From the Guidelines
For a patient undergoing angiography, I recommend ordering the following laboratory tests: complete blood count (CBC), comprehensive metabolic panel (CMP), coagulation studies (PT/INR, PTT), and kidney function tests (BUN, creatinine, eGFR). The CBC helps assess for anemia or infection, while the CMP provides information about electrolyte balance and liver function. Coagulation studies are crucial to evaluate bleeding risk during the procedure, as noted in the 2014 ACC/AHA/AATS/PCNA/SCAI/STS focused update of the guideline for the diagnosis and management of patients with stable ischemic heart disease 1. Kidney function tests are particularly important because contrast media used during angiography can cause contrast-induced nephropathy in patients with pre-existing renal impairment, a concern highlighted in the same guideline 1. For patients on anticoagulants, medication-specific tests may be needed (e.g., anti-Xa levels for patients on heparin). Additionally, type and screen should be considered if there's potential for significant blood loss. These tests should ideally be performed within 30 days of the procedure, though kidney function tests are often repeated 24-48 hours before the procedure to ensure the most current assessment of renal status. Patients with diabetes who take metformin may need to temporarily discontinue this medication before and after the procedure to reduce the risk of lactic acidosis when contrast is administered. It's also important to consider the patient's overall clinical context, including symptoms and medical history, as outlined in the clinical practice guideline for the use of antimicrobial agents in neutropenic patients with cancer 1, although this guideline is not directly applicable to angiography, it emphasizes the importance of considering the patient's overall health status when ordering laboratory tests. The most recent and highest quality study, the 2014 ACC/AHA/AATS/PCNA/SCAI/STS focused update 1, provides the basis for these recommendations, prioritizing the patient's morbidity, mortality, and quality of life as the primary outcomes. Key points to consider include:
- The importance of kidney function tests due to the risk of contrast-induced nephropathy
- The need for coagulation studies to assess bleeding risk
- The consideration of medication-specific tests for patients on anticoagulants
- The potential need to temporarily discontinue metformin in diabetic patients
- The importance of considering the patient's overall clinical context when ordering laboratory tests.
From the Research
Laboratory Tests for Angiography
To prepare a patient for angiography, several laboratory tests are typically ordered to assess their overall health and identify potential risks. The following tests are commonly recommended:
- Complete Blood Count (CBC) 2: This test measures various components of the blood, including red and white blood cell counts, hemoglobin, and platelet count.
- Blood Urea Nitrogen (BUN) and Serum Creatinine 3, 4: These tests evaluate kidney function and can help identify potential kidney problems that may affect the patient's ability to undergo angiography.
- Electrolyte panel 4: This test measures the levels of essential electrolytes, such as potassium, sodium, and chloride, which can help identify potential imbalances that may affect the patient's heart rhythm or other bodily functions.
Rationale for Laboratory Tests
The rationale for ordering these laboratory tests is to:
- Assess the patient's overall health and identify potential risks associated with angiography
- Evaluate kidney function and potential kidney problems that may affect the patient's ability to undergo angiography 3, 4
- Identify potential electrolyte imbalances that may affect the patient's heart rhythm or other bodily functions 4
- Inform the patient's plan of care and produce the best patient outcomes 2