these tests often show normal values in people suffering from chronic low-thyroid function.

T₃ and T₄ replaced the basal metabolism rate test in the 1950s as the standard laboratory procedure for evaluating thyroid function. Since then, researchers and clinicians have often emphasized in the medical literature that these tests may fail to adequately determine thyroid status and that the physician must primarily consider symptoms, signs, history, and physical findings (rather than laboratory results).

In my experience, hundreds of people in whom T₃ and T₄ tested normal suffered from conditions related to a chronically underactive thyroid gland. Though this is not the prevailing view of thyroid problems, it is an important one, well expressed by Dr. Broda Barnes in his 1975 book Hypothyroidism: The Unsuspected Illness. (Barnes’s work, and the evaluation and treatment of thyroid problems, were discussed in chapter 9.)