What to know about sickle cell anemia and hemoglobin Health ConditionsHealth ConditionsAlzheimer's & DementiaAnxietyArthritisAsthma & AllergiesBreast CancerCancerCardiovascular HealthCOVID-19Dermatology & SkincareDiabetesEnvironment & SustainabilityExercise & FitnessEye HealthHeadache & MigraineHealth EquityHIV & AIDSHuman BiologyInflammatory Bowel DiseaseLeukemiaLGBTQIA+Men's HealthMental HealthMultiple Sclerosis (MS)NutritionParkinson's DiseasePsoriasisSexual HealthWomen's HealthDiscoverNewsLatest NewsOriginal SeriesMedical MythsHonest NutritionThrough My EyesNew Normal HealthPodcastsHow to understand chronic painWhat is behind vaccine hesitancy?The amazing story of hepatitis C, from discovery to cureNew directions in dementia researchCan psychedelics rewire a depressed, anxious brain?Why climate change matters for human healthToolsGeneral HealthDrugs A-ZHealth HubsHealth ToolsBMI Calculators and ChartsBlood Pressure Chart: Ranges and GuideBreast Cancer: Self-Examination GuideSleep CalculatorHealth ProductsAffordable Therapy OptionsBlood Pressure MonitorsDiabetic SuppliesFitness TrackersHome GymsGreen Cleaning ProductsHow to Shop for CBDQuizzesRA Myths vs FactsType 2 Diabetes: Managing Blood SugarAnkylosing Spondylitis Pain: Fact or FictionConnectAbout Medical News TodayWho We AreOur Editorial ProcessContent IntegrityConscious LanguageNewslettersSign UpFollow UsMedical News TodayHealth ConditionsDiscoverToolsConnectSubscribe How does sickle cell anemia affect hemoglobin Medically reviewed by Jenneh Rishe, RN — By Zawn Villines on July 29, 2022Sickle cell disease (SCD) is a genetic disorder that causes red blood cells to take the shape of a sickle or a letter “C.” Levels of hemoglobin, a protein that helps carry oxygen on red blood cells, are also typically low. Red blood cells are typically round. When a person has SCD, abnormal types of hemoglobin cause their red blood cells to change shape. This change makes it harder for red blood cells to move through the body and carry oxygen throughout the body. Reduced oxygen and blood flow to vital organs, such as the kidneys, can cause pain and even life threatening illnesses. Low hemoglobin is common in people with SCD and can cause anemia. Sickle cell anemia is a form of SCD. Read on to learn more about how sickle cell anemia can affect the structure and levels of hemoglobin, as well as how doctors might diagnose and treat this disease. Hemoglobin levels in people with sickle cell anemia Hemoglobin levels in people with SCD are typically in the range of 6–11 grams per deciliter (g/dL), whereas they are around 12 mg/dL in people without SCD. Lower hemoglobin levels can make it more difficult for red blood cells to carry oxygen throughout the body. This can cause a wide range of symptoms, including pain and exhaustion. Over time, SCD may affect most organs, including the eyes, kidneys, and liver. In addition to causing low hemoglobin levels, SCD changes the hemoglobin, causing cells to sickle. These cells die early. Sickled cells are also more likely to stick together, which can increase the risk of dangerous blood clots and pulmonary embolism. Does sickle cell trait affect hemoglobin levels When a person has sickle cell trait, it means that they carry one gene for SCD, not two. Sickle cell trait is usually a benign condition that does not affect health or hemoglobin levels. Because people with sickle cell trait have only one gene that affects hemoglobin, they usually have enough normal hemoglobin to prevent them from developing symptoms. Can physical activity affect hemoglobin levels When a person experiences intense physical stress — such as when they are in a high altitude location or when an untrained person works out with great intensity — some of their red blood cells may sickle. As a result, a person may develop a life threatening complication called rhabdomyolysis, which damages muscles, causing them to break down and release harmful substances into the blood. What causes abnormal hemoglobin levels in sickle cell anemia In sickle cell anemia, the hemoglobin protein is not normal. A genetic mutation within the HBB gene causes the hemoglobin to contain a chemical called valine instead of glutamic acid in protein chains that form hemoglobin. This damages red blood cells, causing them to sickle and die sooner than usual. The HBB gene is responsible for forming beta-globin chains, which are a component of hemoglobin. The premature death of red blood cells can mean that both hemoglobin and red blood cell levels are chronically low. So, in addition to having blood cells that stick together and carry oxygen less effectively, a person will not have enough red blood cells to effectively transport oxygen. Changes in hemoglobin structure Hemoglobin consists of four protein subunits: two subunits of alpha-globin and two of beta-globin. In people with SCD, certain mutations within the HBB gene can change the structure of the hemoglobin. Specifically, mutations code for an abnormal version of beta-globin, or HbS. This might occur in only one of the two beta-globin subunits. However, in sickle cell anemia, both beta-globin subunits of hemoglobin are replaced by abnormal HbS. This leads to the distortion of red blood cells and causes them to adopt a sickle shape. In other types of SCD, the hemoglobin subunits may be replaced with other abnormal hemoglobin types, such as HbC. These can also change the shape of the red blood cells. Types of SCD The type of SCD a person has will influence the symptoms they experience. The genes a person inherits determine the type of SCD they develop. The most common types of SCD are: Homozygous hemoglobin SS: The most common form of SCD, this variant means that a person inherits two copies of the “S” sickling gene — one from each parent. This is the most severe manifestation of SCD. Doctors call it sickle cell anemia.Hemoglobin sickle cell disease: People with this milder type of SCD inherit one “S” sickling gene and one “C” sickling gene, which is another type of abnormal hemoglobin gene. Hemoglobin sickle cell beta-thalassemia: