Sickle cell disease: understanding crises, treatment and what carrier status means

What is sickle cell disease?

Sickle cell disease is a genetic disorder affecting haemoglobin (Hemoglobin), the protein inside red blood cells that carries oxygen. The defect makes the haemoglobin molecule unstable when oxygen levels fall, causing red blood cells to distort into a rigid, crescent or sickle shape instead of their normal flexible disc. The disease follows an autosomal recessive inheritance pattern, meaning a person needs two defective copies of the gene to have the full disease.

These misshapen cells are fragile and short-lived, surviving weeks rather than the normal 120 days, which causes chronic anaemia. Their more immediately dangerous property is that they jam in small blood vessels, cutting off oxygen to the tissue beyond. This blockage is called a vaso-occlusive crisis and is the source of the severe pain that defines the disease.

The disease is most common in populations historically exposed to malaria, because the sickle trait offers partial protection against severe malaria. In the Arabian Gulf, particularly the Eastern Province of Saudi Arabia, Bahrain, Oman, parts of Kuwait and Yemen, the frequency of sickle trait carriers is among the highest in the world.

There is more than one form of sickle cell disease. The most common and severe is HbSS, where a person inherits two sickle copies. Other forms include HbSC and HbS-beta-thalassemia, all of which cause sickle-related symptoms with varying severity. Genetic testing identifies the precise form and informs what to expect over time.

Prevalence in Saudi Arabia and the wider Gulf

A 2011 study published in the Journal of Epidemiology and Global Health by Memish and colleagues analysed the results of Saudi Arabia's premarital screening programme and found striking regional variation. The Eastern Province had the highest rates of sickle trait carriers, with some communities exceeding 30%. By contrast, the Najd and Northern regions showed much lower rates.

At the Gulf level, Bahrain and Oman also show elevated frequencies compared with the global average. In Yemen and the southern Arabian Peninsula the disease is present but precise data are scarcer. In the Levant, Syria, Jordan and Lebanon have meaningful carrier frequencies but generally lower than the Gulf.

Saudi Arabia's premarital screening programme, which began in 2004, was evaluated in a follow-up study by the same researchers published in Annals of Saudi Medicine in 2011, which found measurable reductions in births of children with full sickle cell disease over six years of the programme.

What triggers a pain crisis?

A pain crisis occurs when rigid sickle cells cluster in small blood vessels, blocking them and starving the tissue they supply of oxygen. The pain is typically throbbing or burning and can affect bones, joints, the chest and the abdomen. In very young children the first sign is often a painful swelling of the hands and feet called hand-foot syndrome.

Some triggers can be reduced with awareness and planning. Dehydration thickens the blood and sharply raises the risk of sickling, so adequate fluid intake throughout the day is non-negotiable for someone with sickle cell disease. Cold causes blood vessels to constrict, creating more opportunity for obstruction. Heavy exertion, extreme heat, high altitude and emotional stress are all documented triggers.

Infection is one of the most dangerous triggers. Sickle cell patients are particularly vulnerable to encapsulated bacteria such as Streptococcus pneumoniae, which is why vaccination against pneumococcal disease, influenza and meningitis is essential rather than optional. Young children with sickle cell disease routinely receive daily prophylactic penicillin for the first several years of life to reduce the risk of overwhelming bacterial infection.

Longer-term complications to watch for

Beyond pain crises, sickle cell disease can damage multiple organs over time. Stroke affects roughly 11 percent of children with the disease before the age of 20 without adequate treatment, leaving lasting disability. Transcranial Doppler ultrasound, which measures blood flow velocity in the brain, identifies children at elevated risk before a stroke occurs, allowing preventive transfusion therapy to begin.

Acute chest syndrome is a medical emergency that resembles severe pneumonia. It presents with chest pain, fever and falling oxygen levels and is one of the leading causes of death in sickle cell disease. Recognising it as an emergency and not a passing episode is essential.

The kidneys, eyes, joints, liver and, in men, the reproductive system can all be affected over years. Regular review of these organ systems is part of ongoing specialist care, not an optional extra.

Hydroxyurea: how it reduces crises

Hydroxyurea is the most widely used long-term treatment for sickle cell disease. Its main mechanism is stimulating the body to produce fetal haemoglobin (HbF), a form of haemoglobin that does not sickle and dilutes the abnormal HbS. The practical result is fewer pain crises per year, less need for blood transfusion and lower rates of acute chest syndrome.

A 2024 review in Expert Review of Clinical Pharmacology described hydroxyurea as the cornerstone of sickle cell management in the modern era, with evidence of reduced early mortality and improved quality of life. The drug takes time to show its full effect, typically three to six months of consistent use, and benefits accumulate over years. It is important to persist through this initial period and not judge the drug's effect too early.

