Knowing the different normal lab values is an important step in making an informed clinical decision as a nurse. Diagnostic and laboratory tests are tools that provide invaluable insights and information about the patient. Lab tests are used to help confirm a diagnosis, monitor an illness, and the patient’s response to treatment.
In the NCLEX, some questions supply laboratory results with no indication of the normal lab levels so you’ll have to familiarize yourself with them. NCLEX will not give you values that are within the normal range. Questions will usually include critical lab values and it’s a matter of identifying if it’s within normal range or not.
Please note that laboratory values may vary from agency to agency.
- Download Free Normal Lab Values Cheat Sheet
- Phases of Diagnostic Testing
- Before the procedure
- During the procedure
- After the procedure
- Erythrocyte Studies Normal Lab Values
- Red Blood Cells [RBC] Normal Lab Values
- Hemoglobin [Hgb]
- Hematocrit [Hct]
- Red Blood Cell Indices
- Serum Iron [Fe]
- Erythrocyte Sedimentation Rate [ESR]
- Coagulation Studies Normal Lab Values
- Platelets [Pt], Mean Platelet Volume [MPV], Fibrinogen
- Bleeding Time Normal Lab Values
- D-Dimer Test
- Prothrombin Time, International Normalized Ratio [PT/INR]
- Activated Partial Thromboplastin Time [APTT]
- White Blood Cells and Differential
- White Blood Cells [WBC]
- Serum Electrolytes Normal Lab Values
- Serum Sodium [Na+] Normal Lab Values
- Serum Potassium [K+]
- Serum Chloride [Cl-]
- Magnesium [Mg]
- Serum Osmolality
- Serum Bicarbonate [HCO3-]
- Phosphorus [P]
- Total Calcium [Ca+], Ionized Calcium
- Renal Function Studies Normal Lab Values
- Serum Creatinine [Cr], Creatinine [Urine], and Creatinine Clearance [CrCl]
- Blood Urea Nitrogen [BUN]
- Liver Function Studies Normal Lab Values
- Alanine Aminotransferase [ALT]
- Aspartate Aminotransferase [AST]
- Bilirubin
- Albumin
- Ammonia
- Amylase
- Lipase
- Serum Protein
- Glucose Studies Normal Lab Values
- Fasting Blood Glucose
- Glucose Tolerance Test [GTT]
- Glycosylated Hemoglobin [HbA1c]
- Diabetes Mellitus Autoantibody Panel
- Lipoprotein Profile [Lipid Profile] Normal Lab Values
- Cardiac Markers and Serum Enzymes
- Creatine Kinase [CK]
- Myoglobin
- Troponin I and Troponin T
- Natriuretic Peptides
- HIV and AIDS Testing
- CD4+ T-cell counts
- Thyroid Studies Normal Lab Values
- Arterial Blood Gas [ABG] Normal Lab Values
- Hepatitis Testing
- Therapeutic Drug Monitoring Normal Lab Values
- How to Obtain a Blood Sample
- References and Sources
Download Free Normal Lab Values Cheat Sheet
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Phases of Diagnostic Testing
Diagnostic testing involves three phases: pretest, intratest, and post-test. Nurses have responsibilities for each phase of diagnostic testing.
Before the procedure
In the pretest, the main focus is on preparing the client for the diagnostic procedure. Responsibilities during pretest include:
- Assessment of the patient to assist in determining precautions.
- Preparation of the equipment and supplies needed.
- Preparation of a consent form, if required.
- Providing information and answering client questions about the procedure.
During the procedure
During intratest, the main focus is specimen collection and performing or assisting with certain diagnostic procedures. Additional responsibilities during intratest are:
- Use of standard precautions or sterile technique if necessary.
- Providing emotional support to the patient and monitoring the patient’s response during the procedure.
- Ensuring the correct labeling, storage, and transportation of the specimen.
After the procedure
During the last part of diagnostic testing, the nursing care revolves around observations and follow-up activities for the patient. For example, if a contrast media was injected during a CT scan, the nurse should encourage the patient to increase fluid intake to promote excretion of the dye. Additional responsibilities during post-test include:
- Compare the previous and current test results
- Reporting of the results to the appropriate members of the healthcare team.
Erythrocyte Studies Normal Lab Values
Here are the normal lab values related to erythrocyte studies which include hemoglobin, hematocrit, red blood cell count, serum iron, and erythrocyte sedimentation rate. Venous blood is used as a specimen for complete blood count [CBC] which is a basic screening test that is frequently ordered to give an idea about the health of a patient.
Red Blood Cells [RBC] Normal Lab Values
Red blood cells or erythrocytes transport oxygen from the lungs to the bodily tissues. RBCs are produced in the red bone marrow, can survive in the peripheral blood for 120 days, and are removed from the blood through the bone marrow, liver, and spleen.
Indications of RBC count:
- Helps in diagnosing anemia and blood dyscrasia.
Normal values for red blood cell count:
| Adult male | 4.7—6.2 ✕ 1012/L | 4.7—6.2 ✕ 106/mm3 |
| Adult female | 4.5—5.0 ✕ 1012/L | 4.5—5.0 ✕ 106/mm3 |
| Child | 3.5—5.5 ✕ 1012/L | 3.5—5.5 ✕ 106/mm3 |
| Newborn | 4.8—7.1 ✕ 1012/L | 4.8—7.1 ✕ 106/mm3 |
Hemoglobin [Hgb]
Hemoglobin is the protein component of red blood cells that serves as a vehicle for oxygen and carbon dioxide transport. It is composed of a pigment [heme] which carries iron, and a protein [globin]. The hemoglobin test is a measure of the total amount of hemoglobin in the blood.
