Non-anaemic iron deficiency identified by ZPP test in extremely premature infants: prevalence, dietary risk factors, and association with neurodevelopmental problems

INTRODUCTION

The aims of this study were to determine, in a cohort of extremely premature infants, the prevalence of iron deficiency identified by zinc protoporphyrin/heme ratio (ZPP) testing, and its association with neurodevelopmental problems and dietary risk factors for iron deficiency.

METHODS

Infants of less than 29 weeks' gestation or less than 1000 g birth weight were studied prospectively at a multidisciplinary follow-up clinic. Assessments were made at a corrected age of either 12 months (n=72) or 2 years (n=69). Physical examination, Griffiths Developmental Scale, and neurosensory-motor assessment were administered, information on diet and behaviour was obtained by questionnaire, and a fingerprick ZPP ratio was performed to identify iron deficiency.

RESULTS

18.4% of infants had positive ZPP tests. There was no significant association between a positive ZPP test result and dietary risk factors, or symptoms of lethargy, irritability or poor attention. In children without cerebral palsy, there was no difference on Griffiths scores or neurosensory-motor assessment between ZPP-positive and ZPP-negative groups. The diagnosis of cerebral palsy (n=12) was significantly associated with both a positive ZPP test and a lower Griffiths general quotient (GQ) score.

CONCLUSIONS

Iron deficiency occurs commonly in extremely low birth weight (ELBW) children in early childhood, and is not predicted by dietary risk factors. The prevalence of iron deficiency is increased in ELBW children with cerebral palsy. Non-anaemic iron deficiency (NAID) does not impair development or significantly affect behaviour of ELBW subjects who do not have cerebral palsy.

High levels of nitric oxide synthase activity are associated with nasal polyp tissue from aspirin-sensitive asthmatics

The pathogenesis of aspirin intolerance remains unclear. Inducible nitric oxide synthase (iNOS) expression is upregulated in nasal polyp epithelium, implying a role for nitric oxide (NO) in its formation. We decided to compare iNOS activity in polyp tissue from patients with and without aspirin intolerance. Nasal polyp tissue was collected from 15 patients undergoing routine nasal polypectomy. These patients were classified into three groups: Group A comprised patients with nasal polyps without asthma; Group B contained patients with nasal polyps and asthma; and Group C comprised patients with nasal polyps, asthma and aspirin sensitivity. All subjects in Group C had a history of aspirin-induced reaction and a confirmatory intranasal challenge with lysine-aspirin. NOS activity was measured by the ability of tissue homogenates to convert 3,4-L-arginine to L-citrulline in an L-N(G)-nitro-L-arginine-inhibitable fashion. The iNOS activity (picomoles) in polyp tissue from the 3 groups was: A, 248.72+/-220.79; B, 23.71+/-41.06; and C, 549.71+/-132.11. Thus, nasal polyps from patients with Samter's triad had a significantly higher iNOS activity (p = 0.004; one-way ANOVA). This finding does not correlate simply with disease severity or with the occurrence of asthma and could indicate another important facet of aspirin-induced airways disease.