Plasma molybdenum concentrations in children with and without phenylketonuria

Micronutrient levels and nutritional status of school children living in Northwest Ethiopia

Background

Several micronutrients are essential for adequate growth of children. However, little information is available on multiple micronutrient status of school children in Ethiopia. The present study was designed to evaluate the relationship between multiple micronutrient levels and nutritional status among school children.

Method

In this cross-sectional study, anthropometric data, blood and stool samples were collected from 100 children at Meseret Elementary School in Gondar town, Northwest Ethiopia. Serum concentration of magnesium, calcium, iron, copper, zinc, selenium and molybdenum were measured by inductively coupled plasma mass spectrometer. Anthropometric indices of weight-for-age, height-for-age and BMI-for-age were used to estimate the children's nutritional status. Stool samples were examined by standard microscopic methods for intestinal parasites.

Results

The prevalence of stunting, underweight, wasting and intestinal parasitoses among school children was 23%, 21%, 11% and18%, respectively. The mean serum levels of magnesium, calcium, iron, copper, zinc, selenium and molybdenum were 2.42±0.32 (mg/dl), 15.31±2.14 (mg/dl), 328.19±148.91 (μg/dl), 191.30±50.17 (μg/dl), 86.40±42.40 (μg/dl), 6.32±2.59 (μg/dl), and 0.23±0.15 (μg/dl), respectively. Selenium deficiency, zinc deficiency and magnesium deficiency occurred in 62%, 47%, and 2% of the school children, respectively. Height-for-age showed significant positive correlation with the levels of copper and molybdenum (p = 0.01) and with the levels of magnesium (p = 0.05).

Conclusion

Deficiencies of selenium and zinc were high among the school children although the deficiencies were not significantly related with their nutritional status. The prevalence of both malnutrition and intestinal parasitism was not negligible. These calls for the need to undertake multicentre studies in various parts of the country to substantiate the data obtained in the present study so that appropriate and beneficial strategies for micronutrient supplementation and interventions on nutritional deficiencies can be planned.

Molybdenum supplementation in phenylketonuria diets: adequate in early infancy?

BACKGROUND

Molybdenum concentrations in formulas exceed those in human milk by far. Infants with phenylketonuria require semisynthetic phenylalanine-restricted diets. Because these diets are presently supplemented with molybdenum, a study was conducted to determine whether retention and plasma concentration in the recipients are equivalent to those of healthy breast-fed infants.

METHODS

Balance and plasma studies were conducted in healthy breast-fed infants (n = 17) and in patients with phenylketonuria (n = 4) at the age of 4 weeks, and the plasma investigations were repeated at the ages of 4 and 12 months. The samples were analyzed by atomic absorption spectroscopy (balance studies) and high-resolution inductively coupled plasma mass spectrometry (plasma).

RESULTS

Molybdenum intake and retention in all infants with phenylketonuria were more than 18 times those of breast-fed infants. The plasma concentrations reflected these differences. A median of 0.04 microg/l was assessed in breast-fed infants at 4 weeks and less than 0.02 microg/l at 4 months of age. Comparative results of infants with phenylketonuria were 2.9 microg/l and 2.5 microg/l, respectively. There were no significant differences between the groups at 12 months of age.

CONCLUSIONS

The phenylketonuria diets investigated showed excessive retention and plasma concentrations of the essential trace element molybdenum in early infancy. In view of these findings, the present practice of molybdenum fortification should be revised.

Plasma micronutrient concentrations in infants undergoing therapy for phenylketonuria

Twenty-seven infants with classical phenylketonuria were evaluated longitudinally for 6 mo while ingesting Phenex-1 Amino Acid Modified Medical Food With Iron as their primary protein source. Intake of selected nutrients and biochemical indices of trace and ultratrace mineral status and plasma retinol and alpha-tocopherol concentrations were evaluated. The means of iron status indices (complete blood count, plasma ferritin, iron, transferrin saturation, total iron binding capacity) and the plasma concentrations of trace and ultratrace minerals (copper, manganese, molybdenum, selenium, zinc) and plasma retinol and alpha-tocopherol were in the reference ranges. Vitamin A intakes (r = 0.49, p < 0.05) and plasma retinol-binding protein concentrations (r = 0.42, p < 0.05) were positively correlated with plasma retinol concentrations at 3 mo of study. At 6 mo, concentrations of plasma transthyretin (r = 0.72, p < 0.01) and retinol-binding protein (r = 0.48, p < 0.05) were positively correlated with plasma retinol concentrations. At 6 mo, concentrations of plasma transthyretin (r = 0.52, p < 0.05) were positively correlated with retinol-binding protein concentrations. Phenex-1 supports normal mean iron status indices and mean concentrations of trace and ultratrace minerals, retinol, and alpha-tocopherol when fed in adequate amounts.