Hormones often get the blame when teenagers experience mood issues – but iron deficiency is incredibly common, especially in adolescent girls – and there’s a very strong link with mental health.
Dr Emi Khoo, a gastroenterologist and clinical researcher at Brisbane’s Mater Hospital, says iron is crucial to brain health and function, and adolescent females may be particularly at risk as they start menstruation.
Evidence has accumulated over the last two decades, showing that iron impacts more than just oxygen transport, cellular respiration and metabolism, Dr Khoo says.
“Iron is required for behavioural organisation as well. When you have a deficiency in iron it leads to poor brain myelination… It will affect glutamate and GABA haemostasis which is modified by changes in our brain iron status.”
“Such changes not only produce deficits in memory and learning capacity, but they also affect motor skills and emotional and psychological wellbeing as well,” Dr Khoo says.
Low iron can also cause anxiety, depression and mood instability, and negatively affect cognition.
Iron is needed to synthesise fatty acids and cholesterol which are essential to produce norepinephrine and dopamine neurotransmitters.
“Iron deficiency has been reported to cause behavioural and developmental symptoms because it affects transmitter production like serotonin, noradrenaline and dopamine, and all this activity in neurons can affect brain function and cognitive learning in school,” Dr Khoo says.
There are multiple pathways involved, affecting energy metabolism, muscle function, sleep and fatigue levels, as well as the immune system.
And because iron is central to the mitochondrial respiratory chain, iron deficiency can also lead to poor energy levels and fatigue which can impact on academic results, exercise and extracurricular activities—and quality of life and psychological health.
Baseline iron studies and full blood count (especially haemoglobin level) are recommended if iron deficiency is suspected. Serum ferratin is most useful, and transferrin saturation is also helpful to see much iron is being transported. Iron serum levels are less accurate because they fluctuate.
“Serum ferritin is the most important indicator because it indicates how much iron is stored in our organs,” Dr Khoo says.
There are, however, some important caveats.
“In the acute inflammatory state, a serum ferritin may not be as accurate because it’s also an active inflammatory process, which means that if a CRP is high, you really require ferratin to be above 100 to say that they have a normal iron storage,” Dr Khoo explains.
“Anything below 100 and they are considered iron deficient within the background inflammatory burden.”
Heavy menstruation and poor nutrition are the two most common causes of iron deficiency in teenagers.
Dr Khoo recommends asking about daily dietary intake.
“We know that young people like fast food, McDonald’s, KFC, all that obviously doesn’t contain much nutrition at all,” she says.
Iron deficiency is also overrepresented in people with restrictive eating disorders such as anorexia nervosa or bulimia. Interestingly, iron deficiency often occurs when the person is eating better, because they need more iron to build their blood volume as they gain weight.
Are they malnourished?
Iron deficiency is a marker of malnutrition. Dr Khoo says it is particularly concerning if iron deficiency is seen in men at any age, elderly women, or if there is concurrent sign of rectal bleeding.
The cause for iron deficiency must be assessed for:
Is there anything impacting on absorption?
Are they losing iron from somewhere?
For example, heavy menstrual bleeding, gastric ulcer/angiectasia or bleeding from their rectum.
Do they have a chronic infection, inflammation, or any diseases or malignancy that requires more iron than usual?
Dr Khoo recommends an endoscopy, even for those with heavy menstrual period —especially if they also have concurrent gut issues or rectal bleeding.
“In the past, we tended to ignore rectal bleeding in the young population, assuming it was related to hemorrhoidal bleeding. However, we are seeing more and more colorectal cancer in the young age group lately. So, there’s no harm in getting it checked out earlier than later.”
Treatment choice for teenagers depends on the severity of the deficiency, and any other comorbidities.
Generally oral supplements are the first line treatment—particularly formulations that contain vitamin c as that helps with absorption of iron into organs. However abdominal discomfort and constipation are common side effects from oral supplement. In this case, intravenous iron should be considered.
Dr Khoo says strategies such as second-daily prescribing would only be effective in those with mild deficiency—but in those cases she tends to recommend an iron-rich diet over supplements.
IV iron supplements may be needed in severe cases where ferritin is almost undetectable or if they have underlying medical conditions such as chronic kidney disease or an inflammatory bowel condition.
Athletes, particularly female athletes that participate endurance sports, have high rates of compromised iron status due to the heightened iron loss through menstruation and exercise induced mechanisms associated with endurance activity.
For female athletes, iron-rich diets that include meat, poultry, seafood, wholegrains, seeds and legumes are recommended over supplements for prevention of low iron status—both because they are better tolerated and because they are absorbed and maintained better by the body.
“In the past we would suggest oral supplements in iron deficiency, but this approach has lately been criticised because of the side effects with the use of supplements.”
Girls who do a lot of sport, particularly endurance sports, may need regular monitoring for their iron studies on blood test, she adds. If it’s close to borderline, she recommends an iron-rich diet and referral to a dietitian.
Note that there are two types of dietary iron: haem and non-haem food. Heam is only found in animal flesh, such as meat, poultry and seafood. Plant foods contain only non-haem iron. This is found naturally in iron-fortified wholegrain cereals and breads, cashew nuts, seeds, beans, dark leafy vegetables, legumes and dried fruit. Haem iron is better absorbed by the body than non-haem iron.
Vegetarian and vegans are at risk of iron deficiency if they don’t consume well-planned meals with a wide variety of plant foods, including vitamin C, which assist in iron absorption. Diet alone is not generally adequate to replace iron stores in a patient diagnosed with iron deficiency.
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