Sir.—The advantages of an internationally uniform and internally consistent system of measurement as promised by the International System of Units (SI) are evident to many in the profession. For the clinical pathologist and the research scientist, such a system eases calculations and enhances international dialogue. Even in Europe, where the system was first initiated, its acceptance has not been universal, and various exceptions have been suggested.1-3
Dr Powsner2 has noted that in certain areas there are substantial hurdles to be overcome if the use of SI units is to be implemented, but he states that in pharmacy, the conversion is merely an arithmetic calculation. However, the issue is not as simple as he implies, is not without risk, and offers no advantage over the already internationally accepted metric system.
Inasmuch as the SI system (mole) and the metric system (gram) are related by a constant (the molecular