Blood Chemistry

Northwestern Mutual's Blood Chemistry Profile is a group of tests performed on a single sample of blood. Each test measures the value of a different substance in the blood. These values provide information on the function of different organ systems (kidney, liver, etc.) or the risk for certain diseases (diabetes mellitus, coronary heart disease, etc.). Northwestern Mutual's Blood Chemistry Profile screens consist of 17 tests separated into five different groups on a functional basis. These groups and their functions are listed below:

Diabetes mellitus: Glucose, Hemoglobin AIC
Kidney disorders: BUN, Creatinine
Liver disorders: Bilirubin, AP, AST, ALT, GGT
Blood lipids: Cholesterol, LDL Cholesterol, HDL Cholesterol, Chol/HDL Chol Ratio, Triglycerides
Blood proteins: Total Protein, Albumin, Globulin

Blood Chemistry Profile

Diabetes mellitus

Diabetes Mellitus is a disorder of the body's metabolism the process by which food is transformed into energy. Most of our digested food is broken down into glucose, a sugar which is the body's main source of energy. The bloodstream carries glucose to the body's cells to be used as a source of energy. For glucose to enter cells, insulin must be present.

Insulin is a hormone produced by the pancreas. When food is digested, the pancreas automatically produces enough insulin to move glucose from the bloodstream into cells where it can be utilized. In persons with Diabetes Mellitus, the pancreas produces little or no insulin or the cells do not respond appropriately to the insulin that is produced.

Diabetes Mellitus resulting from the pancreas producing little or no insulin is known as Type I Diabetes. Diabetes resulting from resistance to insulin's effect and defective insulin production is known as Type 2 Diabetes.

Tests

The diagnosis of Diabetes Mellitus depends on the measurement of blood glucose levels. Blood glucose fluctuates in response to ingestion of food. Blood glucose will be higher 1 to 2 hours after a meal than it will be 8 to 10 hours after a meal. Based on extensive studies, normal ranges for blood glucose levels have been established. Blood glucose levels which exceed these ranges are abnormal and said to be elevated. The risk for Diabetes Mellitus increases the further the blood glucose elevation falls outside of the normal range.

A fasting blood glucose is the most commonly used screen for Diabetes Mellitus. It measures blood glucose after a set period of time since the last ingestion of food. Occasionally, an oral glucose tolerance test is also necessary. This measures glucose levels at timed intervals over a 3-hour period following the ingestion of a prescribed amount of glucose.

Once blood glucose reaches levels of 180 or higher, glucose can be detected in the urine. However, some persons will spill glucose in their urine even when blood glucose levels are within normal limits. The finding of glucose in the urine should be evaluated with a blood glucose measurement.

Northwestern Mutual utilizes blood glucose as an initial screen for Diabetes Mellitus. Depending on the value of the blood glucose, a hemoglobin A1C may also be measured. Hemoglobin A1C reflects a person's average blood glucose level for the preceding 2 to 3 months. Diabetes Mellitus cannot be diagnosed on the basis of one set of abnormal tests. Abnormal results are best interpreted by a person's personal physician.

It is not the intention of Northwestern Mutual to provide specific medical advice, but rather to provide users with information to better understand their health. Please consult with a qualified physician for diagnosis and for answers to your personal questions.

Kidney disorders

The primary role of the kidneys is to remove waste and excess fluid from the bloodstream. When the kidney's filtering function is compromised, dangerous amounts of waste and fluids accumulate in the body. This condition is called kidney or renal failure. Renal failure can be divided into two types: acute and chronic.

Acute renal failure occurs when the kidney's filtering capacity is suddenly and dramatically reduced over a period of days to weeks. Chronic renal failure on the other hand evolves in a much slower manner typically over many years. Chronic renal failure may remain asymptomatic until more than 75% of the kidney's function has been lost. It is estimated that as many as 20 million American adults have chronic renal failure and another 20 million are at risk for developing it. In the United States, the two leading causes of chronic renal failure are diabetes mellitus and hypertension.

Tests

Normally functioning kidneys remove waste from the bloodstream. Blood levels of certain waste products are commonly used as indicators that the kidneys are functioning normally. When the kidney's filtration function is compromised, waste products accumulate in the blood. Two waste products commonly used to assess kidney (renal) function are urea and creatinine. Based on extensive studies of persons with normal kidney function "usual clinical ranges" have been established for both these substances. Blood levels higher than the usual clinical range may be a sign that the kidneys are not functioning properly.

Blood urea nitrogen (BUN) is a measure of the level of urea present in the blood. Urea is a waste product produced from the breakdown of food protein. BUN elevation is not specific for kidney dysfunction but can be influenced by non-kidney related factors such as the protein content of a person's diet and state of hydration.

Creatinine is a waste product from meat protein in the diet and normal muscle function. Creatinine levels are less likely to be influenced by diet and non-kidney related factors. The simultaneous elevation of BUN and creatinine beyond the usual clinical ranges is most suggestive of possible abnormal renal function.

Liver disorders

The liver is the largest organ in the human body. The liver can best be described as a complex chemical factory which performs many functions that are essential for life. A few of these include: changing food into energy, clearing alcohol and poisons from the blood and producing chemicals that the body needs for proper functioning. There are many diseases that can affect the liver. Common among these diseases are various forms of "hepatitis."

