The nurse prepares to administer lithium, a mood stabilizing drug, to a patient. Which laboratory result should first be assessed?
A.
Serum creatinine
B.
Serum troponin I and T levels
C.
Fasting blood glucose level
D.
Serum lipid profile
The Correct Answer and Explanation is:
The correct answer is A. Serum creatinine.
Explanation:
Lithium is a mood-stabilizing drug commonly used to treat bipolar disorder, particularly in managing manic episodes. While effective, lithium has a narrow therapeutic index, meaning the difference between therapeutic and toxic levels is small. Therefore, it is crucial to monitor various lab values to ensure safe administration. Among these, serum creatinine is of particular importance because lithium is excreted primarily by the kidneys.
1. Importance of Renal Function: Lithium is eliminated from the body through the kidneys, making renal function a critical factor in its metabolism and clearance. Any impairment in kidney function can lead to lithium accumulation in the body, increasing the risk of toxicity. Serum creatinine is a key marker of renal function, reflecting the ability of the kidneys to filter waste products. Elevated serum creatinine levels may indicate impaired renal function, necessitating careful dosing or even avoidance of lithium therapy in such patients.
2. Lithium Toxicity: Signs of lithium toxicity include nausea, vomiting, diarrhea, tremors, confusion, and, in severe cases, seizures and coma. Monitoring kidney function through serum creatinine helps prevent toxicity, as the kidneys play a crucial role in excreting the drug. In patients with compromised renal function, the risk of lithium buildup and subsequent toxicity is greatly increased.
3. Other Lab Values:
- B. Serum troponin I and T levels: These are cardiac biomarkers used to assess heart muscle injury, typically in the context of myocardial infarction (heart attack). While important for cardiovascular issues, they are not directly relevant to lithium administration.
- C. Fasting blood glucose level: This is used to assess blood sugar control, particularly in patients with diabetes or at risk for it. Lithium does not typically affect glucose metabolism.
- D. Serum lipid profile: This measures cholesterol and triglycerides to assess cardiovascular risk, but it is not directly impacted by lithium.
By first assessing serum creatinine levels, the nurse ensures that the patient’s kidneys can safely excrete lithium, minimizing the risk of toxicity.