Laboratory values provide healthcare professionals with essential clues about the patient’s condition and the medical interventions needed for his full recovery. As nurses are the first-line responders to the healthcare needs of patients, we should always be familiar with the common laboratory values and how to interpret them.
I. Complete Blood Count.
Complete blood count is one of the most basic laboratory examinations to determine the status of the patient’s health. It can help diagnose conditions such as infections, autoimmune disorders, anemia and other blood diseases.
A. Red Blood Cell (RBC).
The red blood cells’ primary function is to carry oxygen in the bloodstream. If the total RBC count is below normal levels, anemia may be present. This may lead to insufficient supply of oxygen to the body.
On the other hand, if the total RBC count is above normal, polycythemia vera may be present. Too many red blood cells in the bloodstream tend to form clots and may cause blockage.
Male: 4.5–5.5 x 1012/L
Female: 4.0–5.0 x 1012/L
Children: 3.8–6.0 x 1012/L
Newborn: 4.1–6.1 x 1012/L
High Level: Dehydration, cigarette smoking, congenital heart disease, pulmonary fibrosis, renal cell carcinoma, polycythemia vera.
Low Level: Bleeding, anemia, malnutrition, overhydration, hemolysis, erythropoietin deficiency, leukemia, multiple myeloma, porphyria, thalassemia, sickle cell anemia.
Drugs that may increase RBC count: Methyldopa, gentamycin.
Drugs that may decrease RBC count: Quinidine, hydantoins, chloramphenicol, chemotherapeutic drugs.
B. Hemoglobin (Hgb).
Hemoglobin is the protein component of red blood cells. It makes the blood look bright red as it is made with iron.
High hemoglobin levels are usually present among people living in high altitude levels and among smokers. It’s the body’s compensatory mechanism in response to low supply of oxygen. On the other hand, low hemoglobin levels may be present in a variety of blood diseases like sickle cell disease and thalassemia.
Male: 140–174 grams per liter (g/L)
Female: 120–160 g/L
Children: 95–205 g/L
Newborn: 145–245 g/L
High Level: Dehydration, cigarette smoking, polycythemia vera, tumors, erythropoietin abuse, lung diseases, blood doping.
Low Level: Nutritional deficiencies, blood loss, renal problems, sickle cell anemia, bone marrow suppression, leukemia, lead poisoning, Hodgkin’s lymphoma.
Drugs that may increase hemoglobin: Erythropoietin, iron supplements.
Drugs that may decrease hemoglobin: Aspirin, antibiotics, sulfonamides, trimethadione, anti-neoplastic drugs, indomethacin, doxapram, rifampin and primaquine.
C. Hematocrit (Hct).
Hematocrit is also known as packed cell volume or PCV. It reflects the volume percentage of red blood cells in the whole blood. The result is dependent on the size, structure and total number of red blood cells. Determining hematocrit is helpful in diagnosing and assessing blood diseases, nutritional deficiencies and hydration status.
Male: 42% – 54%
Female: 38% – 46%
Children: 36% – 40%
Newborn: 55% – 68%
High Level: Dehydration, hypoxia, cigarette smoking, polycythemia vera, tumors, erythropoietin abuse, lung diseases, blood doping, erythrocytosis, cor pulmonale.
Low Level: Overhydration, nutritional deficiencies, blood loss, bone marrow suppression, leukemia, lead poisoning, Hodgkin’s lymphoma, chemotherapy treatment.
Drugs that may increase hemoglobin: Erythropoietin, iron supplements.
Drugs that may decrease hemoglobin: Aspirin, antibiotics, anti-neoplastic drugs.
D. Platelet Count.
Platelets are also known as thrombocytes. They circulate in the bloodstream and bind together to form a clot over the damaged blood vessel. Determining platelet count is vital in assessing patients for tendencies of bleeding and thrombosis.
150,000 to 400,000 per microliter.