Indications of hemoglobin count:
- Hemoglobin count is indicated to help measure the severity of anemia [low hemoglobin] or polycythemia [high hemoglobin].
- Monitor the effectiveness of a therapeutic regimen.
Normal and critical values chart for hemoglobin count:
| Adult male | 140—170 g/L | 14—17 g/dL |
| Adult female | 120—150 g/L | 12—15 g/dL |
| Pregnant | >110 g/L | >11 g/dL |
| Child | 95—150 g/L | 9.5—15 g/dL |
| Newborn | 140—240 g/L | 14—24 g/dL |
| Critical values | 200 g/L | 20.0 g/dL |
Hematocrit [Hct]
Hematocrit or packed cell volume [Hct, PCV, or crit] represents the percentage of the total blood volume that is made up of the red blood cell [RBC].
Normal and critical values for hematocrit count:
| Adult male | 0.42—0.52 | 42%—52% |
| Adult female | 0.35—047 | 35%—47% |
| Pregnant | >0.33 [>33%] | >33% |
| Child | 0.30—0.44 | 30—44% |
| Newborn | 0.44—0.64 | 44%—64% |
| Critical values | 0.60 | 60% |
Increased hematocrit levels may indicate:
- Burns
- Chronic obstructive pulmonary disease
- Congenital heart disease
- Dehydration
- Eclampsia
- Erythrocytosis
- Polycythemia Vera
- Severe dehydration
Decreased hematocrit levels may indicate:
- Anemia
- Bone marrow failure
- Hemoglobinopathy
- Hemolytic reaction
- Hemorrhage
- Hyperthyroidism
- Leukemia
- Liver cirrhosis
- Malnutrition
- Multiple myelomas
- Normal pregnancy
- Nutritional deficiency
- Rheumatoid arthritis
Red Blood Cell Indices
Red blood cell indicates [RBC Indices] determine the characteristics of an RBC. It is useful in diagnosing pernicious and iron deficiency anemias and other liver diseases.
- Mean corpuscular volume [MCV]: The average size of the individual RBC.
- Mean corpuscular hemoglobin [MCH]: The amount of Hgb present in one cell.
- Mean corpuscular hemoglobin concentration [MCHC]: The proportion of each cell occupied by the Hgb.
Normal Lab Values for RBC Indices are:
| Mean corpuscular volume [MCV] | 82—98 fL | 82—98 mm3 |
| Mean corpuscular hemoglobin [MCH] | 0.40—0.53 fmol/cell | 26—34 pg/cel |
| Mean corpuscular hemoglobin concentration [MCHC] | 320—360 g/L | 32—36 g/dL |
| Reticulocyte Count | 0.005—0.015 | 0.5%—1.5% of total RBCs |
Serum Iron [Fe]
Iron is essential for the production of blood helps transport oxygen from the lungs to the tissues and carbon dioxide from the tissues to the lungs.
Normal lab values for serum iron:
| Adult male | 12.5—31.3 µmol/L | 70—175 µg/dL |
| Adult female | 8.9—26.8 µmol/L | 50—150 µg/dL |
| Child | 8.9—21.5 µmol/L | 50—120 µg/dL |
| Newborn | 17.9—44.8 µmol/L | 100—250 µg/dL |
| Total iron—binding capacity [TIBC] | 41.2—65.7 µmol/L | 229—365 µg/dL |
| Transferrin | 2.15—3.75 g/L | 215—375 mg/dL |
Indication of serum iron:
- Helps in diagnosing anemia and hemolytic disorder.
Increased serum iron levels may indicate:
- Hemochromatosis
- Hemosiderosis
- Hemolytic anemia
- Hepatic necrosis
- Hepatitis
- Iron poisoning
- Lead toxicity
- Massive transfusion
Decreased serum iron levels:
- Chronic blood loss
- Chronic gastrointestinal blood loss
- Chronic hematuria
- Chronic pathologic menstruation
- Inadequate absorption of iron
- Iron deficiency anemia
- Lack of iron in the diet
- Neoplasia
- Pregnancy [late stages]
Nursing considerations for serum iron:
- Recent intake of a meal containing high iron content may affect the results.
- Drugs that may cause decreased iron levels include adrenocorticotropic hormone, cholestyramine, colchicine, deferoxamine, and testosterone.
- Drugs that may cause increased iron levels include dextrans, ethanol, estrogens, iron preparations, methyldopa, and oral contraceptives.
Erythrocyte Sedimentation Rate [ESR]
Erythrocyte sedimentation rate [ESR] is a measurement of the rate at which erythrocytes settle in a blood sample within one hour.
Normal lab values for erythrocyte sedimentation rate:
| Male | 85 years: | 0—29 mm/hour |
| Female | 85 years: | 0—41 mm/hour |
| Child | ≥ 2 years | 0—10 mm/hour |
Indication for Erythrocyte Sedimentation Rate:
- Assist in the diagnosis of conditions related to acute and chronic infection, inflammation, and tissue necrosis or infarction.
