New cut-off values for ferritin and soluble transferrin receptor for the assessment of iron deficiency in children in a high infection pressure area

Background:

Due to the potential risk of iron supplementation in iron replete children, it is important to properly identify children who may require iron supplementation. However, assessment of the iron status has proven to be difficult, especially in children living in areas with high infection pressure (including malaria).

Aims and Methods:

Biochemical iron markers were compared to bone marrow iron findings in 381 Malawian children with severe anaemia.

Results:

Soluble transferrin receptor/log ferritin (TfR-F index), using a cut-off of 5.6, best predicted bone marrow iron stores deficiency (sensitivity 74%, specificity 73%, accuracy 73%). In order to improve the diagnostic accuracy of ferritin or sTfR as a stand-alone marker, the normal cut-off value needed to be increased by 810% and 83% respectively. Mean cell haemoglobin concentration (MCHC), using a cut-off of 32.1 g/dl, had a sensitivity of 67% and specificity of 64% for detecting iron stores deficiency.

Conclusion:

TfR-F index incorporated the high sensitivity of sTfR, a proxy for cellular iron need, and the high specificity of ferritin, a proxy for iron stores. In areas with a high infection pressure, the TfR-F index best predicted iron deficiency. However, in settings where diagnostic tests are limited, MCHC may be an acceptable alternative screening test.

Bloody diarrhoea of adults in Malawi: clinical features, infectious agents, and antimicrobial sensitivities

In a prospective study, 132 hospital out-patients presenting with bloody diarrhoea ('cases') were evaluated in Malawi, Central Africa; 73 out-patient tuberculosis suspects acted as controls. Most (100/132, 76%) subjects reported an illness lasting < or = 5 d with > 5 bowel actions in the preceding 12 h; 39/132 (30%) reported use of systemic antimicrobial drugs in the preceding week; 57% (74/130) had a body mass index < 20; 4% (5/131) were febrile; and 18/130 (13%) had one or more sign(s) of dehydration. The 73 controls reported no diarrhoea and more systemic antimicrobial drug use (P = 0.0003), but were otherwise comparable to the subjects. All stool samples from controls and 38/124 (31%) from cases were macroscopically normal. Only 32% (40/124) of the cases had blood visible in the stool. Parasitic gut infections were found in 42/124 (34%) cases compared with 1/60 (2%) controls (P < 0.0001). The commonest parasite was Schistosoma mansoni. Bacterial cultures were positive in 32/124 (26%) of the subjects. Shigella dysenteriae (Sd) 1 accounted for 53% (17/32) of these. All bacterial isolates were sensitive in vitro to nalidixic acid and ciprofloxacin, while only 18% were sensitive to cotrimoxazole. Sd 1 with significant antimicrobial resistance continues to cause seasonal epidemics of dysentery in Malawi. During these, approximately two-thirds of patients presenting with bloody diarrhoea have no blood visible in the stool. Nalidixic acid remains the drug of choice but its use should be restricted to patients at greatest risk of complicated shigellosis.