Zinc deficiency in Japanese children with idiopathic short stature

Assessment of Nutritional Status in the Diagnostic Evaluation of the Child with Growth Failure

Current clinical guidelines provide information about the diagnostic workup of children with growth failure. This mini-review focuses on the nutritional assessment, which has received relatively little attention in such guidelines. The past medical history, in particular a low birth size and early feeding problems, can provide information that can increase the likelihood of nutritional deficits or several genetic causes. The current medical history should include a dietary history and can thereby reveal a poorly planned or severely restricted diet, which can be associated with nutritional deficiencies. Children on a vegan diet should receive various nutritional supplements, but insufficient compliance has been reported in one-third of cases. While proper use of nutritional supplements in children consuming a vegan diet appears to be associated with normal growth and development, insufficient intake of supplements may impede growth and bone formation. Physical examination and analysis of height and weight over time can help differentiating between endocrine causes, gastrointestinal disorders, psychosocial problems, or underlying genetic conditions that prevent adequate nutritional intake. Laboratory screening should be part of the workup in every child with short stature, and further laboratory tests can be indicated if warranted by the dietary history, especially in children on a poorly planned vegan diet.

The Association Between Serum Zinc Levels and Anthropometric Measurements and Nutritional Indicators in Children With Idiopathic Short Stature

Background

Zinc (Zn) is an essential trace element, and its deficiency causes various symptoms, such as anemia, short stature, and poor weight gain, in children. Several studies have reported an association between Zn deficiency and short stature in children. However, few studies have reported on the relationship between serum Zn levels, body mass index (BMI), and nutritional indicators such as albumin, amino acids, and vitamin D.

Methods

We retrospectively analyzed the data of 56 children with idiopathic short stature. We investigated the mean serum Zn levels and the relationships among serum Zn levels and height standard deviation score (SDS), bodyweight SDS, BMI SDS, hemoglobin (Hb), albumin, alkaline phosphatase (ALP), insulin-like growth factor-1 (IGF-1), 25-hydroxyvitamin D (25(OH)D), and amino acid levels.

Results

The mean serum Zn levels of the study participants were 70.3±10 µg/dL. Serum Zn levels correlated significantly with weight SDS (r=0.472, p<0.001) and BMI SDS (r=0.416, p<0.001). In contrast, no significant association was found between serum Zn levels and height SDS (r=0.217, p=0.078). We found significant positive correlations between serum Zn levels and Hb and IGF-1 SDS (Hb: r=0.333, p=0.012; IGF-1 SDS: r=0.372, p=0.00478). Serum Zn levels were not correlated with albumin, ALP, 25(OH)D, and amino acid levels.

Conclusions

Serum Zn levels are associated with anthropometric measurements, especially body weight and BMI. It is important to evaluate Zn levels in children who fail to thrive, even in developed countries.

The associations between serum trace elements and bone mineral density in children under 3 years of age

We examined the associations of age and serum magnesium, iron, lead, copper, and zinc levels with bone mineral density (BMD) in 2412 children under 3 years of age in order to find a tool to monitor BMD in children without the use of expensive imaging techniques. One-way ANOVA and chi-square tests were used to determine the associations of age and serum trace elements with BMD. Multivariable logistic regression analysis was used to test the correlation of five serum trace elements with BMD after adjustments for potential confounding factors in children under 3 years of age. Significant associations between age and four serum trace elements and BMD were found. Compared to the group with the lowest serum levels detected, the adjusted odds ratio (OR) for the incidence of normal bone mineral density in the third magnesium concentration tertile, the third iron concentration tertile, the fifth copper concentration quintile, the third zinc concentration quintile, and the fifth zinc concentration quintile were 1.30 (95% confidence interval (CI) 1.02–1.67), 1.43 (95% CI 1.11–1.84), 1.42 (95% CI 1.04–1.94), 1.46 (95% CI 1.05–2.04), and 1.48 (95% CI 1.06–2.06), respectively. However, there was no significant correlation between serum lead level and BMD in this study. Age and serum magnesium, iron, copper, and zinc levels are positively associated with BMD in children under 3 years old.

Vitamin D Status in Children With Short Stature: Accurate Determination of Serum Vitamin D Components Using High-Performance Liquid Chromatography-Tandem Mass Spectrometry

OBJECTIVE

Vitamin D is critical for calcium and bone metabolism. Vitamin D insufficiency impairs skeletal mineralization and bone growth rate during childhood, thus affecting height and health. Vitamin D status in children with short stature is sparsely reported. The purpose of the current study was to investigate various vitamin D components by high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) to better explore vitamin D storage of short-stature children in vivo.

