Can a patient pending a Hepatobiliary Iminodiacetic Acid (HIDA) scan, especially an elderly patient or one with a history of cardiovascular disease, take melatonin?

Melatonin Use Before HIDA Scan

Yes, a patient can safely take melatonin before a HIDA scan, as there are no documented interactions between melatonin and hepatobiliary imaging procedures, and melatonin does not interfere with gallbladder function or biliary excretion required for accurate scan interpretation.

Safety Profile Relevant to HIDA Scanning

• Melatonin has no known effects on hepatobiliary function, bile flow, or gallbladder contractility that would compromise HIDA scan accuracy 1
• The American Academy of Sleep Medicine reports no serious adverse reactions documented with melatonin use, with the most common side effects being headache (0.74%) and dizziness (0.74%), neither of which would affect scan quality 1
• The Society for Perioperative Assessment and Quality Improvement recommends continuing melatonin through the perioperative period, demonstrating its safety even in more invasive medical contexts than diagnostic imaging 1

Special Considerations for Elderly and Cardiovascular Patients

For elderly patients or those with cardiovascular disease, melatonin remains safe before HIDA scanning, though specific precautions apply:

• A prospective trial of 500 cardiac surgery patients receiving melatonin showed no cardiac complications, confirming cardiovascular safety even in high-risk populations 1
• The American Heart Association, American College of Cardiology, and Heart Failure Society of America do not list melatonin as contraindicated in cardiac disease 1
• However, exercise caution in patients taking warfarin, as melatonin may potentiate anticoagulant effects; monitor INR more frequently if both medications are used 1

Timing Recommendations

• If the patient takes melatonin regularly for sleep, continue the usual dose at the usual time (typically 1-2 hours before bedtime) 2
• For morning HIDA scans, the previous evening's melatonin dose will not interfere with the procedure, as melatonin has a short half-life and is cleared by morning 3
• No need to hold melatonin doses before the scan unless specifically instructed by the nuclear medicine department for unrelated reasons 1

Common Pitfalls to Avoid

• Do not confuse melatonin with medications that actually affect gallbladder function (such as opioids, which can cause sphincter of Oddi spasm and interfere with HIDA scans) 1
• Do not discontinue melatonin unnecessarily, as this may worsen sleep disturbances without providing any benefit to scan quality 1
• Ensure the patient follows standard HIDA scan fasting requirements (typically 4-6 hours), which is separate from any melatonin considerations 1