High Level: Cancer, allergic reactions, polycythemia vera, recent spleen removal, chronic myelogenous leukemia, inflammation, secondary thombocytosis.
Low Level: Viral infection, aplastic anemia, leukemia, alcoholism, vitamin B12 and folic acid deficiency, systemic lupus erythematosus, hemolytic uremic condition, HELLP syndrome, disseminated intravascular coagulopathy, vasculitis, sepsis, splenic sequestration, cirrhosis.
Drugs that may increase platelet: Romiplostim, steroids, human IgG, immunosuppresants.
Drugs that may decrease platelet: Aspirin, hydroxyurea, anagrelide, chemotherapeutic drugs, statins, ranitidine, quinidine, tetracycline, vancomycin, valproic acid, sulfonamides, phenytoin, piperacillin, penicillin, pentoxifylline, omeprazole, nitroglycerin.
E. White Blood Cell.
White blood cells, also known as leukocytes, defend the body against infections and other foreign bodies. In general, there are five types of white blood cells – neutrophils, lymphocytes, monocytes, eosinophils and basophils. The total number of white blood cells is often used as indicator of bacterial and viral infections.
5,000 – 10,000 per microliter (Some textbooks say 4,500 – 10,000.)
High Level: Infections, cigarette smoking, leukemia, inflammatory diseases, tissue damage, severe physical or mental stress.
Low Level: Autoimmune disorders, bone marrow deficiencies, viral diseases, liver problems, spleen problems, severe bacterial infections, radiation therapy.
Drugs that may increase white blood cells: Corticosteroids, heparin, beta adrenergic agonists, epinephrine, granulocyte colony-stimulating factor, lithium.
Drugs that may decrease white blood cells: Diuretics, chemotherapeutic drugs, histamine-2 blockers, captopril, anticonvulsants, antibiotics, antithyroid drugs, quinidine, chlorpromazine, terbinafine, clozapine, sulfonamides, ticlopidine.
Urinalysis is usually done as part of routine diagnostic examinations. Although the result of urinalysis cannot directly pinpoint the disease that may be present, it is often used as a supportive examination in diagnosing illnesses. A standard urinalysis involves three stages – visual exam, dipstick test and microscopic exam.
A. Visual Examination.
In visual examination, the urine sample is inspected for color, cloudiness and odor. Urine is usually clear but its color may be affected by certain medications and foods. If cloudiness and unpleasant odor are present, there might be infection in the urinary tract system. Here are some indications of different colors of urine:
- Clear to dark yellow – normal.
- Amber to honey yellow – dehydration.
- Orange – dehydration, intake of rifampicin, consumption of orange food dye.
- Brown ale – severe dehydration, liver disease.
- Pink to reddish – consumption of beets, rhubarb or blueberries, mercury poisoning, tumors, kidney diseases, prostate problems, UTI.
- Blue or green – consumption of asparagus, genetic disorders, excess calcium, heartburn medications, multivitamins.
- Deep purple – porphyria.
B. Dipstick Urine Test.
The dipstick urine test is done by dipping a plastic strip into the urine sample. This strip has partitions impregnated by different chemicals that correspond to certain substances present in the urine, so abnormalities will be detected.
Once the strip is dipped into the urine, there will be some changes in the color of the partitions. The following are the chemical tests usually included in reagent strips:
The pH level of the urine is related to the acid-base balance maintained by the body. Therefore, consumption of acidic or basic foods as well as the occurrence of any condition in the body that produces acids or bases will directly affect the pH of the urine. In some circumstances, too acidic or basic urine produces crystals. When this phenomenon happens inside the kidney, kidney stones can develop.
- Specific Gravity
Specific gravity reflects how concentrated the urine is. It can measure the proportion of solutes present in the urine when compared to pure water. Determining specific gravity is useful when you want to detect a particular substance in the urine sample. For example, if you suspect that a patient secretes small amounts of protein in the urine, the first morning-void urine is the best sample because it has high specific gravity and appears concentrated.
