[Correlation between level of metallic elements in urine and childhood acute leukemia]

To explore the relation between the level of metallic elements in urine and childhood acute leukemia.

A total of 71 patients under 15 years old who were newly diagnosed with acute leukemia between September 2007 and August 2008 without Downs' syndrome or other tumors, and 113 gender- and age-matched controls without tumors or congenital diseases were enrolled for the case-control study. The general data and potential risk factors were obtained by questionnaires. Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the metal concentrations in urine, which was collected randomly before chemotherapy. Logistic regression model was performed for univariate and multivariate analysis.

The questionnaire showed that there was significant difference in the proportion of children whose mothers had taken iron supplements during or 3 months before pregnancy between case group and control group, which was 28.2% (20/71) and 14.2% (16/113) respectively (Wald χ(2) = 5.438, P = 0.02). Univariate logistic regression analysis showed that levels of vanadium, manganese, iron, cobalt, copper, arsenic, and barium in urine from case group were all higher than those of control group with significant difference. The median values for vanadium in urine from case and control groups were 5.39 and 3.04 ng/mg creatinine (Wald χ(2) = 9.03, P < 0.05); the median values for manganese were respectively 4.46 and 2.44 ng/mg creatinine (Wald χ(2) = 10.57, P < 0.05); the median values for iron were separately 58.69 and 14.09 ng/mg creatinine (Wald χ(2) = 13.41, P < 0.05); the median values for cobalt were respectively 0.98 and 0.77 ng/mg creatinine (Wald χ(2) = 4.46, P < 0.05); the median values for copper were 61.17 and 10.90 ng/mg creatinine (Wald χ(2) = 8.15, P < 0.05); the median values for arsenic were respectively 55.93 and 36.11 ng/mg creatinine (Wald χ(2) = 4.57, P < 0.05); and the median values for barium were 8.55 and 2.87 ng/mg creatinine (Wald χ(2) = 4.82, P < 0.05). Multivariate logistic regression analysis showed that the level of iron in urine had a significantly positive relation with the incidence of childhood acute leukemia (OR = 1.009, 95%CI = 1.002 - 1.016).

The level of iron in urine might be related to the occurrence of childhood acute leukemia, but its specific role needs further investigation.