Sickle Cell Anaemia Blood Test: What It Is, Screening & Results Explained

What Is Sickle Cell Anaemia?

Sickle cell anaemia (SCA) is an inherited blood disorder caused by a mutation in the HBB gene, which produces the beta-globin chain of haemoglobin. The mutation causes haemoglobin S (HbS) to form, which polymerises under low-oxygen conditions, distorting red blood cells into a rigid sickle (crescent) shape. These sickled cells block small blood vessels, causing painful crises, organ damage, and chronic haemolytic anaemia.

Sickle cell disease follows autosomal recessive inheritance: carriers (sickle cell trait, HbAS) have one normal and one sickle gene and are usually asymptomatic, while affected individuals (HbSS) have two sickle genes. The trait is most common in people of African, Caribbean, Middle Eastern, and South Asian heritage — populations where malaria has historically been endemic, as HbAS carriers have partial malaria resistance.

Why Is Sickle Cell Testing Done?

• Newborn screening — all UK newborns are screened for sickle cell disease as part of the heel prick test
• Pre-conception and antenatal screening — NICE recommends carrier screening for couples from high-risk ethnic groups
• Unexplained anaemia — sickle cell trait can occasionally cause mild anaemia or haematuria
• Family history — carrier detection for genetic counselling
• Before general anaesthesia — sickle cell trait requires precautions during surgery to prevent sickling under low oxygen

Test Types and Results

Testing is by haemoglobin electrophoresis or high-performance liquid chromatography (HPLC), which separates different haemoglobin types.

Sickle Cell Trait vs Sickle Cell Disease

• Sickle cell trait (HbAS) — carriers have approximately 40% HbS and 60% HbA; they are usually well but may experience problems at extreme altitude, during intense dehydration, or under general anaesthesia
• Sickle cell disease (HbSS) — affected individuals have predominantly HbS, causing chronic anaemia (Hb 60–90 g/L), painful crises, increased infection risk, stroke risk, and progressive organ damage

Management and Support

• Specialist care — all sickle cell patients should be managed by a haematology team
• Hydroxycarbamide (hydroxyurea) — increases foetal haemoglobin (HbF), reducing sickling frequency
• Pain management — prompt treatment of vaso-occlusive crises with adequate analgesia
• Vaccination — pneumococcal, meningococcal, and annual influenza vaccines are essential
• Prophylactic penicillin — lifelong in children, at least until age 5
• Folic acid supplementation — 5 mg daily to support red cell production
• Genetic counselling — crucial for carrier couples planning pregnancy

When Should You Get Tested?

• You are of African, Caribbean, Middle Eastern, or South Asian heritage
• You and your partner are planning pregnancy and want carrier screening
• You have unexplained anaemia, episodes of severe pain, or splenomegaly
• Before surgery requiring general anaesthesia if your status is unknown

Which Lola Health Tests Include Sickle Cell Screening?

Sickle cell anaemia screening is available as an add-on test with any Lola Health blood test. Haemoglobin electrophoresis provides a definitive result identifying HbAA, HbAS, HbSS, HbSC, and other variant haemoglobins.