ABSTRACT
La esferocitosis hereditaria es un grupo heterogéneo de desórdenes caracterizados por la variabilidad en la clínica, en los defectos proteicos del citoesqueleto eritrocitario y en el tipo de herencia. Se estudió la sensibilidad y especificidad de la concentración de hemoglobina corpuscular media (CHCM) y el índice de amplitud de distribución eritrocitaria (ADE) en el screening diagnóstico de la esferocitosis hereditaria. Noventa y cuatro pacientes fueron comparados con niños sanos de igual sexo y edad. Todos los índices se obtuvieron por impedancia eléctrica (autoanalizador hematológico Coulter JT). En los pacientes con esferocitosis hereditaria, la CHCM (35.67±1.33 g/dl) y el ADE (20.60±4.5%), fueron significativamente más elevados que en el grupo control (CHCM 33.48±0.68 g/dl, p 0.000; ADE 13.22±0.9%, p 0.000). Con los valores de corte utilizados en nuestro laboratorio (CHCM ≥ 34.5 g/dl; ADE ≥ 14.5%) ambos índices elevados mostraron una sensibilidad de 81% y una especificidad de 98.9% en el screening de esferocitosis hereditaria. La combinación de ambos índices es un excelente predictor para el diagnóstico de esferocitosis hereditaria.
Hereditary spherocytosis is a group of heterogenous disorders characterized by variability in its clinical manifestations, membrane protein defects and inheritance. We analysed the sensitivity and specificity of mean corpuscular hemoglobin concentration (MCHC) and red cell distribution width (RDW) in the diagnostic screening of hereditary spherocytosis. Ninetyfour patients were compared to equal number of healthy, age-matched children. All indexes were derived from measurements obtained by aperture impedance (Coulter Counter Model JT). In patients with hereditary spherocytosis, MCHC (35.67±1.33 g/dl) and RDW (20.60±4.5%) were significantly higher than in normal control subjects (MCHC 33.48±0.68 g/dl, p: 0.000; RDW 13.22±0.9%, p: 0.000). By using a cutoff for the MCHC of 34.5 g/dl and for the RDW of 14.5%, both indexes showed a sensitivity of 81% and a specificity of 98.9%. The combination of the two test is an excellent predictor for the diagnosis of hereditary spherocytosis.
Subject(s)
Child, Preschool , Female , Humans , Male , Erythrocyte Indices , Hemoglobins/analysis , Mass Screening/methods , Spherocytosis, Hereditary/blood , Confidence Intervals , Mass Screening/standards , Retrospective Studies , Sensitivity and Specificity , Spherocytosis, Hereditary/diagnosisABSTRACT
A interferência dos triglicerídeos plasmáticos sobre a determinação da hemoglobina foi observada em dosagens acima de 800 mg/dl, provavelmente devido ao aumento da turbidez. Este efeito espúrio leva a falsos resultados no cálculo da HCM e da CHCM. A substituição do plasma lipêmico por soluçäo salina corrige os resultados superestimados da hemoglobina, bem como permite obter resultados mais exatos no cálculo da HCM e da CHCM. (AU)
Plasma triglycerides interference on spectrophotometric hemoglobin determination wasobserved in blood samples with more than 800mg/dl, probably due to the turbidity increase. This spuriouseffect leads to false results in MCM and MCHC determination. Substituting saline solution for thelipaemic plasma corrects the overestimated hemoglobin determination as well as affording more accurateMCH and MCHC values. (AU)