Case 2 : sickle cell disease Flashcards
1
Q
Sickle cell disease
A
- Name for a group of inherited conditions that affect rbcs.
- Most serious type is called sickle cell anaemia.
- Sickle cell disease is particularly common in people with an African or Caribbean family background.
- People with sickle cell disease produce unusually shaped rbcs that can cause problems because they do not live as long as healthy blood cells and can block blood vessels. People with scd do not make Hb properly. Normal rbcs are flexible and disc-shaped, but in sickle cell disease they can become rigid and shaped like a crescent or sickle because the haemoglobin inside them clumps together.
- Sickle cell disease is a serious and lifelong health condition, although treatment can help manage many of the symptoms.
- Overall, the life expectancy for someone with sickle cell disease tends to be shorter than normal, but varies depending on the exact type of sickle cell disease they have, how it’s treated and what problems they experience.
2
Q
Symptoms of sickle cell disease:
A
- People born with sickle cell disease tend to have problems from early childhood, although some children have few symptoms and lead normal lives most of the time.
The main symptoms of sickle cell disease are:
- painful episodes called sickle cell crises, can be very severe, last up to a week
- increased risk of serious infections
- anaemia (where rbcs cannot carry enough O around the body), which can cause tiredness and shortness of breath
- Some people also experience other problems, such as delayed growth, strokes and lung problems.
3
Q
Painful episodes or sickle cell crises
A
Episodes of pain known as sickle cell crises are one of the most common and distressing symptoms of sickle cell disease.
- They happen when blood vessels to part of the body become blocked.
- pain can be severe and lasts for up to 7 days on avg
- sickle cell crisis often affects a particular part of the body, such as the:
hands or feet (particularly in young children)
ribs and breastbone
spine
pelvis
tummy
legs and arms
- How often someone with sickle cell disease gets episodes of pain varies. Some people may have one every few weeks, while others may have less than 1 a year. The average is 1 bad episode a year.
- It’s not always clear what triggers bad pain, but sometimes painful episodes can be caused by the weather (such as wind, rain or cold), dehydration, stress or strenuous exercise.
4
Q
Infections as result of sickle cell disease
A
- Ppl with scd more vulnerable to infections, particularly when they’re young.
- Infections can range from mild, such as colds, to much more serious and potentially life threatening, such as meningitis.
- Vaccinations and daily doses of antibiotics can help reduce the risk of many infections.
5
Q
Anaemia as result of scd
A
- Nearly all those with scd have anaemia, where the hb in the blood is low.
- does not usually cause many symptoms, but sometimes it can get worse if you become infected with the virus that causes slapped cheek syndrome(parvovirus).
- This can lead to a sudden drop in the number of rbcs and may cause additional symptoms, such as headaches, a rapid heartbeat, dizzinessand fainting.
- It’s usually treated with a blood transfusion.
6
Q
Other problems associated with scd
A
- delayed growth during childhood + delayed puberty
- gallstones, can cause tummy (abdominal) pain and yellow skin and eyes (jaundice)
- bone and joint pain
- a persistent and painful erection of the penis (priapism), can sometimes last several hours
- painful open sores on the lower legs (leg ulcers)
- strokes or transient ischaemic attacks,( flow of blood to the brain is blocked)
- serious lung condition: acute chest syndrome, which can cause a fever, cough, chest pain and breathing difficulties
- swelling of the spleen, which can cause shortness of breath, a rapid heartbeat, tummy pain, a swollen tummy and anaemia
- eyesight problems, such as floaters, blurred or patchy vision, reduced night vision and occasionally sudden vision loss
- high blood pressure in the blood vessels that carry blood from the heart to the lungs (pulmonary hypertension)
- kidney or urinary problems, including blood in the urine and bedwetting
7
Q
Causes of scd
A
- caused by a gene that affects how rbcs develop.
- child’s parents often will not have scd themselves and they’re only carriers of the sickle cell trait.
- To be born with sickle cell disease, a child has to inherit a copy of the sickle cell gene from both their parents.
- This usually happens when both parents are “carriers” of the sickle cell gene, also known as having the sickle cell trait.
- Or it can happen when 1 parent has sickle cell disease and the other is a carrier of it.
- If both parents are sickle cell carriers, there’s a:
- 1 in 4 chance each child they have will not inherit any sickle cell genes and will not have sickle cell disease or be able to pass it on
- 1 in 2 chance each child they have will just inherit a copy of the sickle cell gene from 1 parent and be a carrier
- 1 in 4 chance each child they have will inherit copies of the sickle cell gene from both parents and will be born with sickle cell disease
8
Q
Screening for scd
A
- A simple blood test will show whether you’re a carrier
- done routinely during pregnancy and after birth, but have test at any time.
- all babies offered newborn blood spot test (heel prick test), can help to:
- indicate whether baby has scd
- show if baby has the sickle cell trait
- pick up certain other inherited conditions, such as cystic fibrosis
If newborn screening suggests baby may have sickle cell disease, a second blood test will be carried out to confirm the diagnosis.
Testing for sickle cell carriers
- A blood test can be done at any time to find out if you carry sickle cell and are at risk of having a child with sickle cell disease.
- This is also known as having the sickle cell trait.
9
Q
Treatments for scd
A
- People with sickle cell disease need treatment throughout their lives.
- It’s also important for people with sickle cell disease to look after their own health using self care measures, such as by avoiding triggers and managing pain.
