Normally in sport it is iron deficiency that gives cause for concern. But new research from Switzerland has uncovered a problem of apparent iron overload in professional road cyclists, posing equal if not greater risks to health.

In 1999, the International Sports Federation of Cycling (Union Cycliste Internationale, or UCI) introduced stringent medical testing for cyclists in the wake of major doping scandals. Four times a year, all professional road cyclists registered in a first or second category trade team are obliged to submit to a battery of blood tests and other checks, with the results fed into an ongoing survey.

The most obvious abnormality revealed by this survey was a high serum ferritin level in many athletes. A significant proportion of body iron is stored in serum ferritin, and ferritin values are accepted as a reasonably accurate measure of total iron stores.

In 1999, the average ferritin value of the 1,000-plus riders tested was 342ng/ml – significantly higher than the upper normal limit of 300ng/ml commonly used by laboratories. This finding was particular significant in light of the fact that ferritin levels tend to be lower in athletes than in sedentary people, with up to 10% of male athletes reported to have inadequate iron stores.

These high ferritin levels worried the UCI for two main reasons:

• Although iron is vital, it is highly toxic when not maintained within cells or bound to proteins, with excesses prone to deposit in various tissues, leading to organ dysfunction or even cancer;
• Excessive iron supplementation, as reported by these cyclists, is linked with blood doping. The use of recombinant human erythropoietin (rhEPO) to boost red blood cell production increases the need for iron. Furthermore, increasing body iron levels before rhEPO administration improves the results.

Nevertheless, as the researchers explain, high ferritin levels are not proof of blood doping since iron supplementation has long been part of the culture of cycling, arising from the belief that iron enhances performance by increasing the number of red blood cells (actually true only for those suffering from iron deficiency). The fact that ferritin levels were particularly high among older riders, who probably started to supplement at a time when medical supervision was minimal and the risks of overload less well appreciated, tends to underline the cultural hypothesis.

The good news is that since mandatory testing was introduced ferritin levels have fallen gradually, with average values decreasing by 33% between 1999 and 2002.

‘...cyclists with increased serum ferritin levels probably have an increased risk of developing cirrhosis, cancer, cardiovascular diseases and neurodegenerative disorders,’ warn the researchers.

‘The situation seemed to be improving slowly with time but is still worrying. The only way to improve the situation further is to continue the fight against doping and educate the athletes. Both aspects are closely related and are part of the health programme introduced by the UCI.’

Br J Sports Med 2004; 38:704-708