We recently published a trial named "Neutrophil-to-Lymphocyte Ratio (NLR) and Platelet-to-Lymphocyte Ratio (PLR) are Predictors of Heart Failure (HF)".1 In this study, we found that NLR can be used to predict mortality during the follow-up of HF patients. However, NLR and PLR were not sufficient to establish a diagnosis of HF. According to guidelines, HF diagnosis is generally made based on clinical signs and symptoms of patients. Other examinations and laboratory test are used to support or to rule out the HF diagnosis.2 Although NLR and PLR were higher in HF patients when compared to healthy controls, they are not sufficient, alone, to establish the diagnosis of HF. Use of n-terminal pro brain natriuretic peptide, a commonly used biomarker in congestive HF management, alone, is also not enough for diagnosis of HF, as the use of NLR alone.3 Another problem regarding the use of NLR and PLR in HF patients is the lack of specificity. NLR and PLR are ratios of different subgroups of blood cells. So, they should be affected in various disease situations. Neutrophil count may be increased in patients with a bacterial infection and platelets count may also be increased in patients with essential thrombocythemia. In our study, to minimize this problem, we excluded patients who had malignancies, connective tissue diseases, acute and chronic infections, renal disease and acute coronary syndromes.

As mentioned in the letter, NLR and PLR can be affected by metabolic syndrome. In our study population, we did not assess the presence of metabolic syndrome. However, there was no difference between the NLR and PLR values of patients with or without hypertension (HT), hyperlipidemia (HL) and diabetes mellitus (DM).4 In a previously reported study, NLR levels tended to be high in patients with HT and DM. Finally, another criticism is that "different automated hematological analyzers can also give different results of neutrophil, lymphocyte and platelet measurements". This is true, because different automated hematological analyzers use different techniques.5 But, considering the basic blood cell count, there was a good correlation between different automated hematological analyzers.6 And also, NLR and PLR are ratios of blood cells parameters, so they are not affected by the type of analyzers.

Caro Editor, o recente relatório sobre “Relações Neutrófilo- Linfócito (RNL), Plaqueta-Linfócito (RPL) e Insuficiência Cardíaca” é muito interessante.1 Durmus et al.1 relataram que a “RNL pode ser usada para prever a mortalidade durante o seguimento de pacientes com IC.” Realmente, o uso de um novo parâmetro para predizer insuficiência cardíaca é muito interessante. No entanto, como Durmus et al.1 mencionaram, tanto a RNL quanto a RPL “não foram suficientes para estabelecer um diagnóstico de HF.” Além disso, embora o presente relatório1 tenha sido bem concebido como um estudo de caso-controle pareado, o problema em relação à RNL e RPL deve ser discutido levando-se em conta a medicina laboratorial. Ambos os parâmetros são não-específicos. Vários fatores podem afetar os neutrófilos, linfócitos e plaquetas. Outras doenças concomitantes, tais como distúrbios imunológicos e malignidades podem alterar os valores de RNL e de RPL.2^-3 Além disso, a síndrome metabólica, que é comum entre os pacientes com doença cardíaca, também pode afetar os valores de RNL e RPL.4 Adicionalmente, o uso de diferentes analisadores hematológicos automatizados também pode resultar em diferentes medidas de neutrófilos, linfócitos e plaquetas.5