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| Helpful Ideas |
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Lab Test Monitoring: Bringing Nurses into the Equation
| Problem: Nursing staff often lack an adequate understanding of the importance of laboratory monitoring and the implications of abnormal lab values.
Solution: Our pharmacy has created a reference chart and related in-service program to help nurses be more attuned to the clinical significance of certain abnormal lab values. |
Clinical laboratory tests are a key component of diagnosis, prognostic assessment, and evaluation of therapeutic outcomes. As part of our daily practice activities, consultant pharmacists have extensive exposure to laboratory tests. We examine patients’ current lab values, make recommendations for optimal drug therapy based on those values, and suggest additional lab tests to aid in monitoring both therapeutic outcomes and overall health status.
It is important to keep in mind, however, that all members of the interdisciplinary team may not be as attuned to lab values and their clinical significance. In particular, nursing staff, who often are responsible for communicating lab data to the prescriber, may be unfamiliar with the rationale for doing a particular test, the implications of abnormal lab values, and the possible nursing interventions that may be necessary to address those abnormal values. If they don’t fully understand the importance of abnormal test values, nursing staff may fail to alert the prescriber in a timely manner, possibly leading to further deterioration of the patient’s condition.
In an effort to increase nursing staff awareness of the importance of laboratory data, our pharmacy developed an in-service tool explaining the rationale behind frequently ordered lab tests. Although nursing staff may already be familiar with the pharmacy’s current laboratory policies, this program goes a step further by teaching nurses why the test is done and the implications of abnormal values. Also included is information regarding how a patient’s medication regimen may be contributing to the abnormal value, as well as suggestions for ways nurses may intervene to assist in detecting clinical signs and symptoms associated with abnormal laboratory values.
After questioning nursing staff at the long-term care facilities our pharmacy serves, we found they had a particular interest in learning when to withhold medications because of an abnormal lab value, as well as information regarding clinical signs and symptoms to expect in their patients with abnormal test results. We divided the lab tests into two broad categories: those for assessing metabolic function and those for medication monitoring.
Assessing Metabolic Function
Laboratory tests for assessing metabolic function include electrolyte tests, liver function tests, albumin levels, and complete blood cell counts. Electrolyte values are particularly important for the nursing staff to monitor. Our lab test form, which is designed to be kept with medication administration records, describes signs and symptoms associated with high or low values, as well as possible nursing interventions in the event of an abnormal result. Figure 1 shows how our monitoring form presents information signs and symptoms associated with abnormal sodium and potassium values, and possible nursing interventions.| Figure 1. Lab Test Monitoring Form: Selected Electrolyte Entries | ||||
| Test | Reason | Symptoms When Elevated | Symptoms When Low | Nursing Interventions |
| Electrolytes | Monitor blood chemistries | |||
| Sodium (NA+) | Intense thirst, lethargy, diminished reflexes, muscle spasms, seizures, coma, death | Weakness, confusion, stupor, hypotension, seizures, edema, weight gain | Elevated: Hold medications high in sodium content Low: Potential medication cause may be carbamazepine | |
| Potassium (K+) | Irritability, nausea, diarrhea, abdominal cramps, weakness, EKG changes, ventricular fibrillation | Malaise, confusion, thirst, polyuria, muscle weakness, diminished reflexes, loss of muscle tone, arrhythmias, hypotension, respiratory dysfunction, EKG changes | Elevated: Hold KCl, K+ sparing diuretics Low: Potential medication cause may be diuretics | |
| EKG = electrocardiogram; N/V = nausea/vomiting. | ||||
To reinforce the quick-reference information presented in the form, our pharmacists conduct an in-service program to educate nurses about the critical importance of electrolyte balances to maintenance of normal body functions.
For example, we teach nurses that sodium regulates osmotic pressure and water balance between intracellular and extracellular fluids, in addition to playing a role in nerve and muscle cells for regulating membrane potentials. We teach them about potential clinical manifestations of electrolyte imbalances, including water imbalances and neuromuscular signs and symptoms. The form itself reminds nurses that potassium is essential to maintaining proper electrical conduction in cardiac and skeletal muscles. In addition, the form lists common clinical manifestations such as neuromuscular symptoms and electrocardiographic changes. Symptoms such as confusion, dizziness, and stupor are highlighted as potential presenting symptoms in patients with an electrolyte imbalance. Potential interventions, such as withholding of medications that may potentiate the imbalance, are discussed, and a chart of medications with high sodium content is provided.