Hepatitis is a general term that denotes "inflammation" or "irritation" of the liver. Hepatitis can result from infection (viral hepatitis), chemicals or drugs (toxic hepatitis) or immunologic abnormalities (autoimmune hepatitis). Sometimes hepatitis resolves in a matter of weeks to months with little or no permanent damage to the liver. However if the inflammation last for six months or longer, it is known as chronic hepatitis.

Chronic hepatitis, like multiple other liver disorders, can exist for many years in the absence of symptoms. These disorders can remain undetected until the liver is severely damaged. Hepatitis C and hemochromatosis are just two examples.

Tests

Four enzymes and bilirubin are used to screen for possible liver disease.

Enzymes are proteins which facilitate chemical reactions within the body's cells. The types of enzymes within body cells vary greatly by their function and organ location. Alkaline Phosphatase (AP), Aspartate Aminotransferase (SGOT, AST), Alanine Aminotransferase (SGPT, ALT) and Gamma Glutamyl Transferase (GGT) are enzymes present in the liver cells in increased amounts. When the liver is injured, one or more of these enzymes can be released by the damaged cells causing an elevation in their blood level(s).

Many liver disorders cause damage slowly over many years in the absence of symptoms or loss of function. AP, AST, ALT and/or GGT elevations can be the only indication of a previously unrecognized chronic liver disease. Blood levels of one or more of these enzymes above the usual clinical range suggest the possibility of a liver disorder. This possibility is increased with greater elevations. For example, an enzyme elevation which is more than three times the usual clinical range is more suggestive of a liver disorder than an enzyme elevation which is less than twice the usual clinical range. Similarly, multiple enzyme elevations increase the possibility of a liver disorder.

AP, AST, ALT and GGT elevations are suggestive but not specific for liver disease. GGT elevation can also result from prolonged, excessive alcohol use. The significance of any enzyme elevation is best determined in the context of your personal medical history. Your personal physician is the best judge of the need for repeat or additional laboratory studies. Chronic viral hepatitis caused by either the hepatitis B or C virus is a significant cause of chronic liver disease in the United States. ALT elevation is more specific for liver damage caused by chronic viral hepatitis. Northwestern Mutual automatically screens blood chemistry profiles with ALT elevations for evidence of exposure to the hepatitis B and C virus.

Bilirubin is a breakdown product of hemoglobin produced in the liver and excreted in the bile. Elevated bilirubin can result from excessive red blood cell breakdown (hemolytic anemia), liver dysfunction or an obstructed bile duct. Minor elevations in bilirubin can be due to Gilbert's disease, an innocent disorder which affects 3-5% of the United States population. Like enzyme elevations, the significance of bilirubin elevation is best assessed by one's personal physician.

Bloods lipids

The 2 main lipids (or fats) in the blood are cholesterol and triglyceride. Cholesterol is essential to both the structure and function of the body's cells. Cholesterol is an important component of cell membranes as well as a building block for certain types of hormones. Triglycerides are important in the transfer of the energy derived from food into cells.

If too much cholesterol is present in the blood over many years, it can accumulate in the walls of the arteries that supply blood to the heart and the brain. Together with other substances, a hard deposit forms in the blood vessel wall. These fatty deposits are called plaques and this condition is known as atherosclerosis. The plaques over time enlarge causing narrowing of the arteries and can eventually compromise the blood supply to the heart, brain and other vital organs. Elevated triglyceride levels are also felt to increase the risk for the development of atherosclerosis.

Atherosclerosis affecting the artery supplying heart muscle (coronary artery disease) increases the risk of a heart attack. Similarly, atherosclerosis affecting the blood vessels which supply the brain increases the risk of a stroke. Elevated cholesterol is one factor among several which should be considered when assessing the overall risk for the development of atherosclerosis. Other significant factors would include family history, build, tobacco use and high blood pressure.

Tests

Cholesterol and other fats (lipids) have to be transported in the blood attached to a protein. These combinations are called lipoproteins. Lipoproteins are categorized by the ratio of lipid content to protein content. Protein is more dense than lipid. High-density lipoprotein (HDL) contains more protein than lipid. Low-density lipoprotein (LDL) contains more lipid than protein. The risk for atherosclerosis depends on both the type and degree of cholesterol elevation. LDL elevation increases the risk for atherosclerosis in proportion to its elevation beyond normal limits. Conversely, HDL elevation decreases the risk for atherosclerosis. For this reason, HDL is sometimes referred to as "good cholesterol" and LDL as "bad cholesterol". The ratio of total cholesterol and HDL is another factor used to assess the risk for atherosclerosis based on lipid profiles. Ratios of 4 or less are more favorable.

Abnormal lipid studies and other possible risk factors for atherosclerosis should be discussed with your personal physician.

Blood proteins

The blood contains two major groups of protein: Albumin and Globulin. Albumin is made in the liver and makes up approximately 60% of the total protein. Since Albumin is produced in the liver, it is used as a measure of liver function as well as overall nutrition. One of the key functions of albumin is to prevent the abnormal movement of fluid from the bloodstream into the body's tissues. In addition, Albumin helps to transport medications and other substances through the blood.

Globulin is made up of several different types of protein. Globulin can be divided into three main groups: alpha-, beta- and gammaglobulin. Gammaglobulins are antibodies. Antibodies are proteins produced by the immune system to fight infection.