Albumin is usually the first type of protein compound excreted in the urine whenever there is a kidney problem. Other types of protein compounds are not detectable in dip stick test and can be measured through a different urine protein test. Conditions that usually produce high amounts of protein in the urine include preeclampsia, multiple myeloma, inflammation, urinary tract injuries, malignancies and other disorders that destroy red blood cells.
Glucose should not be present in the urine. However, in some circumstances the renal threshold allows the excretion of glucose in the urine when the blood glucose levels are too high. The conditions that can cause glucosuria are pregnancy, diabetes mellitus, liver diseases and hormonal disorders.
Like glucose, ketones should not be present in the urine. Ketones are by-products of fat metabolism and they form whenever there is not enough carbohydrates present for energy production. Ketones also form when insulin levels are not enough to initiate carbohydrate metabolism so the body just uses fat in order to produce the energy needed for daily activities. Other conditions that produce ketones in the urine are diabetes mellitus, frequent vomiting, strenuous exercise, and high protein diet.
The presence of blood in the urine is called hematuria and this usually happens when there is an injury in the urinary tract. Other conditions that may induce hematuria include cigarette smoking, strenuous exercise, kidney problems and trauma.
- Leukocyte Esterase
Leukocyte esterase is the enzyme produced by white blood cells. Normally, there are white blood cells present in the urine, but they are so few that there is no leukocyte esterase detectable in dip stick test.
On the other hand, when there are many white blood cells present in the urine the leukocyte esterase level elevates and it could be detected in strips. White blood cells in the urine increase in response to urinary tract infections.
Bilirubin is a part of bile which is the yellow fluid secreted into the intestines to aid in digestion. Bilirubin is a waste product produced by the liver. It should not be present in a normal urine sample but once detected, it can reflect the presence of liver diseases.
Urobilinogen is formed from bilirubin. It is excreted in the urine in small amounts. High urobilinogen levels in the urine can signify liver diseases and other conditions that can cause RBC destruction. For people with liver problems and obvious signs of liver dysfunction, the absence of urobilinogen may indicate the presence of hepatic or biliary obstruction.
When bacterial infection is present in the urinary tract, the bacterial flora can convert the urine’s nitrate compound to nitrite. However, the detection of nitrite in the urine is not used as a sole basis for the determination of UTI as some people can still have UTI with a negative nitrite result.
C. Microscopic Examination.
In microscopic examination, the urine sample is centrifuged so sediments will settle at the bottom and the clear part can be discarded. Few drops of this centrifuged urine will be examined under microscope. The sediments observed under the microscope are measured in terms of per lower power field (LPF) or per high power field (HPF).
Some other entities are also measured by estimations like “few”, “many” or “moderate”. The following are the entities measured in microscopic examination:
- Red blood cells (RBCs)
RBCs are present in the urine sample of a person with severe urinary tract infection, renal disorders, urinary tract injuries and inflammation. It can also reflect improper collection of urine specimen (e.g. Urine contaminated by blood from menstruation or hemorrhoids).
- White blood cells (WBCs)
Elevated WBCs in the urine signify infection or inflammation of the urinary tract. It can also reflect improper urine sample collection as in the case of urine specimen contaminated by vaginal secretions.
- Epithelial cells
In a normal urine specimen, there are few epithelial cells that can be seen under microscopic examination. However, in cases of severe urinary tract infection, inflammation and malignancies, there will be increased number of epithelial cells in the urine. Elevated number of epithelial cells can also signify improper collection of urine specimen, especially if it is not collected using the midstream-catch technique.
Normal urine sample is ideally sterile and free from microorganisms. However, in cases of urinary tract infection and improper urine collection, microorganisms such as bacteria, yeast and trichomonads can be found under microscopic examination. Results should be correlated clinically as these microorganisms are also present externally in the genitals.