Increased ESR levels may indicate:
- Bacterial infection
- Chronic renal failure
- Hyperfibrinogenemia
- Inflammatory disease
- Macroglobulinemia
- Malignant diseases
- Severe anemias such as vitamin B12 deficiency or iron deficiency
Decreased ESR levels may indicate:
- Hypofibrinogenemia
- Polycythemia vera
- Sickle cell anemia
- Spherocytosis
Nursing consideration
- Fasting is not required
- Fatty meal prior extraction may cause plasma alterations
Coagulation Studies Normal Lab Values
Physicians order coagulation studies such as platelet count, activated partial thromboplastin time, prothrombin time, international normalized ratio, bleeding time, and D-dimer to evaluate the clotting function of an individual. In this section, we’ll discuss the indications and nursing implications of each lab test.
Platelets [Pt], Mean Platelet Volume [MPV], Fibrinogen
Platelets are produced in the bone marrow and play a role in hemostasis. Platelets function in hemostatic plug formation, clot retraction, and coagulation factor activation.
Normal and critical values for platelet count and mean platelet volume:
| Adult | 150—400 ✕ 109/L | 150,000—400,000/mm3 |
| Child | 150—400 ✕ 109/L | 150,000—400,000/mm3 |
| Infant | 200—475 ✕ 109/L | 200,000—475,000 mm3 |
| Premature infant | 100—300 ✕ 109/L | 100,000—300,000/mm |
| Newborn | 150—300 ✕ 109/L | 150,000—300,000/mm3 |
| Critical values | 1,000 ✕ 109/L | 1 million/mm3 |
| Mean Platelet Volume [MPV] | 7.4—10.4 fL | 7.4—10.4 mm3 |
Normal and critical values for fibrinogen:
| Adult | 200–400 mg/dL |
| Newborn | 125–300 mg/dL |
| Critical value | 20 seconds |
Normal and Critical Lab Value for International Normalized Ratio [INR]
The INR standardizes the PT ratio and is calculated in the laboratory setting by raising the observed PT ratio to the power of the international sensitivity index specific to the thromboplastin reagent used.
| Normal | 0.8—1.2 |
| Therapeutic INR range for patients on warfarin | 2.0—3.0 |
| Therapeutic INR range for patients with mechanical heart valves | 3.0—4.0 |
| Critical value | >5.0 |
Increased prothrombin time may indicate:
- Bile duct obstruction
- Coumarin ingestion
- Disseminated intravascular coagulation
- Hepatitis
- Hereditary factor deficiency
- Liver cirrhosis
- Massive blood transfusion
- Salicylate intoxication
- Vitamin K deficiency
Decreased prothrombin time may indicate:
- Blood clots
quickly due to:
- Supplements containing vitamin K
- High intake of foods that contain vitamin K, such as liver, broccoli, kale, turnip greens and soybeans
Nursing Care for Prothrombin Time
- If a PT is prescribed, the baseline specimen should be drawn before anticoagulation therapy is started; note the time of collection on the laboratory form.
- Provide direct pressure to the venipuncture site for 3 to 5 minutes.
- Concurrent warfarin therapy with heparin therapy can lengthen the PT for up to 5 hours after dosing.
- Diets high in green leafy vegetables can increase the absorption of vitamin K, which shortens the PT.
- Orally administered anticoagulation therapy usually maintains the PT at 1.5 to 2 times the laboratory control value.
- Initiate bleeding precautions, if the PT value is longer than 30 seconds in a client receiving warfarin therapy.
Activated Partial Thromboplastin Time [APTT]
Activated partial thromboplastin time [APTT] evaluates the function of the contact activation pathway and coagulation sequence by measuring the amount of time it requires for recalcified citrated plasma to clot after partial thromboplastin is added to it. The test screens for deficiencies and inhibitors of all factors, except factors VII and XIII.
Normal and critical lab values for activated partial thromboplastin time [aPTT] and partial thromboplastin time [PTT]:
| Normal | 30—40 seconds | 60—70 seconds |
| Patients receiving anticoagulant therapy | 1.5—2.5 times control value [60—80 seconds] | 1.5—2.5 seconds times control value [120—140 seconds] |
| Critical values | none or >70 seconds | none or >100 seconds |
Indication for APTT:
- Monitors the effectiveness of heparin therapy.
- Detect coagulation disorders in clotting factors such as hemophilia A [factor VIII] and hemophilia B [factor IX].
- Determine individuals who may be prone to bleeding during invasive procedures.
Increased APTT levels may indicate:
- Congenital clotting factor deficiencies
- Disseminated intravascular coagulation
- Hemophilia
- Heparin administration
- Hypofibrinogenemia von Willebrand’s disease
- Leukemia
- Liver cirrhosis
- Vitamin K deficiency
Decreased APTT levels may indicate:
- Early stages of disseminated intravascular coagulation
- Extensive cancer
Nursing consideration for APTT:
- Do not draw samples from an arm into which heparin is infusing.
- If the client is receiving intermittent heparin by intermittent injection, plan to draw the blood sample 1 hour before the next dose of heparin.
- Apply direct pressure to the venipuncture site.
- Blood specimen should be transported to the laboratory immediately.
