Feeling tired and breathless can be chalked up to a whole host of reasons but one key one is easy to sort out - if it is diagnosed. Figures show millions of people are deficient in iron, a vital mineral, which can have serious repercussions on their health. It is believed that a quarter of the world's population may suffer from the condition which means they have too little iron in their blood, according to the Institute for Health Metrics and Evaluation.

In the UK it is believed there are about four million people with the condition, mainly women of reproductive age. Its most severe form is thought to affect 8% of women and 3% of men.

Symptoms can include fatigue and shortness of breath. If it goes untreated it can progress to anaemia, where people have a low red blood cell count which can cause more serious heart and health problems.

The NHS warns it can also cause lung problems and have an effect on the immune system increasing the risk of infection and illness. For pregnant women it can cause a greater chance of complications both before and after the birth.

However, once diagnosed, it is often easy to treat with a supplement or a change in diet to eat more iron-rich foods. It can be identified by a simple blood test which measures ferritin - a protein in the blood that stores iron.

While this is not part of a routine checkup in most countries, including the United States, in the UK it can form part of standard blood check. However, the World Health Organisation has, for decades, given 15 micrograms per litre of ferritin as the threshold for low iron, which some experts say is too low which means it does not reflect the true prevalence of iron deficiency.

George Goshua, MD, MSc, an assistant professor of medicine (medical oncology and hematology) at Yale School of Medicine warns this can leave many symptomatic individuals without access to treatment. He says: "We know for a fact that we’re missing people who are truly iron deficient."

He led a team which looked at the benefits and costs of screening adult women for iron deficiency. Its findings were recently published in the American Journal of Hematology.

Iron deficiency is common but curable

Figures from across the world she the issue may impact as many as 2 billion people. But this could be tackled with a simple solution. Dr Goshua said: "This is a problem that’s actually pretty easy to solve. We know exactly what iron does, and we know what deficiency looks like.”

Most of the iron in the human body becomes haemoglobin, a protein found in red blood cells that binds and transports oxygen to cells and tissues. The mineral is absorbed from food, meaning that poor nutrition and issues with nutrient absorption due to disease or gastrointestinal disorders can deplete iron levels. Iron deficiency happens when the red blood cells are unable to make enough haemoglobin to meet the body’s demand for oxygen.

This results in people often experiencing fatigue, shortness of breath, changes in mood, and restless legs. Dr Goshua says these are “the kinds of things that have historically been normalised.”

Over time, iron deficiency can progress into anaemia. But, by the time anaemia presents, a person may have experienced “months or years of unnecessary symptomatology,” he warns.

Symptoms of iron deficiency anaemia

There are some common signs which are red flags for iron deficiency and some less frequent ones. According to the NHS these are:

Common symptoms of iron deficiency anaemia can include:

• tiredness and lack of energy
• shortness of breath
• noticeable heartbeats (heart palpitations)
• paler than usual skin
• headaches

Less common symptoms of iron deficiency anaemia (that are not usually connected to pregnancy) include:

• hearing ringing, buzzing or hissing noises inside your head (tinnitus)
• food tasting strange
• feeling itchy
• a sore tongue
• hair loss – you notice more hair coming out when brushing or washing it
• wanting to eat non-food items, such as paper or ice (pica)
• finding it hard to swallow (dysphagia)
• painful open sores (ulcers) in the corners of your mouth
• nail changes, such as spoon-shaped nails
• restless legs syndrome

Treatment

Treatment can either be by taking an iron supplement and/or eating iron-rich foods. It says: "Once the reason you have iron deficiency anaemia has been found (for example, an ulcer or heavy periods) the GP will recommend treatment.

"If the blood test shows your red blood cell count is low, iron tablets will be recommended to replace the iron that's missing from your body. You'll need to take them for about 6 months. Drinking orange juice after you've taken a tablet may help your body absorb the iron."