Potential hazard of methylene blue.

Area of Science:

• Biochemistry
• Oncology
• Surgery

Background:

• Methylene blue is used intraoperatively to identify insulin-secreting pancreatic tumors.
• Normal hemoglobin and red blood cell function are assumed for safe administration.

Observation:

• A patient with normal hemoglobin undergoing surgery for pancreatic adenoma received methylene blue.
• Methemoglobin levels increased significantly from 0.6% to 7.1% post-administration.

Findings:

• Methylene blue administration can cause a substantial rise in methemoglobin concentration.
• This effect poses a significant risk in patients with pre-existing hemoglobinopathies or metabolic pathway defects.

Implications:

• Careful patient selection is crucial when using methylene blue in surgical settings.
• Alternative diagnostic methods may be warranted for patients with unstable hemoglobins or hexose monophosphate pathway abnormalities.