- The aPTT should be between 1.5 and 2.5 times normal when the client is receiving heparin therapy.
- Monitor for signs of bleeding if the aPTT value is longer than 90 seconds in a patient receiving heparin therapy.
White Blood Cells and Differential
The normal laboratory value for WBC count has two components: the total number of white blood cells and differential count.
White Blood Cells [WBC]
White blood cells act as the body’s first line of defense against foreign bodies, tissues, and other substances. WBC count assesses the total number of WBC in a cubic millimeter of blood. White blood cell differential provides specific information on white blood cell types:
- Neutrophils are the most common type of WBC and serve as the primary defense against infection.
- Lymphocytes play a big role in response to inflammation or infection.
- Monocytes are cells that respond to infection, inflammation, and foreign bodies by killing and digesting the foreign organism [phagocytosis].
- Eosinophils respond during an allergic reaction and parasitic infections.
- Basophils are involved during an allergic reaction, inflammation, and autoimmune diseases.
- Bands are immature WBCs that are first released from the bone marrow into the blood.
Normal and critical lab values for white blood cell count:
| Adult | 5.0—10 ✕ 109 cells/L | 5000—10,000/mm3 |
| Child [≤2 years] | 6.2—17 ✕ 109 cells/L | 6,200—17,000/mm3 |
| Newborn | 9.0—30 ✕ 109 cells/L | 9,000—30,000/mm3 |
| Critical values | 2.0—40 ✕ 109 cells/L | 40,000/mm |
Normal lab values for WBC differential:
| Neutrophils | 2,500—8,000/mm3 | 55—70% |
| Lymphocytes | 1,000—4,000/mm3 | 20—40% |
| Monocytes | 100—700/mm3 | 2—8% |
| Eosinophils | 50—500/mm3 | 1—4% |
| Basophils | 25—100/mm3 | 0.5—1% |
| Bands | 0—700/mm3 | 0—2% |
Increased WBC count [Leukocytosis] may indicate:
- Inflammation
- Infection
- Leukemic neoplasia
- Stress
- Tissue necrosis
- Trauma
Decreased WBC count [Leukopenia] may indicate:
- Autoimmune disease
- Bone marrow failure
- Bone marrow infiltration [e.g., myelofibrosis]
- Congenital marrow aplasia
- Drug toxicity [e.g., chloramphenicol]
- Nutritional deficiency
- Severe infection
Nursing consideration for WBC count:
- A high total WBC count with a left shift means that the bone marrow will release an increased amount of neutrophils in response to inflammation or infection.
- A “shift to the right” which is usually seen in liver disease, megaloblastic and pernicious anemia, and Down syndrome, indicates that cells have more than the usual number of nuclear segments.
- A “shift to the left” indicates an increased number of immature neutrophils is found in the blood.
- A low total WBC count with a left shift means a recovery from bone marrow depression or an infection of such intensity that the demand for neutrophils in the tissue is greater than the capacity of the bone marrow to release them into the circulation.
Serum Electrolytes Normal Lab Values
Electrolytes are minerals that are involved in some of the important functions in our body. Serum electrolytes are routinely ordered for a patient admitted to a hospital as a screening test for electrolyte and acid-base imbalances. Here we discuss the normal lab values of the commonly ordered serum tests: potassium, serum sodium, serum chloride, and serum bicarbonate. Serum electrolytes may be ordered as a “Chem 7” or as a “basic metabolic panel [BMP]”.
Serum Sodium [Na+] Normal Lab Values
Sodium is a major cation of extracellular fluid that maintains osmotic pressure and acid-base balance, and assists in the transmission of nerve impulses. Sodium is absorbed from the small intestine and excreted in the urine in amounts dependent on dietary intake.
Normal and critical values for serum Sodium [Na+]:
| Adult | 135—145 mmol/L | 135—145 mEq/L |
| Child | 136—145 mmol/L | 136—145 mEq/L |
| Infant | 134—150 mmol/L | 134—150 mEq/L |
| Newborn | 134—144 mmol/L | 134—144 mEq/L |
| Critical values | 160 mmol/L | 160 mEq/L |
Indications for Serum Sodium
- Determine whole-body stores of sodium, because the ion is predominantly extracellular
- Monitor the effectiveness of drug, especially diuretics, on serum sodium levels.
Increased sodium levels [Hypernatremia] may indicate:
- Cushing’s syndrome
- Diabetes insipidus
- Excessive dietary intake
- Excessive IV sodium administration
- Excessive sweating
- Extensive thermal burns
- Hyperaldosteronism
- Osmotic diuresis
Decreased sodium levels [Hyponatremia] may indicate:
- Ascites
- Addison’s disease
- Congestive heart failure
- Chronic renal insufficiency
- Deficient dietary intake
- Deficient sodium in IV fluids
- Diarrhea
- Diuretic administration
- Excessive oral water intake
- Excessive IV water intake
- Intraluminal bowel loss [e.g., ileus or mechanical obstruction]
- Osmotic dilution
- Peripheral edema
- Pleural effusion
- Syndrome of inappropriate ADH [SIADH] secretion
- Vomiting or nasogastric aspiration
Nursing consideration for Serum Sodium
- Drawing blood samples from an extremity in which an intravenous [IV] solution of sodium chloride is infusing increases the level, producing inaccurate results.
