There are several chemicals that are thought to be associated with the development and symptoms of RLS. One is of course dopamine, a chemical crucial for movement, thought process as well as motivation.
Another chemical that seems to be very important for the development of RLS is iron. In the brain cell systems, iron helps with the actions of dopamine and is known as a co-factor. In the evening and night, when the symptoms of RLS are most pronounced, both iron and dopamine levels show a “dip”, known as the circadian variation. We know that RLS can also develop during pregnancy, typically in the last three months, a time when iron levels can be low. RLS is also associated with people who develop iron deficiency anaemia, sometimes due to heavy menstrual periods for instance.
It is for this reason that measurement of iron in blood tests is important for RLS and should be done in every case of RLS. An association between RLS and iron deficiency in the blood has been long recognised. In fact, it was back in 1950 when Karl Ekbom noted that about 25% of RLS patients had an iron deficiency. Studies have also shown that abnormalities of brain iron storage and transport are strongly associated with RLS.
But the simple measurement of iron in blood will not suffice. In the clinic, measurement of a protein called ferritin has been used to assess iron status in RLS patients. Ferritin measurement provides a useful measure of iron storage, as iron binds to this protein. Low ferritin values indicate low iron storage in the body and brain, and decreased availability of iron in the brain of RLS patients. Measurement of ferritin levels is more accurate than measurement of iron in the blood as iron levels can be variable and fluctuate. Two independent studies reported that while blood iron values in patients with RLS compared to healthy controls were normal, ferritin levels were reduced in the RLS patients.
Iron levels may be normal even if you have a deficiency of iron and iron levels in the blood can be affected by diet, stress as well as the pattern of sleep.
So what does all of this mean for all of those who suffer from RLS? It means that you must have your ferritin level in the blood checked at regular intervals. What is considered a ‘normal value’ of ferritin level varies from laboratory to laboratory and so normal levels will be defined by your local laboratory range. If the ferritin level is low or at the lower range of this normal value, it is reasonable to have a trial of treatment with oral iron tablets and recheck the ferritin levels to make sure this has normalised.
Please be mindful however that too much iron supplementation is not good and the ferritin levels also need to be monitored to ensure that iron replacement is not overdone. The replacement of iron may, in some cases, treat the symptoms of RLS very effectively.