Lab tests, along with a health history and physical exam, are used by physicians to diagnose and manage health conditions. When your body is healthy, it functions normally in a state of homeostasis or equilibrium. When your body is in homeostasis, the values for fluids, chemicals, electrolytes, and secretions (hormones) are typically within an acceptable or “normal” range. When you have a pathologic condition (e.g. a disease state), these ranges can change as a result of an imbalance in your body. The disease can cause the imbalance, and vice versa, the imbalance may cause the disease. Lab tests can help identify these imbalances which will aid the medical professional in understanding and treating the underlying problem.
Furthermore, if you are on medications, lab tests and lab profiles can also be used to determine the exact amount of medicine that you should be taking to appropriately treat your condition. The normal range of values for lab tests are established and acceptable values within which the test results for a healthy person are expected to fall.
Lab Tests and Values
| Test | Normal Values |
|---|---|
| Albumin, serum | 3.5 – 5.5 g/dL |
| ALT | 45 U/L or less |
| AST | 40 U/L or less |
| Bilirubin, total | 1.2 – 1.3 mg/dL or less |
| Blood group (A,B,O) | |
| BUN, serum | 7-25 mg/dL |
| Calcium, serum | 8.5 – 108 mg/dL |
| CBC with differential | values given with report |
| Chloride, serum | 96-109 mmol/L |
| CPK | male: 17 – 148 U/L, female: 10 – 70 U/L |
| Creatinine, serum | 0.6 – 6 mg/dL |
| CRP | 0.8 mg/dL or less |
| Glucose, plasma | 70-110 mg/dL |
| LDH | less than 240 U/L |
| Potassium, serum | 3.5 – 5.3 mmol/L |
| Prothrombin time | 9 – 12 seconds |
| Rapid plasma reagin | nonreactive |
| Sedimentation rate | male: 0 – 15 mm/hr, female: 0 – 20 mm/hr |
| Sodium, serum | 135 – 147 mmol/L |
| Triiodothyronine (T3) | 85 – 205 mg/mL |
| Thyroxine (T4) | 4.5 – 12 mg/dL |
| Total protein, serum | 6 – 8.5 g/dL |
| Triglycerides | less than 150 mg/dL |
| Uric acid, serum | male: 3.9 – 9 mg/dL, female: 2.2 – 7.7 mg/dL |
| Urinalysis, routine | |
Lab Profiles
Lab profiles are groups of test that are targeted at a certain organ or disease process. A profile may be ordered where your doctor does not have a specific clinical diagnosis for your condition. A profile can assess and diagnosis a condition. For example, a kidney profile can assess the function of your kidneys. The following is a list of lab profiles, tests included in the profile and how the results of the profile is used.
| Profile | Tests included | Profile Use |
|---|---|---|
| Comprehensive Metabolic Profile | Albumin, ALP, ALT, AST, bilirubin, BUN, calcium, carbon dioxide, chlorine, creatinine, glucose, potassium, sodium, total protein | General halth screen that gives information on the kidneys, liver, acid-base balance, blood glucose level, and blood proteins. It’s used to evaluate organ function and check for conditions like diabetes, liver disease, and kidney disease. It is routinely ordered as part of blood workup for physical examination or medical exam especially one where symptoms are vague. Abnormal test results are then followed up with more specific tests before a final diagnosis is made. |
| Electrolyte Profile | carbon dioxide, chloride, potassium, sodium | Screening for electrolyte or acid-base imbalance and to monitor the effects of treatment on a disease or condition that causes an electrolyte imbalance. This profile is also used to evaluate people taking medicines that can cause an electrolyte imbalance. |
| Hepatic Profile | Albumin, ALP, ALT, AST, direct bilirubin, total bilirubin, total protein | This profile is used to detect pathologic conditions of the liver. It is often ordered for symptoms such as jaundice, dark urine, light-colored bowel movements, or pain or swelling in the abdomen that indicate liver conditions. This profile may be ordered when someone has been exposed to hepatitis, has a family history of liver disease, has a history of excessive alcohol consumption or was taking medicine that can result in liver damage. |
| Hepatitis Profile | HBsAg, anti-HBc IgM, anti-HAV IgM | This profile is used to detect viral hepatitis. |
| Kidney Function Profile | albumin, BUN, calcium, carbon dioxide, chloride, creatinine, phosphatase, potassium, sodium | Used to detect kidney problems. The profile shows how well the kidneys are functioning to remove excess fluid and waste. When problems are detected, diagnostic imaging test may be ordered to further evaluate symptoms and make a diagnosis. This profile may be ordered if you are on dialysis or a special diet for kidney disease or failure. |
| Lipid Profile | total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides, VLDL-cholesterol (calculation), total cholesterol/ HDL ratio (calculation) | Used to determine the risk of coronary artery disease. |
| Prenatal Profile | ABO grouping and Rh typing, antibody screen, CBC, HBsAg, rubella antibodies, syphilis serology | Used for screenings of prenatal mothers to assess for ongoing disease or potential problems during pregnancy. May be ordered during the first prenatal visit. |
| Rheumatoid Profile | rheumatoid factor, ESR, CRP, uric acid, ANA | Help with the diagnosis of rheumatoid arthritis and to help separate it from other types of arthritis and conditions with similar symptoms. This profile is also used to evaluate the severity of rheumatoid arthritis, to monitor the condition and its complications, and to assess response to various treatments. |
| Thyroid Function Profile | FTI, Thyroxine (T4), Triiodothyronine (T3) uptake | Detect conditions affecting the thyroid gland. |
Categories of Laboratory Tests
| Category | Definition and commonly performed tests |
|---|---|
| Hematology | Hematology is the science that deals with the study of blood and blood forming tissues. Lab analysis for hematology deals with examining blood for detecting abnormalities and includes areas such as blood cell counts, cellular morphology, clotting ability of blood, and identification of cell types.
|
| Clinical Chemistry | Laboratory analysis in clinical chemistry determines the amount of chemical substances present in body fluids, excreta, and tissues. For example blood, urine, and cerebrospinal fluid. The most commonly evaluated clinical chemistry is blood chemistry.
|
| Serology and Blood banking | Blood banking is serology deal with the study of antigen/antibody reactions and assessing the presence of disease or other potential pathologic substances.
|
| Urinalysis | Urinalysis is the physical, chemical, and microscopic analysis of urine. Tests for physical analysis of urine includes: Color, Appearance, and Specific Gravity. Tests included in chemical analysis are: pH, Specific gravity, Glucose, Protein, Ketones, Blood, Bilirubin, Urobilnogen, Nitrite, Leukocytes. Tests included in microscopic analysis of urine are: Red blood cells, White blood cells, Epithelial cells, Casts, Crystals |
| Microbiology | Microbiology is the scientific study of microorganisms. It includes the identification and categorization of pathogens present in specimens taken from the body (such as urine, blood, throat, sputum, wound, urethra, vagina, cerebrospinal fluid). The following are examples of infectious diseases diagnosed by identifying pathogens present in a specimen:
|
| Parasitology | Parasitology deals with the detection or presence of disease producing human parasites or their eggs present in specimens taken from the body (for example stool, vagina, blood). Examples of human diseases caused by parasites include:
|
| Cytology | In the lab, cytology deals with the detection or presence of abnormal cells. These tests include chromosomal studies and a Pap smear. |
| Histology | Histology is the microscopic study of form and structure of various tissues that make up living organisms. Lab analysis deals with the detection of diseased tissues and includes tissue and biopsy analysis. |