Serum Potassium [K+]
Potassium is the most abundant intracellular cation that serves important functions such as regulate acid-base equilibrium, control cellular water balance, and transmit electrical impulses in skeletal and cardiac muscles.
Normal and critical values for Potassium [K+]:
| Adult | 3.5—5.0 mmol/L | 3.5—5.0 mEq/L |
| Child | 3.4—4.7 mmol/L | 3.4—4.7 mEq/L |
| Infant | 4.1—5.3 mmol/L | 4.1—5.3 mEq/L |
| Newborn | 3.9—5.9 mmol/L | 3.9—5.9 mEq/L |
| Critical values [Adult] | 6.1 mmol/L | 6.1 mEq/L |
| Critical values [Newborn] | 8.0 mmol/L | 8.0 mEq/L |
Indications for Serum Potassium
- Evaluates cardiac function, renal function, gastrointestinal function, and the need for IV replacement therapy.
Increased potassium levels [Hyperkalemia] may indicate:
- Acidosis
- Acute or chronic renal failure
- Aldosterone-inhibiting diuretics
- Crush injuries to tissues
- Dehydration
- Excessive dietary intake
- Excessive IV intake
- Hemolysis
- Hemolyzed blood transfusion
- Hypoaldosteronism
- Infection
Decreased potassium levels [Hypokalemia] may indicate:
- Ascites
- Burns
- Cushing’s syndrome
- Cystic fibrosis
- Deficient dietary intake
- Deficient IV intake
- Diuretics
- Gastrointestinal disorders such as nausea and vomiting
- Glucose administration
- Hyperaldosteronism
- Insulin administration
- Licorice administration
- Renal artery stenosis
- Renal tubular acidosis
- Surgery
- Trauma
Nursing Considerations for Serum Potassium
- Note on the laboratory form if the client is receiving potassium supplementation.
- Clients with elevated white blood cell counts and platelet counts may have falsely elevated potassium levels.
Serum Chloride [Cl-]
Chloride is a hydrochloric acid salt that is the most abundant body anion in the extracellular fluid. Functions to counterbalance cations, such as sodium, and acts as a buffer during oxygen and carbon dioxide exchange in red blood cells [RBCs]. Aids in digestion and maintaining osmotic pressure and water balance.
Normal and critical values for Chloride [Cl-]:
| Adult | 95—105 mmol/L | 95—105 mEq/L |
| Child | 90—110 mmol/L | 90—110 mEq/L |
| Newborn | 96—106 mmol/L | 96—106 mEq/L |
| Premature infant | 95—110 mmol/L | 95—110 mEq/L |
| Critical values | 115 mmol/L | 115 mEq/L |
Increased chloride levels [Hyperchloremia] may indicate:
- Anemia
- Cushing’s syndrome
- Dehydration
- Eclampsia
- Excessive infusion of normal saline
- Hyperparathyroidism
- Hyperventilation
- Kidney dysfunction
- Metabolic acidosis
- Multiple myelomas
- Renal tubular acidosis
- Respiratory alkalosis
Decreased chloride levels [Hypochloremia] may indicate:
- Addison’s disease
- Aldosteronism
- Burns
- Chronic gastric suction
- Chronic respiratory acidosis
- Congestive heart failure
- Diuretic therapy
- Hypokalemia
- Metabolic alkalosis
- Overhydration
- Respiratory alkalosis
- Salt-losing nephritis
- Syndrome of inappropriate antidiuretic hormone [SIADH]
- Vomiting
Nursing Considerations for Serum Chloride
- Any condition accompanied by prolonged vomiting, diarrhea, or both will alter chloride levels.
Magnesium [Mg]
Magnesium is used as an index to determine metabolic activity and renal function. Magnesium is needed in the blood-clotting mechanisms, regulates neuromuscular activity, acts as a cofactor that modifies the activity of many enzymes, and has an effect on the metabolism of calcium.
Normal and critical values for Magnesium [Mg]:
| Adult | 0.7—1.05 mmol/L | 1.3—2.1 mEq/L |
| Child | 0.7—0.85 mmol/L | 1.4—1.7 mEq/L |
| Newborn | 0.7—1.0 mmol/L | 1.4—2.0 mEq/L |
| Critical values | 1.5 mmol/L | 3.0 mEq/L |
Increased magnesium levels [Hypermagnesemia] may indicate:
- Addison’s disease
- Hypothyroidism
- Ingestion of magnesium-containing antacids or salt
- Renal insufficiency
- Uncontrolled diabetes
Decreased magnesium levels [Hypomagnesemia] may indicate:
- Alcoholism
- Chronic renal disease
- Diabetic acidosis
- Hypoparathyroidism
- Malabsorption
- Malnutrition
Nursing Considerations
- Prolonged use of magnesium products causes increased serum levels.
- Long-term parenteral nutrition therapy or excessive loss of body fluids may decrease serum levels.
Serum Osmolality
Serum osmolality is a measure of the solute concentration of the blood. Particles include sodium ions, glucose, and urea. Serum osmolality is usually estimated by doubling the serum sodium because sodium is a major determinant of serum osmolality.
Normal and critical values for Serum Osmolality:
| Adult | 285—295 mmol/kg | 285—295 mOsm/kg H2O |
| Child | 275—290 mmol/kg | 275—290 mOsm/kg H2O |
| Critical values | 320 mmol/kg | 320 mOsm/kg H20 |
Serum Bicarbonate [HCO3-]
Part of the bicarbonate-carbonic acid buffering system and mainly responsible for regulating the pH of body fluids.
