Common Laboratory Tests - Basic Metabolic Panel

Common laboratory tests: Interpretation and Nursing Implications NURS 325 *Note: These values are consistent with the normal ranges in ATI. Normal laboratory value reference ranges vary slightly depending on the facility or textbook used. Basic Metabolic Panel Lab value Reference range* Interpretation and Nursing Implications Hyponatremia: Strict I/O, daily weights, monitor for GI symptoms (anorexia, nausea, vomiting, abdominal cramping) and CNS symptoms (lethargy, confusion, muscle twitching, seizures). Avoid giving large water supplements. Seizure precautions when hyponatremia is severe. Sodium 136-145 mEq/L Depending on cause, treatments include isotonic IV fluids, avoid diuretics, fluid restriction, hypertonic saline (severe cases). Hypernatremia: Strict I/O, daily weights, and monitor for changes in behavior such as restlessness, lethargy, and disorientation. Look for excessive thirst and elevated body temperature. Provide sufficient water intake. Depending on cause, treatments include fluid replacement (oral or IV). Hypokalemia can be life-threatening. For patients taking digoxin, assess for hypokalemia, which potentiates the action of digitalis. Patients with hypokalemia are at risk of cardiac arrhythmias. Monitor patients for muscle cramps and weakness, paresthesias, fatigue, anorexia, decreased bowel motility, and an irregular heartbeat. To prevent hypokalemia, educate patients about abuse of laxatives and diuretics. If giving IV potassium supplementation, administer per facility policy (e.g. no more than 10 meq/hr) and monitor IV site closely. Potassium 3.5-5.0 mEq/L If giving oral supplementation, give with food, do not crush extended release caps/tabs, and dilute liquid potassium as directed. Potassium is renally cleared, so check to make sure that patient has adequate urine output and creatinine clearance (at least 30 mL/min) before repleting. Hyperkalemia can be life-threatening. Monitor patients for arrhythmias, irritability, paresthesias, and anxiety, as well as GI symptoms such as nausea and intestinal colic. Avoid giving patients with renal insufficiency potassium-sparing diuretics, potassium supplements, or salt substitutes. Patients on ACE inhibitors should avoid potassium supplements. Treatment is usually needed when the patient is symptomatic. Treatments may include Sodium polystyrene sulfonate (Kaexylate)—removes potassium via GI tract, IV insulin (temporarily shifts insulin into the cell), albuterol (temporarily shifts insulin into the cell), IV calcium chloride or gluconate (protects the myocardium from the harmful effects of hyperkalemia). *Note: This is not the same as carbon dioxide on the ABG! CO2 (Total CO?) 23-29 mEq/L or mmol/L Total CO2 content includes the serum bicarbonate as well as available forms of carbon dioxide (i.e., dissolved CO2 and carbonic acid). Serum bicarbonate comprises about 95% of the total CO2 so this test on a chemistry panel can be used to evaluate acid-base balance High levels indicate metabolic alkalosis Low levels indicate metabolic acidosis Measures the concentration of urea in the blood. Urea concentration is regulated by renal excretion 10-20 mg/ dL BUN (Blood Urea Nitrogen) Increased levels may be due to dehydration and/or renal impairment. A less common cause is GI bleeding due to digestion of protein in the blood. Nursing implications: Monitor I/O, weights, and avoid nephrotoxins (esp. medications). Decreased levels may be due to liver cirrhosis, malnutrition, or fluid volume excess. Low levels are not usually a cause for concern. Female: Creatinine is end product of muscle and protein metabolism and is released as a constant rate. It’s 0.5-1.1 mg/ more reliable than BUN when assessing renal function. dL Creatinine Male: Increased levels indicate renal impairment. Avoid nephrotoxins, monitor I/O and daily weights Decreased levels are usually not significant and only indicative of low muscle mass. Low serum 0.6–1.2 mg/ creatinine does not indicate renal impairment. dL eGFR is used to screen for and detect early renal impairment. It’s a calculation based on the serum creatinine along with other variables such as age, sex, and race. African Americans tend to have a higher GFR than Caucasians due to differences in muscle mass composition but similar serum creatinine levels. Creatinine is cleared solely by the kidneys and is therefore directly proportional