Table 3 Baseline characteristics of cases and controls Characteristic Recruited Age (years)* Hb (g/dl)* Male History of previous transfusion Wasted{ Stunted{ Malaria1 HIV" Bacteraemia** Cases 381 1.7 (1.1) (371) 3.6 (0.8) (381) 178/381 (46.7%) 57/378 (15.1%) 53/330 (16.1%) 176/331 (53.2%) 226/380 (59.5%) 45/357 (12.6%) 54/359 (15.0%) Controls 23 1.8 (0.9) (21) 9.9 (1.8) (23) 19/22 (86.4%) 0/23 (0%) 3/16 (18.8%) 7/17 (41.2%) 0/23 (0%) 0/9 (0%) 1/14 (7.1%) *Mean (SD) (total no). {Z-score ,22 weight-for-height. {Z-score ,22 height-for-age. 1Presence of Plasmodium falciparum asexual parasites in blood. "Positive for two rapid tests according to WHO guidelines. Discordant results and reactive results in children less than 18 month were resolved by PCR.19 **Presence of pathogenic bacteria using an automated BacT/Alert system (BioMerieux, Missouri, USA) and cultured for 5 and 56 days for routine pathogens and mycobacteria, respectively. RESULTS A total of 381 cases and 23 controls were recruited. Cases had an average age of 1.7 years (SD 1.1), and 46.7% (178/381) were male; controls had an average age of 1.8 years (SD 0.9) and 86.4% (19/22) were male. Death in-hospital occurred in 6.3% (24/381) of cases, with no deaths in controls (table 3). Of a total of 381 cases, 334 bone marrow aspirations were attempted, from which 303 marrow smears were prepared (fig 2). Forty-seven (12%) cases did not have a bone marrow aspiration for the following reasons: refusal by guardian, child Figure 2 Flow chart showing the number of children recruited and the number of bone marrow samples finally assessed using both Gale’s and intensive histological grading methods. Original article being too sick, unsuccessful aspiration. Twenty-two of 23 (96%) controls had a bone marrow aspirate collected and smear prepared. Therefore 303 case smears and 22 control smears were available for assessment. Gale’s grading method From the total smears considered for assessment, 66 of 303 (22%) cases and 4 of 22 (18%) controls were not assessed because they contained inadequate bone marrow fragments for proper assessment. Assessment of the remaining smears showed that iron deficiency was present among 33.8% (80/237) of cases and 61.1% (11/18) of controls. According to conventional grading, iron stores deficiency was more frequent among the controls than cases, but this difference was not significant (OR = 1.8, 95% CI 0.8 to 4.25). Intensive grading method Staining quality was adequate to enable assessment of macro- phage and erythroblast iron in 79% of cases (187/237) and 72% of controls (13/18). Cases and controls were classified into different iron status categories depending on iron assessment in fragment, macrophage and erythroblast as shown in table 4. Functional iron deficiency was the most common iron status category among both cases (39.6%; 74/187) and controls (46.2%; 6/13). Iron stores deficiency was less frequent among cases (21.9%; 41/187) than controls (38.5%; 5/13; p = 0.2). Categories of iron status classified by the intensive grading method were compared with values for peripheral blood markers of iron stores (fig 3). Low levels of ferritin and high levels of sTfR signify deficiency of iron stores in the absence of inflammation.20 21 Mean ferritin concentration was lower in J Clin Pathol 2009;62:685–689. doi:10.1136/jcp.2009.064451 687