Normal and critical values for Serum Bicarbonate [HCO3-]:
| Adult | 23—30 mmol/L | 23—30 mEq/L |
| Child | 20—28 mmol/L | 20—28 mEq/L |
| Infant | 20—28 mmol/L | 20—28 mEq/L |
| Newborn | 13—22 mmol/L | 13—22 mEq/L |
| Critical values | 40 mmol/L | 40 mEq/L |
Nursing consideration for Serum Bicarbonate
- Ingestion of acidic or alkaline solutions may cause increased or decreased results, respectively.
Phosphorus [P]
Phosphorus [Phosphate] is important in bone formation, energy storage and release, urinary acid-base buffering, and carbohydrate metabolism. Phosphorus is absorbed from food and is excreted by the kidneys. High concentrations of phosphorus are stored in bone and skeletal muscle.
Normal and critical values for Phosphorus [P]:
| Adult | 0.97—1.45 mmol/L | 3.0—4.5 mg/dL |
| Child | 1.45—2.1 mmol/L | 4.45—6.5 mg/dL |
| Newborn | 1.4—3.0 mmol/L | 4.3—9.3 mg/dL |
| Critical values | 12 mg/dL | |
| Critical values [Newborn] | >256 µmol/L | >15 mg/dL |
| Direct bilirubin [conjugated] | 1.7—5.1 μmol/L | 0.1—0.3 mg/dL |
| Indirect bilirubin [unconjugated] | 3.4—12.0 μmol/L | 0.2—0.8 mg/dL |
Increased conjugated [direct] bilirubin levels may indicate:
- Cholestasis from drugs
- Dubin-Johnson syndrome
- Extensive liver metastasis
- Extrahepatic duct obstruction [gallstone, inflammation, scarring, surgical trauma, or tumor]
- Gallstones
- Rotor’s syndrome
Increased unconjugated [indirect] bilirubin levels may indicate:
- Cirrhosis
- Crigler-Najjar syndrome
- Erythroblastosis fetalis
- Gilbert’s syndrome
- Hemolytic anemia
- Hemolytic jaundice
- Hepatitis
- Large-volume blood transfusion
- Neonatal hyperbilirubinemia
- Resolution of a large hematoma
- Pernicious anemia
- Sepsis
- Sickle cell anemia
- Transfusion reaction
Nursing Considerations
- Instruct the client to eat a diet low in yellow foods, avoiding foods such as carrots, yams, yellow beans, and pumpkin, for 3 to 4 days before the blood is drawn.
- Instruct the client to fast for 4 hours before the blood is drawn.
- Note that results will be elevated with the ingestion of alcohol or the administration of morphine sulfate, theophylline, ascorbic acid [vitamin C], or acetylsalicylic acid [Aspirin].
- Note that results are invalidated if the client has received a radioactive scan within 24 hours before the test.
Albumin
Albumin is the main plasma protein of blood that maintains oncotic pressure and transports bilirubin, fatty acids, medications, hormones, and other substances that are insoluble in water. Albumin is increased in conditions such as dehydration, diarrhea, and metastatic carcinoma; decreased in conditions such as acute infection, ascites, and alcoholism. Presence of detectable albumin, or protein, in the urine is indicative of abnormal renal function.
Normal lab values for Albumin:
| Adult | 35—50 g/L | 3.5—5.0 g/dL |
| Child | 40—59 g/L | 4.0—5.9 g/dL |
| Infant | 44—54 g/L | 4.4—5.4 g/dL |
| Newborn | 35—54 g/L | 3.5—5.4 g/dL |
| Premature infant | 30—42 g/L | 3.0—4.2 g/dL |
Increased albumin levels [Hyperalbuminemia] may indicate:
- Dehydration
- Severe diarrhea
- Severe vomiting
Decreased albumin levels [Hypoalbuminemia] may indicate:
- Acute liver failure
- Cirrhosis
- Familial idiopathic dysproteinemia
- Inflammatory disease
- Increased capillary permeability
- Malnutrition
- Pregnancy
- Protein-losing enteropathies
- Protein-losing nephropathies
- Severe burns
- Severe malnutrition
- Ulcerative colitis
Nursing Considerations
- Fasting is not required.
Ammonia
Ammonia is a by-product of protein catabolism; most of it is created by bacteria acting on proteins present in the gut. Ammonia is metabolized by the liver and excreted by the kidneys as urea. Elevated levels resulting from hepatic dysfunction may lead to encephalopathy. Venous ammonia levels are not a reliable indicator of hepatic coma.
Normal values for Ammonia:
| Adult | 7—57 µmol/L | 10—80 µg/dL |
| Child | 29—57 µmol/L | 40—80 µg/dL |
| Newborn | 64—107 µmol/L | 90—150 µg/dL |
Nursing Considerations
- Instruct the client to fast, except for water, and to refrain from smoking for 8 to 10 hours before the test; smoking increases ammonia levels.
- Place the specimen on ice and transport to the laboratory immediately.
