J Korean Med Sci.  2017 Dec;32(12):2051-2057. 10.3346/jkms.2017.32.12.2051.

Urine Methyl Hippuric Acid Levels in Acute Pesticide Poisoning: Estimation of Ingested Xylene Volume and Association with Clinical Outcome Parameters

• Choi CY
• Cho N
• Park SY
• Park S
• Gil HW
• Hong SY

• KMID: 2396385
• DOI: http://doi.org/10.3346/jkms.2017.32.12.2051

Abstract

To determine the relationship between the oral ingestion volume of xylene and methyl hippuric acid (MHA) in urine, we measured MHA in 11 patients whose ingested xylene volume was identified. The best-fit equation between urine MHA and ingested amount of xylene was as follows: y (ingested amount of xylene, mL/kg) = −0.052x² + 0.756x (x = MHA in urine in g/g creatinine). From this equation, we estimated the ingested xylene volume in 194 patients who had ingested pesticide of which the formulation was not available. Our results demonstrated that oxadiazole, dinitroaniline, chloroacetamide, organophosphate, and pyrethroid were xylene-containing pesticide classes, while the paraquat, glyphosate, glufosinate, synthetic auxin, fungicide, neonicotinoid, and carbamate classes were xylene-free pesticides. Sub-group univariate analysis showed a significant association between MHA levels in urine and ventilator necessity in the pyrethroid group. However, this association was not observed in the organophosphate group. Our results suggest that MHA in urine is a surrogate marker for xylene ingestion, and high urine MHA levels may be a risk factor for poor clinical outcome with some pesticide poisoning.

Keyword

Pesticide; Xylene; Methyl Hippuric Acid; Respiratory Failure; Acute Pesticide Poisoning

MeSH Terms

Biomarkers
Eating
Humans
Indoleacetic Acids
Paraquat
Pesticides
Poisoning*
Respiratory Insufficiency
Risk Factors
Ventilators, Mechanical
Xylenes*
Biomarkers
Indoleacetic Acids
Paraquat
Pesticides
Xylenes

Figure

• 

  Fig. 1 Correlation between urine MHA level and ingested amount of xylene in 11 cases. The best fit equation between urine MHA and ingested amount of xylene was; y (ingested amount of xylene, mL/kg = −0.052x2 + 0.756x (x = MHA in urine in g/g creatinine). MHA = methyl hippuric acid.

• 

  Fig. 2 The accuracy between the TV and PV of the ingested xylene volume. (A) Scatter plot of TV and PV for ingested xylene amount. (B) Bland-Altman plot. Horizontal lines are drawn at the mean difference, and at the limits of agreement, which are defined as the mean difference ± 2 times the SD of the differences. Note that all data are within 2 SDs of the mean value. TV = true value, PV = predictive value, SD = standard deviation, CCC = concordance correlation coefficient, CI = confidence interval.

• 

  Fig. 3 Estimated ingested volume of xylene according to pesticide class. The pesticide classes in which the ingested xylene volume was greater than the upper limit of the base line (i.e., 0.01 g/g creatinine) in more than one patient were chloroacetamide (n = 6), dinitroaniline (n = 2), organophosphate (n = 24), oxadiazole (n = 1), and pyrethroid (n = 14).

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