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HbF

Hemoglobin electrophoresis Biomarker

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Collection Type: Blood

Body System

Related System: Hemoglobin electrophoresis

Overview

HbF (fetal hemoglobin) is the form of hemoglobin normally produced before birth (alpha2-gamma2). The HbF test measures the proportion of total hemoglobin made up by fetal hemoglobin, usually by hemoglobin electrophoresis or HPLC. It is used to detect disorders of hemoglobin switching and to evaluate unexplained anaemia, microcytosis, hemolysis, or abnormal newborn screening results. Elevated HbF in adults suggests genetic conditions such as hereditary persistence of fetal hemoglobin (HPFH), beta-thalassemia syndromes, or can reflect treatment effects (e.g., hydroxyurea in sickle cell disease). Values vary greatly with age (very high at birth, falling to adult levels by about 6–12 months) and show little sex-based difference.

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Test Preparation

No special preparation is required

Why Do I Need This Test

Profile: Hemoglobin electrophoresis (or HPLC) panel.
Symptoms: Chronic anaemia, jaundice, microcytic indices, recurrent pain crises, abnormal newborn screen.
Diagnoses/monitoring: Sickle cell disease, beta-thalassemia (trait/intermedia/major), HPFH, response to HbF‑inducing therapy.
Reasons for abnormal levels: Genetic mutations affecting globin switching, stress erythropoiesis, post‑transfusion, or drug therapy.
Biological meaning: Elevated HbF indicates persistence/reactivation of fetal hemoglobin production and can ameliorate severity of some hemoglobinopathies.
Lifestyle/factors: Certain medications (hydroxyurea), recent transfusion; little effect from diet or routine behaviors.
Family history: Known thalassemia or sickle cell disease signals need for testing.

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Understanding Test Results

Adults <1%: normal.
Values marginally above 1% (1–5%) are mild elevations may reflect hereditary persistence of HbF, beta‑thalassemia trait/heterozygosity, or recent marrow stress; interpret with CBC, iron studies and family history.
Moderate elevation (≈5–20%): suggests beta‑thalassemia intermedia, certain compound heterozygous hemoglobinopathies, or pharmacologic induction (partial response to hydroxyurea); clinical severity varies.
Marked elevation (>20%): consistent with beta‑thalassemia major, homozygous HPFH, or strong therapeutic induction; often associated with significant clinical and laboratory abnormalities and requires specialist evaluation.
Very high in neonates (60–90%): expected at birth; decline to infant/adult levels over months.
Low HbF is not clinically significant in adults.
Note: recent transfusion can dilute native HbF and mask true levels; elevated HbF often prompts genetic testing and hematology referral for definitive diagnosis and family studies.

Normal Range

Adults: <1% of total hemoglobin Newborn (at birth): 60–90% of total hemoglobin Infants (by ~6 months): <2% of total hemoglobin

FAQs

Q: What does HbF mean in blood?

A: HbF (fetal hemoglobin) is the form of hemoglobin normally present in the fetus and newborn. After birth it falls to low levels in healthy adults. Elevated HbF in blood can indicate hereditary persistence of fetal hemoglobin, certain hemoglobin disorders (like beta‑thalassemia or sickle cell disease), or marrow stress and recovery. Measuring HbF helps diagnose and monitor these conditions and assess treatment response.

Q: What does HbF mean?

A: HbF stands for fetal hemoglobin, the primary oxygen-carrying protein in fetuses. It has two alpha and two gamma globin chains and binds oxygen more tightly than adult hemoglobin (HbA). Levels normally fall after birth but may remain elevated in conditions like beta‑thalassemia, sickle cell disease, or hereditary persistence of fetal hemoglobin. Measuring HbF helps diagnose and monitor these disorders.

Q: What is the full form of HbF?

A: HbF stands for fetal hemoglobin (hemoglobin F), the primary oxygen-carrying protein in the fetus and newborn. Structurally it is α2γ2 (two alpha and two gamma globin chains), giving higher oxygen affinity than adult hemoglobin (HbA). HbF levels normally fall after birth but may remain elevated in certain hemoglobinopathies or with therapeutic agents that induce gamma‑globin production.

Q: What does HbF mean in hemoglobin?

A: HbF stands for fetal hemoglobin, the major oxygen-carrying protein in fetuses. It consists of two alpha and two gamma chains (α2γ2) and has higher oxygen affinity than adult hemoglobin, aiding placental oxygen transfer. HbF levels are high at birth and usually decline in infancy; persistently raised HbF can be seen in conditions like hereditary persistence of fetal hemoglobin, beta-thalassemia, and sickle cell disease.

Q: What causes high HbF?

A: High fetal hemoglobin (HbF) can be normal in newborns or caused by genetic conditions such as hereditary persistence of fetal hemoglobin and mutations affecting regulators (e.g., BCL11A, KLF1). It’s also elevated in hemoglobinopathies like beta‑thalassemia and sickle cell disease, during bone marrow stress or recovery, some myeloproliferative disorders, and after treatment with drugs such as hydroxyurea or chronic hypoxia.

Q: What is a normal HbF level in adults?

A: Normal fetal hemoglobin (HbF) in healthy adults is usually below about 1% of total hemoglobin; some laboratories accept up to 1–2%. Persistent elevations above this range warrant further evaluation for hereditary persistence of HbF, beta‑thalassemia, sickle cell disease, or other hemoglobin disorders. Measurement is typically by HPLC or hemoglobin electrophoresis interpreted with clinical context.