Fetal Hemoglobin, Quantitative

The metalloprotein molecule, called Hemoglobin (Hb), is a significant part of the human blood circulatory system. It is present in the red blood cells or erythrocytes, and carries oxygen, giving blood its red color. There are many types of hemoglobin, like HbA, HbA2, HbS, HbH, HbM, HbF, etc. Fetal hemoglobin, also known as Hemoglobin F or HbF, is the major hemoglobin developed in the body during gestation. It helps in oxygen transfer from the mother's bloodstream to the fetus.

During adulthood, the production of Fetal Hb stops, and adult-type hemoglobin production begins. HbF is still present in healthy human adults, although in a small quantity. However, hereditary persistence of fetal hemoglobin (HPFH) occurs if abnormal amounts of HbF are present in adults. Various hereditary diseases occur to this abnormality, such as:

• Heterozygous beta thalassemia minor (HBT)
• Sickle cell diseases 
• Hereditary spherocytosis
• Fanconi anemia
• Hemolytic anemia
• Hypoplastic anemia
• Megaloblastic anemia
• Pernicious anemia
• Acquired aplastic anemia
• Myelophthisic anemia 
• All types of leukemia, like erythroleukemia, juvenile chronic myelogenous leukemia, etc. 
• Multiple myeloma and lymphomas 
• Bone marrow metastasis

It is possible to diagnose such inherited disorders that impact hemoglobin production via the Fetal Hemoglobin Quantitative Test. Known also as Hgb electrophoresis, this is a part of the routine screening tests during pregnancy. This test is most effective in determining the fetal hemoglobin level in infants. Even adults and children can get their HbF levels measured through this test. Some of the common symptoms that occur due to HbF abnormality include:

• Weakness
• Fatigue 
• Stunted growth
• Irregular heartbeat
• Dark urine 
• Pale/yellow skin 
• Deformed facial bone structure 
• Bloody stools or Melena neonatorum

Sometimes, it is also possible that the patients will not show any visible symptoms but can transfer the gene to their fetus. This can only be determined by Hgb electrophoresis tests or hemoglobinopathy. Your doctor may prescribe the Fetal Hemoglobin Quantitative Test if they detect any such symptoms. It is also done to rule out the possibility of thalassemia occurring in the baby during pregnancies.

The hematology test of Fetal Hb includes the alkali denaturation test or Apt test. It helps distinguish between the neonatal or fetal blood and the maternal blood present in the stool or vomit of the newborn. It also differentiates the blood of the newborn from the vaginal blood of the mother.

The Kleinauer-betke medical test also confirms the amount of hemoglobin transferred to the mother's bloodstream from the fetus. Since red blood cells with higher fetal Hb are acid-resistant, the alkali denaturation test can identify them. The Capillary electrophoresis method is most helpful for conducting this test.

The blood sample is collected using a standard venipuncture method. In infants, the pricking is done at the heel. Apollo 24|7 offers the Fetal Hemoglobin Quantitative Test.

Based on the results, your doctor can prescribe various treatments. For splenectomized β-thalassemia patients, a low dose of aspirin may be recommended. However, for Hereditary persistence of fetal hemoglobin diseases, like β-thalassemia, sickle cell anemia, etc., allogeneic hematopoietic stem cell transplantation (HSCT) is the only cure. 
 

Medically reviewed by Dr. Jaya Prakash Pani, Obstetrics and Gynaecology, Apollo Hospitals Old Sainik School Road, Bhubaneswar

Frequently asked questions

What does a positive Fetal Hemoglobin Test mean?

Positive Fetal Hemoglobin Quantitative Test results confirm the presence of blood disorders like myeloid leukemia, thalassemia, and sickle cell anemia. It also determines if the maternal blood is transferred into the blood of the fetus or newborn. The test detects the Hereditary persistence of fetal hemoglobin.

What is the ideal count of HbF?

The human fetus has the highest percentage of HbF, which reduces as it enters adulthood. In a regular human body, the level of HbF is about 0.8% - 2%, and in some cases, as low as 0.6%. On average, 0.3%-4.4% of fetal hemoglobin cells have been noticed among normal adults.

What is the reason behind the increased level of HbF?

Higher levels of HbF can occur due to blood disorders or Hereditary persistence of fetal hemoglobin diseases. During six weeks of pregnancy, the production of HbF cells starts. Usually, the HbF level is the highest in the fetus stage during gestation. However, six months after birth, it usually drops in a regular healthy child.

How is fetal hemoglobin tested?

The alkali denaturation or APT test method helps determine the level of fetal hemoglobin. It also confirms the origin of the blood found in a stool sample or Emesis sample from a pregnant mother or a newborn. Finding out whether the blood came from the mother or occurred due to GI hemorrhage can help doctors prescribe the necessary treatment.

Is there a cure for fetal anemia?

For moderate to severe anemia cases in neonates, blood transfusion can help while the baby is still in the womb. A sampling of the fetal blood and transfusion method is used for treatment. Compatible red blood cells are then transfused via the umbilical vein with the help of ultrasound visualization.

Is fetal anemia fatal?

If left untreated, fetal anemia can be fatal for the fetus. It happens mainly because of isoimmunization, i.e., incompatibility between the fetus and mother’s blood types. Another circumstance is hydrops fetalis, where a fluid buildup occurs in the tissues and organs of the baby, causing it to swell.