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Hemoglobin F (HbF)

Published: July 27, 2026Updated: August 25, 2026

Hemoglobin F (HbF) is a type of hemoglobin normally found in fetuses and newborns, which is replaced by adult hemoglobin after birth. This biomarker measures the percentage of HbF in the total hemoglobin.

Quick summary

HbF measures the percentage of fetal hemoglobin in total hemoglobin.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
%
Clinical utility
diagnostic
Result kind
quantitative
FDA-cleared
Bio-Rad Hemoglobin F, Trinity CAPILLARYS
interpretation: {"text":"0–2% HbF in adults indicates a typical level post-development.","label":"Normal"}; {"text":"Levels above 2% may indicate hereditary persistence of fetal hemoglobin or other hematologic disorders.","label":"Elevated"}

Hemoglobin F (HbF) is a variant of hemoglobin that is the primary oxygen transport protein in the human fetus during the last seven months of development in the uterus and in newborns.

After birth, HbF is gradually replaced by adult hemoglobin (HbA), but some HbF may persist in adults, especially in certain blood disorders.

Measuring HbF levels is crucial in diagnosing conditions like thalassemia and sickle cell anemia, as well as monitoring the effectiveness of treatments for these disorders.

Frequently asked questions

What conditions can cause elevated HbF levels?
Elevated HbF levels can be caused by hereditary persistence of fetal hemoglobin, thalassemia, sickle cell anemia, and other hematologic disorders.
How is HbF measured?
HbF is typically measured through a blood test, often as part of a complete blood count (CBC) or a hemoglobin electrophoresis test.
  1. 1
    Mayo Clinic: Hemoglobinopathy TestingSource
  2. 2
    National Institutes of Health: Fetal HemoglobinSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy