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Classificação de anemias em cães através de diferentes métodos analíticos
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Resumo(s)
RESUMO - A anemia, definida como a diminuição da contagem total de eritrócitos (RBC), mas
também do hematócrito (HT) e da concentração de hemoglobina (Hgb), é a alteração
hematológica mais comum encontrada na prática clínica veterinária, e pode ser a causa da
doença ou um marcador de doença subjacente. No que diz respeito ao mecanismo
fisiopatológico que lhe dá origem, estes são essencialmente de três tipos: perda (hemorragia),
destruição (hemólise) e diminuição da produção. As anemias podem ser classificadas com
base na resposta da medula óssea em regenerativas e não regenerativas.
O presente estudo teve como principal objetivo classificar anemias de uma forma mais
simples, prática e objetiva relacionando: o eritrograma, a avaliação da morfologia dos
eritrócitos no esfregaço sanguíneo, a contagem de reticulócitos (manual e automática) e por
fim do teste rápido de fragilidade osmótica (ROFT).
A amostra em estudo incluiu 35 cães com anemia, dos quais 54,3% (n=19) apresen taram uma anemia não regenerativa, e 45,7% (n=16) uma anemia regenerativa. Em relação
aos índices eritrocitários, metade dos cães (FR=50,0%) com anemia regenerativa e a maioria
(FR=84,2%) com anemia não regenerativa apresentaram uma anemia normocítica normocró mica. Nos cães com anemia regenerativa verificou-se que com o aumento da gravidade da
anemia existia um aumento da resposta reticulocitária, apesar de não se ter verificado uma
diferença estatisticamente significativa (p=0,6758). Observou-se uma maior ocorrência de
anisocitose quando a anemia era regenerativa do que nos casos de anemia não regenerativa
(pFisher=0,014). Relativamente à relação do RDW com a anisocitose, obteve-se uma ROC curve, que indicou um valor de RDW de 15,6%, com sensibilidade de 95% e especificidade
de 60%, muito diferente do cut-off facultado pelo analisador ProCyte Dx de 21,7%, com sen sibilidade 10% e especificidade de 100% o que prova que este último poderá levar a um sub diagnóstico de anisocitose. Não foi encontrada uma correlação entre a resposta regenerativa
da anemia e o ROFT (p=0,700), e apenas 22,9% dos cães em estudo tiveram um ROFT po sitivo, ainda que nenhum tivesse um diagnóstico de anemia hemolítica imuno-mediada. Ao
compararmos a contagem manual e automática absoluta de reticulócitos (CMaRet e CAaRet)
concluímos que os dois métodos se equivalem. E que, provavelmente, a CAaRet produz re sultados superiores ao da contagem manual.
Apesar dos exames laboratoriais automáticos serem mais rápidos, de evitarem erros
entre operadores, e oferecerem informações úteis para a determinação da causa da anemia,
é importante conhecermos as suas limitações, não devendo prescindir da observação e
avaliação do esfregaço de sangue.
