biology

Hemolytic disease of the newborn

Hemolytic disease of the newborn is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Hemolytic disease of the newborn rather than just read about it. In short: Hemolytic disease of the newborn (HDN), hemolytic disease of the fetus and newborn (HDFN) or erythroblastosis fetalis, is an alloimmune condition that develops in a fetus at or around birth, when the IgG molecules (one of the five main types of antibodies) produced by the mother pass through the placenta. Among these antibodies are some which attack antigens on the red blood cells in the fetal circulation, breaking…

Key takeaways

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Reproduce the core statement of Hemolytic disease of the newborn from memory before moving on to harder problems.

Reference excerpt

Hemolytic disease of the newborn (HDN), hemolytic disease of the fetus and newborn (HDFN) or erythroblastosis fetalis, is an alloimmune condition that develops in a fetus at or around birth, when the IgG molecules (one of the five main types of antibodies) produced by the mother pass through the placenta. Among these antibodies are some which attack antigens on the red blood cells in the fetal circulation, breaking down and destroying the cells. The fetus can develop reticulocytosis and anemia. The intensity of this fetal disease ranges from mild to very severe, and fetal death from heart failure (hydrops fetalis) can occur. When the disease is moderate or severe, many erythroblasts (immature red blood cells) are present in the fetal blood, earning these forms of the disease the name erythroblastosis fetalis (British English: erythroblastosis foetalis). HDFN represents a breach of immune privilege for the fetus or some other form of impairment of the immune tolerance in pregnancy. Various types of HDFN are classified by which alloantigen provokes the response. The types include ABO, anti-RhD, anti-RhE, anti-Rhc, anti-Rhe, anti-RhC, multiantigen combinations, and anti-Kell. Although global prevalence studies of the differential contribution of those types are lacking, regional population studies have shown the anti-RhD type to be the most common cause of HDFN, followed by anti-RhE, anti-RhC, and anti-Rhc.

Signs and symptoms

Signs of hemolytic disease of the newborn include a positive direct Coombs test (also called direct agglutination test), elevated cord bilirubin levels, and hemolytic anemia. It is possible for a newborn with this disease to have neutropenia and neonatal alloimmune thrombocytopenia as well. Hemolysis leads to elevated bilirubin levels. After delivery, bilirubin is no longer cleared (via the placenta) from the neonate's blood and the symptoms of jaundice (yellowish skin and yellow discoloration of the whites of the eyes, or icterus) increase within 24 hours after birth. Like other forms of severe neonatal jaundice, there is the possibility of the neonate developing acute or chronic kernicterus, however the risk of kernicterus in HDN is higher because of the rapid and massive destruction of blood cells. Isoimmunization is a risk factor for neurotoxicity and lowers the level at which kernicterus can occur. Untreated profound anemia can cause high-output heart failure, with pallor, enlarged liver and/or spleen, generalized swelling, and respiratory distress. HDN can be the cause of hydrops fetalis, an often-severe form of prenatal heart failure that causes fetal edema.

Complications Complications of HDN could include kernicterus, hepatosplenomegaly, inspissated (thickened or dried) bile syndrome and/or greenish staining of the teeth, hemolytic anemia and damage to the liver due to excess bilirubin. Conditions that may cause similar symptoms in the newborn period include: acquired hemolytic anemia, congenital toxoplasma, congenital syphilis infection, congenital obstruction of the bile duct, and cytomegalovirus (CMV) infection.

High at birth or rapidly rising bilirubin Prolonged hyperbilirubinemia Bilirubin Induced Neurological Dysfunction Cerebral Palsy Kernicterus Neutropenia Thrombocytopenia Hemolytic anemia – must not be treated with iron Late onset anemia – must not be treated with iron. Can persist up to 12 weeks after birth.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Hemolytic disease of the newborn

Start with the simplest possible case. Write down what Hemolytic disease of the newborn claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Hemolytic disease of the newborn before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Hemolytic disease of the newborn ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Hemolytic disease of the newborn

In research: Hemolytic disease of the newborn appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Hemolytic disease of the newborn in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Hemolytic disease of the newborn is common in secondary-school and first-year university syllabi. It links to neighbouring topics Acquired hemolytic anemia, Disorders originating in the perinatal period, Haemorrhagic and haematological disorders of fetus and newborn, so understanding it makes those chapters shorter.
In everyday life: Look for Hemolytic disease of the newborn outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Hemolytic disease of the newborn in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Hemolytic disease of the newborn means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Hemolytic disease of the newborn out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Hemolytic disease of the newborn in simple terms?

Why does Hemolytic disease of the newborn matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Hemolytic disease of the newborn?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Hemolytic disease of the newborn.