Which of the following is not among the functions of the national reference laboratories?

The national reference laboratories play a crucial role in public health by supporting diagnostic testing and ensuring the accuracy and reliability of laboratory results across the healthcare system. Among their primary functions are the provision of referral services, evaluation of diagnostic kits and reagents, and implementation of external quality assurance programs.

The function of issuing licenses to operate a clinical laboratory is typically handled by regulatory bodies or government health departments, rather than national reference laboratories. This responsibility ensures that clinical laboratories meet specific standards and regulations necessary for their operation, which is distinct from the role of national reference laboratories that focus on providing expertise, technical guidance, and oversight in diagnostic testing and quality assurance. Therefore, the correct answer is that issuing licenses to operate a clinical laboratory is not among the functions of national reference laboratories.