Medication Monitoring
The sections of our form addressing lab tests for medication monitoring focus on quot;narrow therapeutic indexquot; drugs such as theophylline, phenytoin, carbamazepine, phenobarbital, warfarin, digoxin, and lithium. Signs and symptoms of elevated levels, as well as symptoms associated with subtherapeutic serum concentrations, are presented in a chart for easy reference. Figure 2 shows chart entries for three narrow therapeutic index drugs, with information on symptoms of abnormal laboratory values associated with each drug and potential nursing interventions to improve patient outcomes.Several laboratory tests used for blood monitoring are also included in our form (see Figure 3).
| Figure 2. Selected NTI Drug Entries | ||||
| Test | Reason | Symptoms When Elevated | Symptoms When Low | Nursing Interventions |
| Drug Levels | Monitor efficacy and toxicity | |||
| Carbamazepine (Tegretol) | N/V, lethargy, HA, ataxia, drowsiness, dizziness | Seizure activity | ||
| Digoxin (Lanoxin) | Anorexia, N/V, weakness, vision disturbances (colors or halos), depression, and confusion | CHF may worsen, or signs and symptoms of AFIB may appear (clinically subtherapeutic) | Elevated: K+ level affects digoxin distribution; hold KCl and K+ sparing diuretics | |
| Lithium | Fine tremors, gastrointestinal upset, sedation/lethargy, muscle weakness, agitation, delirium, seizures | Fine tremors, gastrointestinal upset, sedation/lethargy, muscle weakness, agitation, delirium, seizures | Elevated: Lithium behaves like Na+ in the kidney; hold medications with high Na+ content | |
| AFIB = atrial fibrillation; CHF = congestive heart failure; HA = headache; N/V = nausea/vomiting. | ||||
Because we have found that nursing staff are often unfamiliar with the international normalized ratio (INR), our form also emphasizes the importance of monitoring the INR value, rather than only the prothrombin time. Nurses are responsible for assessing the clinical status of their patients and relaying laboratory information to other members of the health care team; therefore, it is crucial that they have a good understanding of laboratory data.
| Figure 3. Blood Cell Count Entries Lab Test | ||||
| Test | Reason | Symptoms When Elevated | Symptoms When Low | Nursing Interventions |
| Complete blood cell count | Monitor blood cell counts | |||
| Red blood cells (RBCs) | Most often used to evaluate anemias | Hypoxia | Fatigue, pallor, dyspnea, tachycardia, palpitations | |
| Hemoglobin (Hb) | Measure of oxygen transport | - | Fatigue, poor appetite, coldness, depression | |
| Hematocrit (Hct) | Measures percent of RBCs in plasma | - | Fatigue, poor appetite, coldness, depression | |
| White blood cells (WBCs) | Infection, fever, weakness, aches, leukemia | Leukopenia, neutropenia, more susceptible to infection | ||
| Platelets | Responsible for clot formation | Thrombocythemia | Thrombocytopenia: easy bruising, hemorrhage, bleeding gums | |
| Prothrombin time/ international normalized ratio* | Standard lab value used to monitor warfarin therapy | Increased risk of bleeding | Thromboembolic event may occur (DVT, PE) | Elevated: Check for signs and symptoms of bleeding; may need to hold warfarin dose Low: Warfarin dosage may need to be increased |
| *The standard of practice is to use the INR to monitor warfarin therapy. DVT = deep venous thrombosis; PE = pulmonary embolism. | ||||
Together, the quick-reference chart and in-service program have proved to be effective tools for helping nurses understand the clinical context of lab tests and provide optimal care to patients with abnormal lab values.
Alexis Sappenfield, PharmD candidate
Caren McHenry Martin, PharmD
Campbell University School of Pharmacy
Buies Creek, North Carolina
Neil Medical Group
Winston-Salem, North Carolina
American Society of Consultant Pharmacists.