A number of treatments for sickle cell disease are available eg
- drinking plenty of fluids to prevent dehydration and staying warm to prevent painful episodes
- avoid sudden temperature changes, such as swimming in cold water
- painkillers, such as paracetamol or ibuprofen (sometimes treatment with stronger painkillers in hospital)
- distractions to take your mind off the pain
- daily antibiotics, Long-term use of antibiotics will not pose any serious risks to your health, and having regular vaccinations to reduce your chances of getting an infection
- For sickle cell related anaemia dietary supplements like folic acid, which helps stimulate the production of red blood cells, may sometimes be required to help improve anaemia if your child has a restricted diet, such as a vegetarian or vegan diet.
- a medicine called hydroxycarbamide (hydroxyurea) to reduce symptoms, it can lower the amount of other blood cells, such as white blood cells and platelets (clotting cells), so you’ll usually have regular blood tests to monitor your health.
- regular blood transfusions if symptoms continue or get worse, or there are signs of damage caused by sickle cell disease
- an emergency blood transfusion if severe anaemia develops
10
Q
Cure for scd
A
- The only cure for sickle cell disease is a stem cell or bone marrow transplant, but they’re not done very often because of the risks involved.
- Stem cells are special cells produced by bone marrow.
- For a stem cell transplant, stem cells from a healthy donor are given through a drip into a vein.
- These cells then start to produce healthy red blood cells to replace the sickle cells.
- A stem cell transplant is an intensive treatment that carries a number of risks.
- The main risk is graft versus host disease, a life-threatening problem where the transplanted cells start to attack the other cells in your body.
- Stem cell transplants are generally only considered in children with sickle cell disease who have severe symptoms that have not responded to other treatments, when the long-term benefits of a transplant are thought to outweigh the possible risks.
11
Q
Treating other problems associated with scd
A
- hormonal medicine - trigger puberty in children with delayed puberty
- gallstones - gallbladder removal surgery
- bone and joint pain - painkillers, more severe cases may require surgery
- persistent and painful erections (priapism) - medication to stimulate blood flow or using a needle to drain blood from the penis
- leg ulcers - cleaning the ulcer and dressing it with a bandage
- increased risk of having a stroke, or have had a stroke - regular blood transfusions or treatment with hydroxycarbamide
- acute chest syndrome, serious lung condition, -emergency antibiotics, blood transfusions, oxygen and fluids given into a vein – hydroxycarbamide may be needed to prevent further episodes
- People who need a lot of blood transfusions may also need to take medicine called chelation therapy. This reduces the amount of iron in their blood to safe levels.
12
Q
Sickle cell anaemia
A
A carrier of sickle cell is someone who carries the gene that causes sickle cell disease but does not have sickle cell disease themselves. It’s also known as having the sickle cell trait.
People with the sickle cell trait will not develop sickle cell disease, but are at risk of having a child with it if their partner is also a carrier.
13
Q
Ideas, concerns and expectations
A
- Ideas : unemotional thoughts about the nature, cause and likely course of any change in bodily function that catches our attention. Some ideas may trigger a health-seeking response; for example, a person with a severe sore throat may develop the idea that she needs antibiotics.
- Concerns are the emotional triggers and fears that we all experience to varying degrees. Patients who go to their doctor with headaches tend to have a higher level of concern than those who do not. Concerns may relate to seriousness or implications for the future, or are more commonly an unfocused cloud of multiple unpleasant feelings and fears.
- Expectations of the doctor’s likely reaction, be it therapeutic, advisory or referral to another agency, derive from patients’ representation of their problem and their experience of medical care. They govern patients’ approach to matters such as whether they wish to be involved in making choices about their care, and how much information they want to receive. Expectations are closely intertwined with agendas
14
Q
Tasks in consultation
A
- Understand the problem
- Understand the patient
- Share understanding
- Share decisions and responsibility
- Maintain the relationship
15
Q
Qs for learners to ask themselves
A
- Do I know significantly more about the patient than I did before he came through the door? Was I curious?
- Did I really listen?
- Did I find out what really mattered?
- Did I explore his agenda, beliefs and expectations? Did I make an acceptable working diagnosis?
- Did I use what he thought when I started explaining?
- Did I give him the opportunity to be involved in decisions? Did I explore his understanding of the treatment?
- Did I make an attempt to determine that he really understood? Did we agree?
- Was I friendly?
16
Q
How does hydrophobic pocket form in sickle cell hb
A
- The protein is made of four subunits (two alpha chains and two beta chains).
- Each subunit has a haem at its oxygen binding site
- In sickle cell hb, a single mutation causes the 6th amino acid of the beta chains to be a valine instead of a glutamate.
- Glutamic acid is polar and so is hydrophilic and will make bonds with H20, valine is non polar and so is hydrophobic, will not want to make bonds with water, forms a microenvironment which excludes water, so this pocket is hydrophobic.
- These valines are located on the outside surface of the protein. In normal hb, the glutamate in this position hydrogen bonds with water to help keep the protein in solution.
- In sickle cell hemoglobin, the non-polar valine on the surface of one protein embeds itself in a hydrophobic pocket of an adjacent hemoglobin, forming a haemoglobin dimer.
- The other val-6 side chains in the protein are positioned to bond to other hb proteins, causing long chains of deoxygenated hb polymers form in the rbcs. These polymers can not transport oxygen effectively and distort the shape of the rbcs to a sickle shape.
- REview
27
Q
Laboratory features of sickle cell disease
A
- Hb low (typically 60 - 80 g/l)
- Reticulocytes usually high (high cell turnover because premature destruction in haemolysis)
- Blood film
- Sickled cells (crescent shape)
- Boat cells (look like boats)
- Target cells (dougnuts)
- Howell Jolly bodies (contain purple dots - DNA remnants from nuclei which have not been removed)