Because hydroxyurea suppresses overall blood cell production, patients need regular full blood counts (CBC) to ensure white blood cells and platelets stay within safe limits. Never stop taking hydroxyurea without your doctor's guidance, even if you feel well, because abrupt discontinuation can bring crises back quickly.

Newer approved treatments exist for patients who do not respond adequately to hydroxyurea. A haematologist reviews these options individually, factoring in each patient's response to current treatment and the availability of newer agents in their region. The field is moving quickly and options are expanding.

Carrier status and what it means for family planning

A sickle cell trait carrier has inherited one copy of the sickle gene from one parent and one normal copy from the other. They are generally healthy, do not experience pain crises and do not have chronic anaemia. The body produces enough normal haemoglobin to compensate for the abnormal fraction.

In rare circumstances carriers may experience symptoms under extreme conditions: very high altitude, severe dehydration or extreme sustained physical exertion. These are uncommon and do not mean the person has the full disease, but awareness is useful in relevant occupational or sporting contexts.

The greatest importance of knowing your carrier status comes when planning a family. If both partners carry the sickle trait, each pregnancy has a 25 percent chance of producing a child with full sickle cell disease, a 50 percent chance of a carrier like the parents, and a 25 percent chance of an unaffected child. These are the figures a genetic counsellor works through with a couple before they make decisions.

Managing pain at home and knowing when to go to hospital

Not every pain crisis requires hospital admission. A mild to moderate crisis can often be managed at home with aggressive oral hydration, rest and pain relief prescribed by your doctor. Dehydration prolongs a crisis, so drinking fluids consistently even during pain is important. Evidence suggests patients who maintain an intake of around three litres of water daily experience fewer and less severe crises.

What requires going to hospital is fever, pain that does not respond to your home medicines within two hours, or any of the danger signs listed above. Fever in a sickle cell patient is treated as a potential serious bacterial infection until proven otherwise, because these patients have a markedly higher risk of sepsis than the general population. Aim to reach the emergency department within an hour of fever onset rather than waiting to see whether it settles.

In the Gulf summer, avoid prolonged exposure to extreme heat and sudden shifts in temperature. Swimming in very cold water and then stepping into intense heat is a recognised crisis trigger. Travelling in air-conditioned cars at a moderate temperature setting is safer than experiencing temperature extremes.

Having a written pain plan from your specialist that specifies which medicines are safe at home and exactly when to go to hospital simplifies decisions for you and for the emergency team who may not know your history. Many patients carry a brief medical summary card that speeds appropriate treatment when they arrive.

Newborn screening and why early diagnosis matters

Newborn screening changes the trajectory of this disease. Children identified at birth and started on preventive care, including prophylactic penicillin and comprehensive vaccination, live significantly longer and with fewer serious complications than those diagnosed only after their first severe crisis. Early identification also allows families to learn about triggers and warning signs before an emergency occurs.

Premarital screening programmes across Saudi Arabia, the UAE, Bahrain and other Gulf states test couples for sickle trait and thalassemia before marriage. The screening does not prohibit marriage but gives both partners accurate information about the specific genetic risk to their future children, allowing informed decisions and access to genetic counselling.

Prenatal diagnosis is also available for couples where both are carriers and who want to know the genetic status of a pregnancy before birth. This is a personal decision that genetic counsellors support without directing, providing accurate information and options rather than a predetermined conclusion.

Screening before marriage is not a verdict on the future. Many couples in which both partners are carriers choose to marry after understanding the true level of risk and the options available for monitoring a pregnancy. The goal of screening is informed planning, not exclusion.

Sources

• Memish ZA, Owaidah TM, Saeedi MY et al: Marked regional variations in the prevalence of sickle cell disease and beta-thalassemia in Saudi Arabia: findings from the premarital screening and genetic counseling program, Journal of epidemiology and global health, 2011
• Memish ZA, Saeedi MY: Six-year outcome of the national premarital screening and genetic counseling program for sickle cell disease and beta-thalassemia in Saudi Arabia, Annals of Saudi medicine, 2011
• Darbari DS, Sheehan VA, Ballas SK et al: The vaso-occlusive pain crisis in sickle cell disease: Definition, pathophysiology, and management, European journal of haematology, 2020
• Yawn BP, Buchanan GR, Afenyi-Annan AN et al: Management of sickle cell disease: summary of the 2014 evidence-based report by expert panel members, JAMA, 2014
• Riley C, Kraft WK, Miller R et al: Hydroxyurea in the sickle cell disease modern era, Expert review of clinical pharmacology, 2024
• Inusa BPD, Hsu LL, Kohli N et al: Sickle Cell Disease-Genetics, Pathophysiology, Clinical Presentation and Treatment, International journal of neonatal screening, 2019
• World Health Organization: Sickle cell disease fact sheet