to the glomerular filtration rate Estimated Glomerular Filtration Rate (eGFR) > 60 mL/min (eGFR) Low levels: Less than 60 indicates some renal impairment Less than 30 indicates severe renal impairment Less than 15 indicated probable need for renal replacement therapy (i.e. dialysis) Avoid nephrotoxins, monitor I/O and daily weights High levels: Some medications can cause hyperglycemia (corticosteroids, diuretics, total parenteral nutrition), even if the patient does not have diabetes. Check PRN insulin orders to see if additional insulin needs to be given. In general, notify provider if greater than 300 mg/dL. Low levels: Follow provider orders/protocols for treating hypoglycemia. Recheck blood glucose 15 minutes after treatment and re-treat if necessary. Glucose *see note Normal levels Fasting plasma glucose: 70-105 mg/dL Postprandial plasma glucose at 2 hours: < 140 mg/dL Random plasma glucose: < 140 mg/dL Hypoglycemia: < 70 mg/dL Reflects the total level of all forms of plasma calcium (protein bound and free/ionized). Serum albumin affects interpretation. When serum albumin is low, serum calcium will be low (and vice versa). The formula below can be used to calculate the “corrected” calcium level. Corrected total calcium (mg/dL) = (measured total calcium mg/dL) + 0.8 (for every decrement in the serum albumin of 1 g/dL below the reference value [in many cases 4.1 g/dL]; subsequently, subtract 0.8 for every increment in the serum albumin of 1 g/dL above the reference value) Calcium 9.0-10.5 mg/dL Severe hypocalcemia: Take seizure precautions and assess the airway; and take safety precautions if confusion is present. Also, monitor for tetany, tingling sensations in the tips of the fingers, around the mouth, and in the feet. Spasms of the muscles of the extremities and face may occur. Monitor for hyperactive deep tendon reflexes as well. Also, be alert for ECG changes including a prolonged QT interval. Treatment includes oral calcium and vitamin D supplements and IV calcium gluconate. Hypercalcemia: Increase mobilization as appropriate and encourage sufficient oral intake. Take safety precautions if confusion is present and be alert for signs of digitalis toxicity. Also, monitor the patient’s cardiac rate and rhythm. Treatment includes fluids (3-4L/day) and if severe, isotonic saline, bisphosphonate medication, and calcitonin. Hypermagnesemia: Often associated with renal impairment Significant clinical manifestations: Neuromuscular impairment, Hypotension, Risk of coma, respiratory and cardiac arrest Treatment: Avoid magnesium-containing medications, IV/oral fluids OR dialysis, IV calcium gluconate Magnesium 1.3-2.1 mEq/L Hypomagnesemia: Often associated w/ low intake or GI/renal loss Significant clinical manifestations (similar to hypocalcemia): Risk of dysrhythmias and cardiac arrest; can precipitate digitalis toxicity; risk of seizures and stridor if very low Treatment: Oral supplementation, IV supplementation (give over 30-60 minutes, depending on dose); magnesium is renally cleared, so check to make sure that patient has adequate urine output and creatinine clearance (at least 30 mL/min) before repleting. Hyperphosphatemia: Common w/ renal impairment Often asymptomatic unless patient also has hypocalcemia due to phosphate/calcium binding Treatment: Restrict dairy products, administer binding agents such as sevelamer (Renagel), administer calcium carbonate, dialysis Phosphorus Hypophosphatemia: Often due to nutritional or absorption deficiencies or shifts from ECF to ICF; s 3.0-4.5 mg/ evere hypophosphatemia increases infection risk by inhibiting WBC function. dL Significant clinical manifestations: Mild to moderate: Asymptomatic; Severe: CNS depression, muscle weakness, respiratory and heart failure Treatment: IV repletion (usually given over 4-6 hours), oral repletion (mix powder or liquid with an adequate amount of fluid) Complete blood cell count Lab value Reference range* Interpretation and Nursing Implications Total number of leukocytes (all types) 5,000 – 10 ,000/µL White blood cells (WBC) Or 5.0-10.0 x 109/L Leukocytosis: Elevated WBC count (> 11.0/11,000) is seen in response to infection, stress, inflammatory disorders or abnormal production as in leukemia. An increased WBC count can be due to an individual cell component or a combination, depending on the cause. Clinical manifestations include malaise, chills, and fever (related to