Casts are cylindrically shaped particles formed from coagulated protein secreted by renal cells. In normal circumstances, these casts are clear and called “hyaline” casts. When there are kidney problems present, the casts have different components inside like RBCs or WBCs. Examples include fatty casts, granular cast, and waxy casts among others.
Crystals can be formed from the solutes of the urine especially if the urine is concentrated or when the pH is too high or too low. Examples of casts that are not typically present in the urine include leucine, cystine and tyrosine. These casts may signify malignancies and abnormal metabolic processes.
III. Serum Electrolytes.
Potassium is critical in nerve and muscle function. Nerves and muscles communicate impulses through the help of potassium in the blood. The movement of nutrients into the cell and the transport of waste products out of the cell are also mediated by potassium. Whenever potassium levels are increased or decreased, the heart rhythms are affected as signified by EKG changes.
3.5 – 5.0 milliequivalents per liter (mEq/L).
High Level: Infection, dehydration, Addison’s disease, injury to tissue, diabetes, acute or chronic kidney failure, hypoaldosteronism.
Low Level: Anorexia nervosa, malnutrition, diarrhea, vomiting, poorly managed diabetes, hyperaldosteronism.
Drugs that may increase potassium: ACE inhibitors, beta blockers, NSAIDs, potassium-sparing diuretics.
Drugs that may decrease potassium: Amphotericin B, gentamicin, carbenicillin, corticosteroids, beta-adrenergic agonists, potassium-wasting diuretics.
Sodium reflects a part of renal function as kidneys are responsible for the elimination of sodium from the body. It also plays a part in motor and nerve function. Patients are tested for serum sodium levels in cases of dehydration, edema, abnormal blood pressure levels and changes in motor functions.
135 to 145 milliequivalents per liter (mEq/L).
High Level: Cushing syndrome, diabetes insipidus, excessive fluid loss, malnutrition, dehydration.
Low Level: Addison’s disease, renal diseases, cirrhosis, heart failure, ketonuria.
Drugs that may increase sodium: NSAIDs, laxatives, birth control pills, corticosteroids and lithium.
Drugs that may decrease sodium: Diuretics, morphine, and SSRI antidepressants.
Together with sodium, potassium and carbon dioxide, chloride maintains the normal acid-base balance of the body through balancing body fluids. Abnormal changes in serum chloride levels usually reflect metabolic changes in the body.
96 – 106 milliequivalents per liter (mEq/L).
High Level: Diarrhea, metabolic acidosis, compensated respiratory alkalosis, renal tubular acidosis, bromide poisoning, kidney diseases, Cushing syndrome, hyperventilation.
Low Level: Vomiting, burns, excessive sweating, dehydration, gastric suction, chronic lung diseases, Addison’s disease, Bartter syndrome, congestive heart failure, metabolic alkalosis, compensated respiratory acidosis, hyperaldosteronism, syndrome of inappropriate diuretic hormone secretion (SIADH).
Drugs that may increase chloride: Carbonic anhydrase inhibitors.
Drugs that may decrease chloride: Diuretics.
Calcium is usually binded with protein in the blood. For this reason, a standard calcium test can be misleading and determination of ionized calcium is recommended. The ionized calcium test measures the calcium that is not attached to proteins. Determining serum calcium levels is important when there are existing nerve and motor dysfunctions.
8.5 to 10.2 mg/dL.
High Level: Tuberculosis, fungal and mycobacterial infections, HIV/AIDS, hyperparathyroidism, metastatic bone tumor, Paget’s disease, multiple myeloma, osteomalacia, sarcoidosis, hyperthyroidism.
Low Level: Malnutrition, vitamin D deficiency, hypoparathyroidism, low blood level of albumin, kidney failure, magnesium deficiency, liver disease, osteomalacia, pancreatitis.
Drugs that may increase calcium: Lithium, tamoxifen, thiazides, calcium supplements, vitamin D supplements.
Drugs that may decrease calcium: No known drug.
Magnesium is important in muscle and nerve functions, blood pressure regulation and immune system. It also plays a role in blood sugar regulation.
