The Editorial Executive Committee welcomes letters, which should be less than 250 words. Before a decision to publish is made, letters which refer to a published article may be sent to the author for a response. Any letter may be sent to an expert for comment. When letters are published, they are usually accompanied in the same issue by their responses or comments. The Committee screens out discourteous, inaccurate or libellous statements. The letters are sub-edited before publication. Authors are required to declare any conflicts of interest. The Committee's decision on publication is final.

Letter to the Editor

Editor, – In the article on magnesium by Dr Wu and Dr Carter (Aust Prescr 2007;30:102-5) there is little attempt to address the issue of cramps and magnesium ingestion by the public. My clinical experience has been that every aged patient who has any problem with cramping, has either tried, or is on, oral magnesium usually from the supermarket or health store. This is often magnesium phosphate.

Could the authors comment on the issue of cramping and adults over the age of fifty years? Is there any evidence that lack of magnesium causes this, or that oral magnesium is of any benefit?

Chris Commens
Dermatologist
Pennant Hills, NSW

Authors' comments

Dr J Wu and Dr A Carter, authors of the article, comment:

In response to Professor Commens, a literature search performed in consultation with our pharmacology unit failed to raise any conclusive evidence that magnesium phosphate is useful in preventing cramps in the elderly. This is not to say that biochemically proven hypomagnesaemia would not respond to supplementation, in the same way as hypocalcaemia or hypokalaemia would require calcium or potassium supplementation respectively.