infection). Nursing implications: Assess for manifestations of infection (assess temperature, breath sounds, urine output, surgical sites, invasive lines/tubes). Leukopenia: Decreased WBC count is commonly seen when supply is depleted by infection or treatment (e.g. chemotherapy or radiation) or when a hematopoietic stem cell abnormality does not allow normal growth/maturation within the bone marrow, such as myelodysplastic syndrome or leukemia. Leukopenia is most often due to a lower number of neutrophils, referred to as neutropenia. Nursing implications: Infection prevention (handwashing, avoiding sick contacts, avoiding invasive procedures). Measurement of gas-carrying capacity of the red blood cell (RBC) Female: 12-16 g/dL Hemoglobin Male: 14-18 g/dL Anemia: Low hemoglobin. Clinical manifestations depend on whether the anemia is acute (e.g. GI bleeding) or chronic (iron deficiency anemia). Chronic anemia is usually asymptomatic if hemoglobin is greater than 10. Acute or chronic: Watch for orthostatic hypotension, dizziness, pallor, fatigue, activity intolerance. Increased hemoglobin is less common and can be found due to hemoconcentration of the blood or in smokers due to polycythemia. Measure of packed cell volume of RBCs expressed as a percentage of the total volume; Hematocrit Female: 37level is generally 3x hemoglobin 47% Hematocrit Male: 42-52% Increased hematocrit values are seen in severe fluid volume deficit Decreased hematocrit values are seen with acute, massive blood loss; hemolytic reaction after transfusion of incompatible blood; or with fluid overload Number of platelets available to maintain platelet clotting functions (major part of primary hemostasis when platelets aggregate to form a platelet plug); does not measure quality of platelet function High platelets (thrombocytosis) are often seen with inflammation, infection, and cancer. Risk of clot formation (thrombosis). Platelets Low platelets (thrombocytopenia) is usually related to disorders in which the bone marrow can’t 150,000 – produce enough platelets or the platelets are being consumed or destroyed faster than they can be 400,000/µL replaced (e.g. hemorrhage). Nursing implications: Avoid invasive procedures, monitor for bleeding. Risk of bleeding with invasive procedures when platelet count less than 50,000. Patients with platelet count of less than 50,000 will usually need a platelet transfusion prior to an invasive procedure. Risk of spontaneous bleeding when platelet count is less than 10,000 to 20,000. Patients are usually prescribed a platelet transfusion to prevent spontaneous hemorrhage. Coagulation studies PT is used to help detect and diagnose a bleeding disorder or excessive clotting disorder; the INR is calculated from a PT result and is used to monitor how well warfarin (Coumadin®) is working. These tests are always performed together and collected in the same blood tube. Prothombin time (PT) International Normalized Ratio (INR) 11-12.5 seconds 0.8-1.1 PT: Assesses of extrinsic coagulation by measurement of factors I, II, V, VII, & X INR: Warfarin is considered therapeutic if 2-3 (goal may be higher depending on reason for medication) A prolonged PT means that the blood is taking too long to form a clot and may be caused by conditions such as liver disease, vitamin K deficiency, or a coagulation factor deficiency (if not on anticoagulants). Nursing implications: Avoid invasive procedures, risk of bleeding. Therapeutic range for anticoagulant therapy is 1.5 to 2 times the normal control value. Critical Value greater than 20 seconds. Assessment of intrinsic coagulation by measurement of factors I, II, V, VIII, IX, X, XI, XII aPTT is used to evaluation unfractionated heparin therapy (by continuous infusion), goal is 1.5-2x control value (in seconds). Activated Partial 30-40 Thromoplastin Time ( seconds PTT/aPTT ) Patients on subcutaneous heparin do not have this test performed routinely because the halflife of heparin is short and the dose is so low that it will not significantly increase the aPTT. A prolonged aPTT means that clotting is taking longer to occur than normal and may be due to a variety of causes (if not receiving unfractionated heparin). This suggests that a coagulation factor deficiency or a specific or nonspecific antibody affecting the body's clotting ability. Coagulation factor deficiencies may be acquired or inherited. Critical Value greater than 70 seconds.