Amylase
Amylase is an enzyme, produced by the pancreas and salivary glands, aids in the digestion of complex carbohydrates and is excreted by the kidneys. In acute pancreatitis, the amylase level may exceed five times the normal value; the level starts rising 6 hours after the onset of pain, peaks at about 24 hours, and returns to normal in 2 to 3 days after the onset of pain. In chronic pancreatitis, the rise in serum amylase usually does not normally exceed three times the normal value.
Normal values for amylase:
| Adult | 30–220 units/L or 500 nkat/L | 60—120 Somogyi units/dL |
| Newborn | 3—32.5 units/L or 50—542 nkat/L | 6—65 Somogyi units/dL |
Increased amylase levels may indicate:
- Acute pancreatitis
- Acute cholecystitis
- Diabetic ketoacidosis
- Duodenal obstruction
- Ectopic pregnancy
- Necrotic bowel
- Parotiditis
- Penetrating peptic ulcer
- Perforated peptic ulcer
- Perforated bowel
- Pulmonary infarction
Decreased amylase levels may indicate:
- Chronic pancreatitis
- Cystic fibrosis
- Liver disease
- Preeclampsia
Nursing Considerations
- On the laboratory form, list the medications that the client has taken during the previous 24 hours before the test.
- Note that many medications may cause false-positive or false-negative results.
- Results are invalidated if the specimen was obtained less than 72 hours after cholecystography with radiopaque dyes.
Lipase
Lipase is a pancreatic enzyme converts fats and triglycerides into fatty acids and glycerol. Elevated lipase levels occur in pancreatic disorders; elevations may not occur until 24 to 36 hours after the onset of illness and may remain elevated for up to 14 days.
Normal values for Lipase:
| 0—160 units/L |
Increased lipase levels may indicate:
- Acute cholecystitis
- Acute pancreatitis
- Bowel obstruction or infarction
- Cholangitis
- Chronic relapsing pancreatitis
- Extrahepatic duct obstruction
- Pancreatic cancer
- Pancreatic pseudocyst
- Peptic ulcer disease
- Renal failure
- Salivary gland inflammation or tumor
Decreased lipase levels may indicate:
- Chronic conditions such as cystic fibrosis
Nursing Consideration
- Endoscopic retrograde cholangiopancreatography [ERCP] may increase lipase activity.
Serum Protein
Serum protein reflects the total amount of albumin and globulins in the plasma. Protein regulates osmotic pressure and is necessary for the formation of many hormones, enzymes, and antibodies; it is a major source of building material for blood, skin, hair, nails, and internal organs. Increased in conditions such as Addison’s disease, autoimmune collagen disorders, chronic infection, and Crohn’s disease. Decreased in conditions such as burns, cirrhosis, edema, and severe hepatic disease.
Normal values for Total Protein [Serum]:
| Adult | 54—83 g/L | 5.4—8.3 g/dL |
| Child | 62—80 g/L | 6.2—8.0 g/dL |
| Infant | 60—67 g/L | 6.0—6.7 g/dL |
| Newborn | 46—74 g/L | 4.6—7.4 g/dL |
| Premature infant | 42—76 g/L | 4.2—7.6 g/dL |
Increased protein levels may indicate:
- Amyloidosis
- Dehydration
- Hepatitis B
- Hepatitis C
- Human immunodeficiency virus
- Multiple myeloma
Decreased protein levels may indicate:
- Agammaglobulinemia
- Bleeding
- Celiac disease
- Extensive burns
- Inflammatory bowel disease
- Kidney disorder
- Liver disease
- Severe malnutrition
Glucose Studies Normal Lab Values
Understanding the normal laboratory values of blood glucose is an essential key in managing diabetes mellitus. Included in this section are the lab values and nursing considerations for glycosylated hemoglobin, fasting blood sugar, glucose tolerance test, and diabetes mellitus antibody panel.
Fasting Blood Glucose
Fasting blood glucose or fasting blood sugar [FBS] levels are used to help diagnose diabetes mellitus and hypoglycemia. Glucose is a monosaccharide found in fruits and is formed from the digestion of carbohydrates and the conversion of glycogen by the liver. Glucose is the main source of cellular energy for the body and is essential for brain and erythrocyte function.
