Call the Midwife shines a light on many lesser-known illnesses and medical conditions, and now it's the turn of haemochromatosis – which makes an appearance in series nine. (Spoilers ahead for episode 2!)
What is haemochromatosis?
Put simply, haemochromatosis is a condition where too much iron builds up in your body – causing "iron overload". Left untreated, it can lead to major problems in the body's organs, as we see in poor Mrs Watkins (Amanda Root).
Normally, a person's intestines absorb just the right amount of iron from the food we eat. It is vital to get enough iron, as it helps make red blood cells to carry oxygen around the body; iron-rich foods include meat, beans, nuts, dried fruits, and leafy green vegetables.
However, people with this condition absorb too much iron. The body has no way to get rid of it, and so it stores the iron in the joints and the organs – especially the liver, heart, and pancreas.
Haemochromatosis is a genetic condition which runs in families, and is more common in people of northern European descent.
What are the symptoms?
Haemochromatosis tends to develop earlier in men. In women, it often shows up when they are past menopause, because in the years when they were menstruating they were able to lose iron during periods (and sometimes childbirth).
Symptoms include pain in the joints (especially in the fingers), feeling tired (fatigue), weight loss, pain and swelling in the belly, loss of sex drive and body hair, heart problems, and foggy memory.
If the condition is left untreated, it can also lead to liver problems (including cirrhosis), diabetes, arthritis and abnormal heart beat (arrhythmia).
As we see in Call the Midwife, haemochromatosis may also result in jaundice: the skin turning grey, bronze or yellow, and a yellowing of the eyes.
How is the condition diagnosed?
The condition is identified via blood tests.
Doctors will check the amount of iron in the blood (the transferrin saturation level) and the amount of iron stored in the body (the serum ferritin level), and whether the person's DNA carries a faulty HFE gene.
Two inherited copies of the faulty HFE gene will mean that a person is at risk of developing haemochromatosis, although not all of them will do so.
What is the treatment?
For those diagnosed with the condition, there is no cure. However, there are treatments.
The most common is phlebotomy (a medically-sound version of bloodletting), where blood is regularly removed from the patient; this forces the body to use up more of its iron excess to replace missing red blood cells.
Few lifestyle changes are required – but the NHS says affected patients are often advised to have a balanced diet, avoid cereals "fortified" with iron, give up iron and vitamin C supplements, and be careful not to drink too much alcohol.
More information is available via the NHS and the charity Haemochromatosis UK.
Call the Midwife continues on Sundays at 8pm on BBC One