Although half of magnesium in the body is stored in bones, magnesium can also be found in cells of organs and body tissues. Magnesium levels are determined whenever there are changes in motor functions or when patients are suspected for metabolic diseases.
1.7 to 2.2 mg/dL
High Level: Oliguria, dehydration, Addison disease, chronic renal failure, diabetic acidosis.
Low Level: Chronic diarrhea, alcoholism, hemodialysis, ulcerative colitis, delirium tremens, hypoparathyroidism, hyperaldosteronism, hepatic cirrhosis, pancreatitis, toxemia of pregnancy.
Drugs that may increase magnesium: Milk of magnesia, lithium carbonate.
Drugs that may decrease magnesium: Insulin, antiarrhythmic drugs, digoxin amiodarone, sotalol, quinidine, bretylium, strophanthin, diuretics, isoproterenol.
Phosphorus is involved in the intracellular metabolism of proteins, fats and carbohydrates. It also participates in the production of ATP which is the chemical compound that supplies energy to the cell.
Phosphorus plays an important role in acid-base balance of the body and in glycolysis. It also helps in the release of oxygen molecule from the hemoglobin of the blood.
2.4 to 4.1 mg/dL
High Level: Hypoparathyroidism, diabetic ketoacidosis, liver disease, kidney failure.
Low Level: Poor nutrition, alcoholism, hyperparathyroidism, hypercalcemia .
Drugs that may increase phosphorous: Vitamin D, phosphate-containing laxatives.
Drugs that may decrease phosphorous: Antacids, diuretics, corticosteroids, anticonvulsants, ACE inhibitors, insulin.
IV. Renal Function Tests.
A. Blood Urea Nitrogen (BUN).
BUN is a by-product of protein metabolism. This test is used to determine the adequacy of renal function but it may also produce false-positive result as it is dependent on renal blood flow, protein metabolism, catabolism, drugs and diet.
BUN can also reflect protein tolerance, hydration status, degree of catabolism and risk of uremic syndrome.
6 – 20 mg/dL
High Level: Hypovolemia, excessive protein levels in the gastrointestinal tract, congestive heart failure, gastrointestinal bleeding, heart attack, urinary tract obstruction, glomerulonephritis, pyelonephritis, acute tubular necrosis, kidney failure, shock.
Low Level: Low protein diet, malnutrition, liver failure, fluid overload.
Drugs that may increase BUN: Allopurinol, furosemide, indomethacin, cisplatin, methyldopa, propanolol, tetracyclines, rifampin, vancomycin, thiazide diuretics, gentamycin, carbamazepine, aminoglycosides, amphotericin B.
Drugs that may decrease BUN: Streptomycin, chloramphenicol.
Creatinine is the product of muscle metabolism. Whenever there is an elevation in serum creatinine levels, renal dysfunction is usually suspected since the kidneys are responsible for the excretion of creatinine in the body. In general, creatinine levels vary depending on a person’s body size and muscle mass.
Men: 0.7 to 1.3 mg/dL
Women: 0.6 to 1.1 mg/dL
High Level: Preeclampsia, dehydration, renal problems, rhabdomyolysis, blocked urinary tract, myasthenia gravis, hyperthyroidism, muscular dystrophy.
Low Level: Spinal cord injuries, cachexia, sudden decrease in activity.
Drugs that may increase creatinine: Aminoglycosides, methicillin, amphotericin B, cistplatin, dextran,cyclosporine, gallium, lithium, hydroxyurea, methoxyflurane, nitrofurantoin, plicamycin, pentamidine, streptozocin.
Drugs that may decrease creatinine: Neuromuscular blocking agents.
About the Author: Je Abarra is a nurse by profession and a freelance writer by passion. She is working as a staff nurse in the pediatric ward of a private city hospital for more than two years. During her free time, she usually writes about her fascinations in health and nursing. She loves to provide tips and fun facts about nursing and healthy living.