METHODS

Serum circulating levels of 25-hydroxyvitamin D2 [25(OH)D2], 25-hydroxyvitamin D3 [25(OH)D3], and 3-epi-25-hydroxyvitamin D3 [3-epi-25(OH)D3, C3-epi] were accurately computed using the LC-MS/MS method. Total 25(OH)D [t-25(OH)D] and ratios of 25(OH)D2/25(OH)D3 and C3-epi/25(OH)D3 were then respectively calculated. Free 25(OH)D [f-25(OH)D] was also measured.

RESULTS

25(OH)D3 and f-25(OH)D levels in short-stature subgroups 2 (school age: 7~12 years old) and 3 (adolescence: 13~18 years old) were significantly lower compared with those of healthy controls. By contrast, C3-epi levels and C3-epi/25(OH)D3 ratios in all the three short-stature subgroups were markedly higher than the corresponding healthy cases. Based on cutoff values developed by Endocrine Society Recommendation (but not suitable for methods 2 and 3), sufficient storage capacities of vitamin D in short-stature subgroups 1, 2, and 3 were 42.8%, 23.8%, and 9.0% as determined by Method 3 [25(OH)D2/3+25(OH)D3], which were lower than those of 57.1%, 28.6%, and 18.2% as determined by Method 1 [25(OH)D2+25(OH)D3+C3-epi] and 45.7%, 28.5%, and 13.6% as determined by Method 2 [25(OH)D2/3+25(OH)D3+C3-epi]. Levels of 25(OH)D2 were found to be weakly negatively correlated with those of 25(OH)D3, and higher 25(OH)D3 levels were positively correlated with higher levels of C3-epi in both short-stature and healthy control cohorts. Furthermore, f-25(OH)D levels were positively associated with 25(OH)D3 and C3-epi levels in children.

CONCLUSIONS

The current LC-MS/MS technique can not only separate 25(OH)D2 from 25(OH)D3 but also distinguish C3-epi from 25(OH)D3. Measurement of t-25(OH)D [25(OH)D2+25(OH)D3] alone may overestimate vitamin D storage in children, and short-stature children had lower vitamin D levels compared with healthy subjects. Ratios of C3-epi/25(OH)D3 and 25(OH)D2/25(OH)D3 might be alternative markers for vitamin D catabolism/storage in short-stature children. Further studies are needed to explore the relationships and physiological roles of various vitamin D metabolites.

Percentile values of serum zinc concentration and prevalence of its deficiency in Iranian children and adolescents: the CASPIAN-V study

Background To determine the prevalence of serum zinc deficiency and provide the age- and sex-specific percentile values of serum zinc in children and adolescents. Methods We used the gathered data through the CASPIAN-V study, a national survey conducted on 3500 students aged 7-18 years from 30 provinces of Iran. In this study, 1370 blood samples were selected randomly, and serum zinc concentration was measured using a Hitachi automated analyzer. Zinc deficiency was defined as a serum zinc level of less than 75 μg/dL. Age-sex specific reference percentile values were developed for serum zinc concentration. Results The mean age of participants was 12.4 ± 3.0 years; 49.3% were girls and 73% were urban inhabitants. Mean (standard deviation [SD]) of serum zinc concentration was 107.23 (25.81) μg/dL with a significant sex difference; 109.03 ± 26.12 μg/dL for males compared to 105.41 ± 25.3 μg/dL for females (p = 0.009). The prevalence of subclinical zinc deficiency was 4.9% (95% confidence intervals [CI]: 3.0, 6.9) in children and adolescents. Both zinc deficient and sufficient groups were similar in terms of age, sex and residential areas (all p-value > 0.05). Overall, the 5th and 95th percentile values for serum zinc were 68.28 and 151.87 μg/dL, respectively. The value of all percentiles consistently decreased with age. The 10-99th percentile values for serum zinc were greater in boys than girls at all ages. Conclusions Nearly 5% of subjects had zinc deficiency. Age-sex specific percentile values were established for Iranian children and adolescents.

Efficacy of zinc supplementation on growth and IGF-1 in prepubertal children with idiopathic short statures and low serum zinc levels

We investigated the effect of zinc supplementation on growth and serum IGF-1 levels in 10 prepubertal Japanese children with idiopathic short statures, who had serum zinc levels of less than 80 µg/dL. Subjects were started on oral zinc supplementation at a dose of 25 mg once daily. In three children, the doses were increased by 50 mg once daily during the study period of 12 mo. The serum zinc levels rose in all subjects and reached a normal range (beyond 80 µg/dL). However, it was found that zinc supplementation did not promote growth. Although the mean IGF-1 standard deviations significantly increased, the majority did not reach the normal range. There were no significant adverse events other than mild gastrointestinal symptoms in 4 out of 10 subjects during the supplementation period. The most likely reason why growth was not promoted is that the zinc supplementation dosage was not enough to stimulate IGF-1 generation and subsequent growth velocity.