Final answer:
The nurse should check the patient's serum creatinine levels before administering captopril, as this will give an indication of the kidney's filtering capacity and help assess the risk of medication accumulation due to reduced renal function.
Step-by-step explanation:
Before administering captopril to a patient with stage 2 chronic kidney disease (CKD), it is important to check the patient's serum creatinine levels. Creatinine is a metabolite of creatine, found in muscle, and is used to estimate the glomerular filtration rate (GFR), which reflects the kidney's excretory function. Checking creatinine levels helps assess whether the kidney's ability to filter blood has been compromised, which is critical because medications like captopril are excreted via the kidneys and could accumulate to toxic levels if kidney function is impaired.
According to the clinical guidelines, individuals with a GFR <60 mL/min/1.73 m² for 3 months or more are considered to have CKD, and administering medication requires careful consideration of GFR to avoid adverse drug accumulations. Creatinine clearance can also indirectly indicate GFR and is used in clinical settings to adjust medication dosages accordingly to avoid potential toxicity.