Normal values for Glucose Studies:
| Glucose [Random, Casual] | 33 nmol/L | >25 ng/mL | |||
| Digoxin [Lanoxin] | Antiarrhythmics | 1—2.6 nmol/L | 0.8—2 ng/mL | >3 nmol/L | >2.4 ng/mL |
| Disopyramide [Norpace] | Antiarrhythmics | 6—15 µmol/L | 2—5 µg/mL | >15 µmol/L | >5 µg/mL |
| Ethosuximide [Zarontin] | Anticonvulsants | 283—708 μmol/L | 40—100 µg/mL | >700 μmol/L | >100 µg/mL |
| Gentamicin [Garamycin] | Aminoglycosides | 10—21 µmol/L | 5—10 µg/mL | >25 µmol/L | >12 µg/mL |
| Imipramine [Tofranil] | Antidepressants | 535—1170 nmol/L | 150—300 ng/mL | >1780 nmol/L | >500 ng/mL |
| Kanamycin [Kantrex] | Aminoglycosides | 41—52 µmol/L | 20—25 µg/mL | >70 µmol/L | >35 µg/mL |
| Lidocaine [Xylocaine HCL] | Anesthetic | 6.4—21 µmol/L | 1.5—5 µg/mL | >20 µmol/L | >5 µg/mL |
| Lithium [Eskalith] | Antimanic | 0.5—1.2 mmol/L | 0.8—1.2 mEq/L | >2 mmol/L | >2 mEq/L |
| Magnesium Sulfate | Anticonvulsants | 1.7—3 mmol/L | 4—7 mg/dL | >3 mmol/L | >7 mg/dL |
| Methotrexate [Trexall] | Antimetabolites | >0.01 µmol | >0.01 µmol | >10 µmol/24 hours | >10 µmol/24 hours |
| Nortriptyline [Aventyl HCl] | Antidepressants | 190—570 nmol/L | 50—150 ng/mL | >1900 nmol/L | >500 ng/mL |
| Phenobarbital [Luminal] | Anticonvulsant | 44—133 µmol/L | 10—30 µg/mL | >170 µmol/L | >40 µg/mL |
| Phenytoin [Dilantin] | Antiarrhythmic | 40—79 µmol/L | 10—20 µg/mL | >120 µmol/L | >30 µg/mL |
| Primidone [Mysoline] | Anticonvulsants | 23—55 µmol/L | 5—12 µg/mL | >69 µmol/L | >15 µg/mL |
| Procainamide [Pronestyl] | Antiarrhythmics | 17—43 µmol/L | 4—10 µg/mL | >68 µmol/L | >16 µg/mL |
| Propranolol [Inderal] | Antiarrhythmics | 193—386 nmol/L | 50—100 ng/mL | >580 nmol/L | >150 ng/mL |
| Quinidine [Cardioquin] | Antiarrhythmics | 6—15 µmol/L | 2—5 µg/mL | >31 µmol/L | >10 µg/mL |
| Salicylate [Aspirin] | Analgesic | 0.72—18 mmol/L | 100—2500 µg/mL | >2 mmol/L | >300 µg/mL |
| Sirolimus [Rapamune] | Immunosuppressant | 3—22 nmol/L | 3—20 ng/mL | >22 nmol/L | >20 ng/mL |
| Tacrolimus [Astagraf XL] | Calcineurin inhibitors | 6—19 nmol/L | 5—15 ng/mL | >25 nmol/L | >20 ng/mL |
| Theophylline [Theo-24] | Methylxanthines | 56—111 µmol/L | 10—20 µg/mL | >111 µmol/L | >20 µg/mL |
| Tobramycin | Aminoglycosides | 11—21 µmol/L | 5—10 µg/mL | >26 µmol/L | >12 µg/mL |
| Valproic acid [Depakene] | Anticonvulsants | 350 —700 µmol/L | 50—100 µg/mL | >700 µmol/L | >100 µg/mL |
| Vancomycin [Firvanq] | Glycopeptide antibiotics | 14—28 µmol/L | 20—40 µg/mL | >28 µmol/L | >40 µg/mL |
How to Obtain a Blood Sample
A phlebotomist or a nurse with training and certification in collecting a blood sample are allowed to perform venipuncture for the purpose of blood specimen collection. These are the steps to follow in obtaining a blood sample:
- Identify the client. Accurately identify the client by asking his or her name and birthdate; Explain the reason for the test and procedure to the client.
- Proper position. Blood samples should be drawn in a sitting position and the client should remain in that position for at least 5 minutes before the blood collection.
- Confirm the request. Check the laboratory form for the ordered test, client information, and additional requirements [fasting, dietary restrictions, medications].
- Provide comfort. Make sure the client remove any tight clothing that might constrict the upper arm. The arm is placed in a downward position supported on the armrest.
- Ensure proper hand hygiene. Perform hand washing before putting on non-latex gloves.
- Identify the vein. Examine the client’s arm to select the most easily accessible vein for venipuncture then place the tourniquet 3 to 4 inches above the chosen site. Do not place the tourniquet tightly or leave on more than 2 minutes.
- Prepare the site. When a vein is chosen, cleanse the area using alcohol in a circular motion beginning at the site and working toward.
- Draw the sample. Ask the client to make a fist. Grasp the client’s arm firmly using your thumb to draw the skin taut and anchor the vein from rolling. Gently insert the needle at a 15 to 30º angle through the skin and into the lumen of the vein.
- Fill the tube. Obtain the needed amount of blood sample, then release and remove the tourniquet.
- Remove the needle. In a swift backward motion, remove the needle from the client’s arm. and apply a folded gauze over the venipuncture site for 1 to 2 minutes.
- Label the tube. Label the tube with the client’s name, date of birth, hospital number, date and time of the collection.
- Transport specimen. Deliver the specimen to the laboratory for immediate processing and analysis.
References and Sources
Suggested reading and additional resources for this Normal Laboratory Values guide:
- Corbett, J. V., & Banks, A. [2018]. Laboratory Tests and Diagnostic Procedures with Nursing Diagnoses with Nursing Diagnoses. Pearson Education. [Link]
- Kratz, A., & Lewandrowski, K. B. [1998]. Normal reference laboratory values. New England Journal of Medicine, 339[15], 1063-1072. [Link]
- Kratz, A., Ferraro, M., Sluss, P. M., & Lewandrowski, K. B. [2004]. Laboratory reference values. New England Journal of Medicine, 351, 1548-1564. [Link]