ABSTRACT - Anaemia, defined as a decreased in total red blood cell (RBC) count, haematocrit (HT), or haemoglobin concentration (Hgb), is the most common hematologic abnormality encoun tered in veterinary clinical practice and can be the cause of disease or a marker of underlying disease. Regarding the pathophysiological mechanism that causes anaemia, these are essen tially of three types: loss, destruction, and decreased production of RBCs. Anaemias can be classified based on the bone marrow response into regenerative and non-regenerative. The aim of this study was to classify anaemias in a more simple, practical, and objective way, relating: the complete blood count, the evaluation of the erythrocyte morphology in the blood smear, the reticulocyte count (manual and automatic) and finally the rapid osmotic fra gility test (ROFT). The study included 35 dogs with anaemia, of which 54,3% (n=19) had non-regenerative anaemia, and 45,7% (n=16) had regenerative anaemia. Regarding the erythrocyte indices, half of the dogs (FR=50,0%) with regenerative anaemia and most of the dogs (FR=84,2%) with non-regenerative anaemia had normochromic normocytic anaemia. In dogs with regenerative anaemia, it was found that with an increase in the severity of anaemia, there was an increase in reticulocyte response, although there was not a statistically significant difference (p=0,6758). A greater occurrence of anisocytosis was observed when anaemia was regenerative than in cases of non-regenerative anaemia (pFisher=0,014). Regarding the relation between RDW and anisocytosis, a ROC-curve was obtained, which indicated an RDW value of 15,6%, with a sensitivity of 95% and specificity of 60%, very different from the cut-off provided by the ProCyte Dx haematology analyser of 21,7%, with sensitivity of 10% and specificity of 100%, which proves that the latter may lead to an underdiagnosis of anisocytosis. No correlation was found between the regenerative response of anaemia and the ROFT (p=0,700), and only 22,9% of the dogs under study had a positive ROFT, although none had a diagnosis of immune-medi ated haemolytic anaemia. When comparing the manual and automatic absolute reticulocyte count (MaRetC and AaRetC) we conclude that the two methods are equivalent. And probably, the AaRetC produces higher results than the manual count. Although automatic laboratory tests are faster, avoid inter-observer variation, and pro vide useful information for determining the cause of anaemia, it is important for clinicians to be aware of their limitations, and not neglect the observation and evaluation of the blood smear.
ABSTRACT - Anaemia, defined as a decreased in total red blood cell (RBC) count, haematocrit (HT), or haemoglobin concentration (Hgb), is the most common hematologic abnormality encoun tered in veterinary clinical practice and can be the cause of disease or a marker of underlying disease. Regarding the pathophysiological mechanism that causes anaemia, these are essen tially of three types: loss, destruction, and decreased production of RBCs. Anaemias can be classified based on the bone marrow response into regenerative and non-regenerative. The aim of this study was to classify anaemias in a more simple, practical, and objective way, relating: the complete blood count, the evaluation of the erythrocyte morphology in the blood smear, the reticulocyte count (manual and automatic) and finally the rapid osmotic fra gility test (ROFT). The study included 35 dogs with anaemia, of which 54,3% (n=19) had non-regenerative anaemia, and 45,7% (n=16) had regenerative anaemia. Regarding the erythrocyte indices, half of the dogs (FR=50,0%) with regenerative anaemia and most of the dogs (FR=84,2%) with non-regenerative anaemia had normochromic normocytic anaemia. In dogs with regenerative anaemia, it was found that with an increase in the severity of anaemia, there was an increase in reticulocyte response, although there was not a statistically significant difference (p=0,6758). A greater occurrence of anisocytosis was observed when anaemia was regenerative than in cases of non-regenerative anaemia (pFisher=0,014). Regarding the relation between RDW and anisocytosis, a ROC-curve was obtained, which indicated an RDW value of 15,6%, with a sensitivity of 95% and specificity of 60%, very different from the cut-off provided by the ProCyte Dx haematology analyser of 21,7%, with sensitivity of 10% and specificity of 100%, which proves that the latter may lead to an underdiagnosis of anisocytosis. No correlation was found between the regenerative response of anaemia and the ROFT (p=0,700), and only 22,9% of the dogs under study had a positive ROFT, although none had a diagnosis of immune-medi ated haemolytic anaemia. When comparing the manual and automatic absolute reticulocyte count (MaRetC and AaRetC) we conclude that the two methods are equivalent. And probably, the AaRetC produces higher results than the manual count. Although automatic laboratory tests are faster, avoid inter-observer variation, and pro vide useful information for determining the cause of anaemia, it is important for clinicians to be aware of their limitations, and not neglect the observation and evaluation of the blood smear.
Descrição
Dissertação de Mestrado Integrado em Medicina Veterinária
Palavras-chave
Anemia cão esfregaço de sangue hemograma contagem de reticulócitos teste rápido de fragilidade osmótica Anaemia dog blood smear complete blood count reticulocyte count rapid osmotic fragility test
Contexto Educativo
Citação
Forte MFRMP 2021. Classificação de anemias em cães através de diferentes métodos analíticos [dissertação de mestrado]. Lisboa: FMV-Universidade de Lisboa.
Editora
Universidade de Lisboa, Faculdade de Medicina Veterinária