A nurse is caring for an infant who is admitted to the hospital with a diagnosis of haemolytic disease. The nurse reviews the laboratory results, expecting to note which of the following in this infant?

1. A

   Decreased bilirubin count

2. B

   Elevated blood glucose level

3. C

   Decreased RBC count

4. D

   Decreased white blood cell count

Appeared in: DHS 2018 shift 1st

Explanation

• Haemolytic disease of the newborn (HDN) is a condition where maternal antibodies cross the placenta and attack the infant's red blood cells (RBCs).
• This immune-mediated destruction of RBCs is called hemolysis.
• The direct and primary consequence of hemolysis is a reduction in the total number of circulating red blood cells, leading to a decreased RBC count and anemia.

Why Other Options Were Wrong

• Option A: This is the opposite of what occurs. Bilirubin is a waste product from the breakdown of heme in red blood cells. Increased hemolysis leads to a rapid rise in bilirubin levels (hyperbilirubinemia), which causes jaundice.
• Option B: Haemolytic disease does not directly cause hyperglycemia. In severe cases, infants may experience stress that can affect glucose, but more characteristically, some infants with severe HDN can develop hyperinsulinism and subsequent hypoglycemia (low blood sugar).
• Option D: The pathological process in HDN is specific to red blood cells. Maternal antibodies target antigens on the RBC surface, not on white blood cells (leukocytes). Therefore, the WBC count is not expected to decrease.

Related Visual

Clinical Relevance

• Nursing practice connection: Use the key finding related to Laboratory findings in Haemolytic Disease of the Newborn (HDN) to guide bedside assessment, documentation, and the next nursing action.
• Nurses play a vital role in monitoring infants with suspected or confirmed HDN for key signs of anemia (pallor, tachycardia, poor feeding) and jaundice.
• Prompt and accurate interpretation of laboratory results, including RBC count, bilirubin levels, and hemoglobin, is essential for guiding timely interventions such as phototherapy or exchange transfusions to prevent complications like kernicterus.
• What if? If the infant's lab results showed a normal RBC count but a significantly elevated direct (conjugated) bilirubin level, the focus of investigation would shift from hemolysis to causes of cholestasis, such as biliary atresia or neonatal hepatitis.

How to Approach the Question

• First, identify the core pathophysiology described in the question: 'haemolytic disease'.
• Break down the term: 'Hemo' refers to blood, and 'lytic' refers to destruction. Therefore, the disease involves the destruction of blood cells.
• Recall or deduce which blood cells are affected in this specific neonatal disease. Haemolytic disease of the newborn specifically involves the destruction of red blood cells.
• Predict the most direct laboratory finding resulting from the destruction of red blood cells. A loss of RBCs will lead to a 'decreased RBC count'.
• Evaluate the given options. 'Decreased RBC count' directly matches the prediction.
• Eliminate other options by considering the secondary effects. RBC breakdown releases bilirubin, so bilirubin would be elevated, not decreased. The process does not primarily involve glucose or white blood cells.

Concept Tested & Keywords

• Concept Tested: Laboratory findings in Haemolytic Disease of the Newborn (HDN)
• Stem keywords: infant, haemolytic disease, laboratory results
• Lead-in keywords: expecting to note
• Clinical cues: Age/sex group narrows the expected diagnosis, intervention, or normal reference range.
• Negative lead-in flag: false

Question ID

QPAzNWPZaHzHi3kVCVezw8

Copy ID

Reference Book

E6 Nelson Textbook of Pediatrics(2024) — Volume 1 pp. 1135-1137, 1117-1119