Serum amyloid A protein levels as a possible aid in the diagnosis of acute appendicitis in children

Abstract

Hematological and biochemical tests, including white blood cell count (WBC), C-reactive protein (CRP) and other acute-phase reactants, have been used in the diagnosis of acute appendicitis. However, there is controversy among physicians about the value of this practice in children. The objective of our study was to evaluate serum amyloid A protein (SAA) levels in children with confirmed acute appendicitis and to compare the sensitivity and specificity of this marker of inflammation with those for WBC and CRP. A prospective cohort study of 60 children admitted with abdominal pain to rule out appendicitis was used in the study. Of these, 42 underwent surgery, while 18 children who had spontaneous amelioration within 24 h of admission were not operated on and served as controls. WBC and serum SAA and CRP levels were obtained preoperatively. Serum concentrations of the analytes were determined with particle-enhanced immunonephelometric methods. Patients with acute appendicitis had WBC, SAA and CRP levels higher than those of the control group (p<0.001). There was no appendicitis patient with a normal SAA value, while 21.4% of the patients had CRP values within the normal range. The performance of each test was measured by receiver-operating characteristic curves. Area under the curve (AUC) values were 0.849 for WBC, 0.868 for CRP and 0.964 for SAA. The sensitivity and specificity of these methods were 76% and 75% for WBC>10.0 x 10(9) /L, 62% and 94% for CRP>10 mg/L and 86% and 83% for SAA >45.0 mg/L, respectively. Circulating SAA levels have better discriminatory value than WBC or CRP in the assessment of acute appendicitis in children. Thus, this test appears to be of higher value than the current standards of care in the diagnosis of this condition.

Inflammatory markers for acute appendicitis in children: are they helpful?

“…Gronroos [4] reported that normal values of both WBCC and CRP were found in 7 of 100 consecutive children but in none of the 200 adults with pathologically confirmed acute appendicitis [7], and concluded that normal inflammatory markers can reliably exclude appendicitis in adults but not in children. Similarly, in a study by Lycopoulou et al [12] the sensitivity of elevated WBCC was 76%, and of elevated CRP only 62%, in 260 children with histologically confirmed appendicitis.…”

“…The rationale of laboratory tests in the diagnosis of acute appendicitis is based on the possibility of detecting signs of systemic inflammation with a diagnostic tool that is widely available and easy to perform, is minimally invasive, has limited costs, and can be repeated if necessary [14]. Although, over the last few decades, several markers of inflammation have been proposed to increase diagnostic accuracy in acute appendicitis (including phospholipase A 2 [15], serum amyloid A, [12], leukocyte elastase [16], neutrophil count [9], and several interleukins and cytokines [6]), WBCC and CRP are certainly the most widely used. They can also provide complementary information, with WBCC rising in the early phases of the inflammatory response and CRP increasing in advanced appendicitis [17].…”

“…The different cutoff values used for inflammatory markers may explain the different results observed in our study as compared with others. Our reference range for WBCC ( Table 1) is age dependent and based on values from an agematched reference population, whereas most pediatric studies use 10.0 Â 10 9 cells/L as the upper limit regardless of patient age [4,12]. In addition, we used 6.0 mg/L as the upper reference value for CRP as opposed to 10.0 as reported by others [12].…”

“…It has indeed been suggested that measuring both WBCC and CRP could avoid up to one quarter of negative appendectomies in adult patients [7]. However, only a few studies have been reported in pediatric patients [4,12], and the role of WBCC and CRP in excluding acute appendicitis in children has not been confirmed.…”

Evaluation of the Diagnostic Accuracy of Hepcidin and Conventional Biochemical Markers as Predictors in Disease Severity of Intra-Abdominal Inflammation

“…However, their specificity is low, because WBC or CRP levels tend to increase in all inflammatory diseases [1,2]. Several studies have explored the role of these biomarkers in improving the diagnosis of intra-abdominal inflammation in children and adults [3][4][5][6][7][8]. More accurate biomarkers are needed to reach the diagnosis for intra-abdominal inflammatory conditions.…”