This version of SCD means that a person gets one “S” sickling protein and one gene for beta-thalassemia, which is another type of abnormal hemoglobin. There are two subtypes: beta0-thalassemia, which is a more severe form, and beta+-thalassemia, which tends to be milder. Diagnosis People with access to medical care usually get a diagnosis as newborns. The routine newborn screening in the United States looks for signs of hemoglobin anomalies using a drop of blood. This screening can help medical professionals diagnose SCD. If a person did not have a newborn screening test or does not live in a country that provides this type of screening, they can undergo blood tests as an adult to detect SCD. Quantifying hemoglobin Some laboratory tests can separate the hemoglobin to look for the different variants and quantify them from blood samples. These tests include:Hemoglobin electrophoresis: This technique can identify the different hemoglobin types.High performance liquid chromatography: This technique also detects most hemoglobin types.Isoelectric focusing: This is a very sensitive method of detection. Treatment Although hematopoietic stem cell transplants show potential as a cure for SCD, they are not widely available. No cure is available to most people, which means that treatment mostly focuses on managing symptoms. A doctor may recommend lifestyle management strategies to prevent some complications associated with the condition. These strategies may include:drinking plenty of waterwashing one’s hands often to reduce the risk of infectionavoiding high altitudes Pain-relieving medication can help people with SCD manage episodes of pain, or pain crises. During a sickle cell crisis, a person may need to stay in the hospital. If their red blood cell and hemoglobin counts get very low, a person may need a blood transfusion. It is important for people with SCD to stay up to date with vaccinations and to practice safe food handling because they have a higher risk of serious complications if they contract an infection. Complications SCD can cause numerous complications and may shorten a person’s life, especially if they do not have access to adequate medical care. Possible complications include:dangerous blood clots throughout the bodyheart diseaseinfections strokepulmonary embolismkidney failureeye health issues, such as proliferative retinopathysplenic sequestration, which is a sudden and significant drop in hemoglobin bone damageaplastic crisis, which is a potentially life threatening emergency Summary In sickle cell anemia, a person’s hemoglobin levels are chronically low. This can cause several complications. However, the severity of complications varies from person to person and depends heavily on the type of SCD a person has. It is important for all people with SCD to get quality medical care, maintain a healthy lifestyle, and know the signs of an emergency so they can seek prompt care when necessary. Last medically reviewed on July 29, 2022Public HealthBlood / Hematologysickle cell disease 8 sourcescollapsedMedical News Today has strict sourcing guidelines and draws only from peer-reviewed studies, academic research institutions, and medical journals and associations. We avoid using tertiary references. We link primary sources — including studies, scientific references, and statistics — within each article and also list them in the resources section at the bottom of our articles. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.Ashorobi, D., et al. (2022). Sickle cell trait.https://www.ncbi.nlm.nih.gov/books/NBK537130Ballas, S. K., et al. (2021). Time to rethink haemoglobin threshold guidelines in sickle cell disease.https://onlinelibrary.wiley.com/doi/full/10.1111/bjh.17578Blood counts and sickle cell disease. (n.d.).https://www.stjude.org/treatment/patient-resources/caregiver-resources/patient-family-education-sheets/hematology/blood-counts-and-sickle-cell-disease.htmlFrömmel, C. (2018). Newborn screening for sickle cell disease and other hemoglobinopathies: A short review on classical laboratory methods-isoelectric focusing, HPLC, and capillary electrophoresis.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7548892/Sedrak, A., et al. (2021). Sickle cell disease.https://www.ncbi.nlm.nih.gov/books/NBK482384/Sickle cell disease. (2020).https://medlineplus.gov/genetics/condition/sickle-cell-disease/Sickle cell disease (SCD). (2022).https://www.cdc.gov/ncbddd/sicklecell/index.htmlVichinsky, E., et al. (2019). A phase 3 randomized trial of voxelotor in sickle cell disease.https://www.nejm.org/doi/full/10.1056/NEJMoa1903212FEEDBACK:Medically reviewed by Jenneh Rishe, RN — By Zawn Villines on July 29, 2022 Latest newsWhat sets 'SuperAgers' apart? Their unusually large neuronsOmega-3 may provide a brain boost for people in midlifeSeasonal affective disorder (SAD): How to beat it this fall and winterCDC: Monkeypox in the US 'unlikely to be eliminated in the near future'Why are more women prone to Alzheimer's? New clues arise Related CoverageSymptoms and treatment for sickle cell anemiaMedically reviewed by Emelia Arquilla, DO Sickle cell anemia is a genetic condition that causes red blood cells to malfunction. Learn about the causes, symptoms, and treatments.READ MORESickle cell disease: How racism affects care Many Black people have sickle cell disease, a chronic condition that can bring debilitating pain, yet systemic racism can often block their access to…READ MOREHow to manage sickle cell pain crisis Sickle cell pain crisis can have a sudden onset and cause extreme pain. Find out about home treatments, medications, and triggers here.READ MOREWhat are sickle cell blood cells? Sickle cells are stiff, inflexible red blood cells that can get stuck in blood vessels, leading to health complications. Learn how they differ from…READ MORESickle cells vs. healthy red blood cells: What to knowMedically reviewed by Angelica Balingit, MD How do sickle cells differ from healthy red blood cells? Learn why sickle cells are different, how this affects their function, and why it results in…READ MORE