Howell-Jolly body counting has long been considered a potential tool for assessing splenic function. However, a recent study published in the Clinical & Laboratory Haematology journal by G.R. Corazza et al. in 1990 challenges the reliability of this technique. This article reevaluates their findings and explores the implications of Howell-Jolly body counting in evaluating splenic function.
What is Howell-Jolly Body Counting?
Howell-Jolly bodies are small, spherical remnants of the nucleus that remain within circulating red blood cells (RBCs) after they are normally expelled by the spleen. They are considered the most characteristic peripheral blood abnormality observed after splenectomy, the surgical removal of the spleen.
Howell-Jolly body counting involves visually examining blood samples under a microscope and quantifying the number of these nuclear remnants present in a certain number of RBCs. Traditionally, staining techniques such as the May-Grünwald/Giemsa method and the Feulgen reaction have been used to enhance the visibility of Howell-Jolly bodies.
Is Howell-Jolly Body Counting a Reliable Measure of Splenic Function?
The reliability of Howell-Jolly body counting as an indicator of splenic function has been a matter of debate in the medical community. Corazza et al.’s research questions the accuracy of this technique and presents a reassessment of its validity.
The authors compared Howell-Jolly body counting, using both the May-Grünwald/Giemsa method and the Feulgen reaction, with pitted cell counting, a technique considered more reliable for assessing splenic hypofunction. Pitted cell counting involves quantifying the number of RBCs with a concave deformity caused by splenic removal.
In their study, Corazza et al. found a significant correlation (P < 0.0001) between Howell-Jolly body counts stained by either technique and pitted cell counts. This suggests that Howell-Jolly body counting, while perhaps less sensitive compared to pitted cell counting, can still serve as a simple and reliable method for identifying cases with a real risk of overwhelming infections.
What are the Limitations of Howell-Jolly Body Counting as an Assessment Technique?
Despite its potential role in assessing splenic function, Howell-Jolly body counting has several limitations to consider. Firstly, Howell-Jolly bodies are not exclusive to splenic dysfunction. Conditions such as megaloblastic anemia and other abnormalities of erythroid maturation can also lead to the appearance of Howell-Jolly bodies.
Additionally, Howell-Jolly body counting is subjective and dependent on the observer’s expertise in identifying these nuclear remnants. Interobserver variability may influence the accuracy and reproducibility of the results. Moreover, the staining techniques used can vary between laboratories, potentially affecting the consistency of results.
Furthermore, Howell-Jolly bodies are not always observed in cases of mild splenic hypofunction. Corazza et al.’s study found that Howell-Jolly bodies were not detectable when pitted cell counts fell between 4 and 8%, indicating a very mild degree of splenic hypofunction. However, for pitted cell counts above 8%, there was a consistent increase in Howell-Jolly body counts.
How Does Howell-Jolly Body Counting Compare to Pitted Cell Counting for Evaluating Splenic Hypofunction?
Pitted cell counting is generally considered a more sensitive method for evaluating splenic hypofunction compared to Howell-Jolly body counting. Howell-Jolly bodies may only become detectable when pitted cell counts indicate a moderate to severe level of dysfunction.
However, Howell-Jolly body counting still holds value as a non-invasive, simple, and widely available technique for identifying cases at risk of overwhelming infections. Pitted cell counting requires specialized equipment and expertise, making it less accessible in non-specialized medical institutions.
Are Howell-Jolly Bodies Always Detectable When Pitted Cell Counts Are Consistent with Mild Splenic Hypofunction?
No, Howell-Jolly bodies are not always detectable when pitted cell counts indicate mild splenic hypofunction. Corazza et al.’s study revealed that Howell-Jolly bodies were not observed when pitted cell counts fell between 4 and 8%, representing a very mild level of splenic dysfunction.
Although Howell-Jolly bodies may not be present in these cases, it is important to monitor pitted cell counts as they can serve as an early indicator of splenic hypofunction. Regular follow-up and ongoing assessment are crucial to identify any deterioration in splenic function and the associated risk of infections.
In summary, Howell-Jolly body counting, despite its limitations, remains a valuable tool for identifying and monitoring cases associated with a real risk of overwhelming infections. While pitted cell counting is more sensitive, it requires specialized equipment and expertise. Hence, Howell-Jolly body counting serves as a pragmatic and accessible method for assessing splenic function in non-specialized medical institutions.
“Howell-Jolly body counting may still be regarded as a simple and reliable technique for identifying and monitoring those cases associated with a real risk of overwhelming infections.” – G.R. Corazza et al.
For more details, refer to the full research article: Howell-Jolly body counting as a measure of splenic function. A reassessment – CORAZZA – 1990