Important: This article is for educational purposes only. Always follow your imaging facility's specific preparation instructions. DOD does not provide scan preparation guidance — facility protocols vary and must be followed.
Why Labs May Be Needed Before CCTA
CCTA uses iodinated IV contrast, which is filtered by the kidneys. If kidney function is impaired, the contrast may cause or worsen kidney injury (contrast-induced nephropathy). To assess kidney function before contrast administration, facilities often require a recent blood test.
eGFR / Creatinine
The estimated glomerular filtration rate (eGFR) and serum creatinine are blood tests that measure kidney function. Facilities use these values to determine whether IV contrast is safe for you.
Requirements vary by facility — some require labs within 30 days, others within 90 days. Your provider may request lab results as part of the CCTA order review. DOD can also provide a lab order for eGFR/creatinine if needed.
Contrast Allergy Screening
If you have a history of allergic reaction to IV contrast, iodine, or shellfish, the facility needs to know. Pre-medication protocols may be required before contrast administration. Your provider reviews allergy history as part of the CCTA order review.
Medication Review
Certain medications may need to be managed before contrast-enhanced CT. For example, metformin — a common diabetes medication — may need to be held before and after contrast in some patients with impaired kidney function.
Never stop or change medications without consulting your prescribing provider. Your DOD provider reviews your medication list during the CCTA order review, but medication management decisions are made by your treating providers.
Other CCTA Preparation Considerations
Heart rate control: CCTA often requires a low, steady heart rate. Facility protocols may include beta-blockers before the scan.
Fasting: Facilities may require fasting (no food or drink) for several hours before CCTA.
Hydration: Drinking water before and after contrast helps protect kidney function.
Facility-specific protocols: Always follow your imaging facility's exact preparation instructions.
Emergency Warning: If you have chest pain, shortness of breath, fainting, or symptoms concerning for a heart attack or emergency, call 911 or go to the emergency room. CCTA is for non-emergency, preventive, or risk-stratification purposes only.
Need a Lab Order or CCTA Order?
DOD provides $40 virtual provider reviews for both lab orders (including eGFR/creatinine) and CCTA order requests. If medically appropriate, orders may be issued that you can take to the lab or imaging facility of your choice.