Is there "seasonal" variation in height velocity in children treated with growth hormone? Data from the National Cooperative Growth Study

Regional Differences in Height, Weight, and Body Composition may Result from Photoperiodic Responses: An Ecological Analysis of Japanese Children and Adolescents

This ecological study examined whether geographical differences in the physique of Japanese children and adolescents can be explained from the perspective of photoperiodicity induced by effective day length (light duration exceeding a certain threshold of illuminance) using prefecture-level anatomical data and Mesh Climatic Data. Multiple regression analysis for height prediction demonstrated that when controlled by weight, effective day lengths of the longest and shortest months were inversely correlated with height distribution. Conversely, for weight prediction, when controlled by height, the effective day lengths of the longest and shortest months were positively correlated with weight distribution. The regression coefficients were greater for the effective day length of the shortest month in both height and weight prediction. This phenomenon where the same two explanatory variables are negatively correlated with height and positively correlated with weight in a significant manner is rare, and there may be no physiological interpretation of this phenomenon other than one based on changes in thyroid hormone signaling. These distribution characteristics are common to the photoperiodicity by which seasonal breeding vertebrates reciprocally switch thyroid hormone signaling according to prior photoperiodic history through epigenetic functions. From these perspectives, thyroid hormone signaling in a certain region was assumed to be activated in summer according to the prior shorter winter day length and inactivated in winter according to the prior longer summer day length. Regarding the prevalence of obesity, the coexistence of longer summer and winter day lengths was thought to set body composition to be short and fat in early adolescence.

Evaluating the seasonality of growth in infants using a mobile phone application

It has been observed that growth velocity of toddlers and school children shows seasonal variation, while such seasonality is unknown in infants. The aim of this study was to examine whether growth velocity (length and weight) of infants differs by seasons. We assessed longitudinal measurement data obtained for 9,409 Japanese infants whose parents used the mobile phone application, "Papatto Ikuji", during the period from January 2014 to October 2017. On average, each infant had 4.8 entries for length and 5.4 entries for weight. The mean daily change in sex- and age-adjusted z-scores between two time points was estimated as the growth velocity during that period: ΔLAZ/day and ΔWAZ/day for length and weight, respectively. We analyzed 20,007 ΔLAZ/day (mean, -0.0022) and 33,236 ΔWAZ/day (mean, 0.0005) measurements, and found that ΔLAZ/day showed seasonal differences with increases during summer. We conducted a multilevel linear regression analysis, in which effects of age, sex, nutrition and season of birth were adjusted, showing significant difference in ΔLAZ/day between winter and summer with a mean ΔLAZ/day difference of 0.0026 (95%CI 0.0015 to 0.0036; P < 0.001). This seasonal difference corresponded to 13% of the average linear growth velocity in 6-month-old infants. A modest effect of nutrition on linear growth was observed with a mean ΔLAZ/day difference of 0.0015 (95%CI 0.0006 to 0.0025; P < 0.001) between predominantly formula-fed infants and breastfed infants. In conclusion, we observed that linear growth, but not weight gain, of Japanese infants showed significant seasonality effects represented by increases in summer and decreases in winter.

Vitamin D status and response to growth hormone treatment in prepubertal children with growth hormone deficiency

PURPOSE

To analyze whether vitamin D deficiency could condition the growth response to GH therapy, as well as to analyze if GH treatment modifies both seasonal variations and vitamin D levels in these patients.

METHODS

Retrospective study in 98 prepubertal children with GH deficiency (GHD), aged 4.1-8.9 years treated with GH. Growth rate and blood testing (calcium, phosphorus, IGF-I, 25(0H)D and PTH) were monitored at diagnostic and every six months until 24 months of treatment. A control group was recruited (247 healthy children, aged 3.8-9.7 years). The criteria of the US Endocrine Society were used for the definition of hypovitaminosis D.

RESULTS

There were no significant differences in vitamin D deficiency among control (12.5%) and GHD groups (15.3%) before starting treatment. Growth rate and IGF-1 and PTH increased (p < 0.05) during GH treatment, but there were no significant differences in calcium, phosphorus and 25(OH)D. There were no significant differences in growth rate and IGF-1, calcium and phosphorus levels in relation to the seasons along GH treatment. There was no correlation between 25(OH)D and IGF-1 during GH therapy. In every programmed control, patients with vitamin D deficiency showed lower growth rate (p < 0.05) compared to patients with vitamin D insufficiency or sufficiency.

CONCLUSION

GH treatment, at least during the first two years, does not modify the vitamin D levels. Vitamin D deficiency could condition the response to GH therapy so vitamin D monitoring should be considered as part of the routine evaluation of children with GH treatment.

Effects of altered photoperiod due to COVID-19 lockdown on pregnant women and their fetuses

Maternal circadian rhythms provide highly important input into the entrainment and programming of fetal and newborn circadian rhythms. The light-dark cycle is an important regulator of the internal biological clock. Even though pregnant women spend a greater part of the day at home during the latter stages of pregnancy, natural light exposure is crucial for the fetus. The current recommended COVID-19 lockdown might dramatically alter normal environmental lighting conditions of pregnant women, resulting in exposure to extremely low levels of natural daylight and high-intensity artificial light sources during both day and night. This article summarizes the potential effects on pregnant woman and their fetuses due to prolonged exposure to altered photoperiod and as consequence altered circadian system, known as chronodisruption, that may result from the COVID-19 lockdown.

Physiological mechanisms underlying children's circannual growth patterns and their contributions to the obesity epidemic in elementary school age children

Several studies since the 1990s have demonstrated that children increase their body mass index at a faster rate during summer months compared with the school year, leading some to conclude that the out-of-school summer environment is responsible. Other studies, however, have suggested that seasonality may play a role in children's height and weight changes across the year. This article reviews evidence for seasonal differences in the rate of children's height and weight gain and proposes potential physiological mechanisms that may explain these seasonal variations.

Day length may make geographical difference in body size and proportions: An ecological analysis of Japanese children and adolescents

There is a north-south gradient in the body heights of Japanese children. A hypothesis had previously been proposed that differences in thyroid hormone activity induced by geographical differences in effective day length (duration of photoperiod exceeding a predetermined light intensity) might cause the differences in height. If thyroid hormone is involved, the effect should extend to body weight. This study examined whether geographical differences in body height and weight can be explained in terms of thyroid hormone activity induced by geographical differences in the photoperiodic environment using prefecture-level anatomical data and Japanese Mesh Climatic Data. Multiple regression analysis demonstrated that the combination of effective day length and weight was statistically significant as a predictor of height. Controlling for body weight revealed that effective day length was inversely correlated with height. Multiple regression analysis revealed that a combination of effective day length and height was statistically significant as a predictor of weight. Controlling for height demonstrated that effective day length was positively correlated with weight. Assuming an inverse correlation between effective day length and thyroid hormone activity, these results appear to show that short day-length will increase the activity of thyroid hormone and contribute to increasing height, but will inhibit weight gain; in contrast, long day-length will decrease the activity of thyroid hormone and contribute to increasing weight but will inhibit height gain. Geographical differences in height, and weight, and part of the prevalence of obesity in Japanese children and early adolescents may be explained by geographical differences in effective day length.

Comparing the Behavioural Effects of Exogenous Growth Hormone and Melatonin in Young and Old Wistar Rats

Growth hormone (GH) and melatonin are two hormones with quite different physiological effects. Curiously, their secretion shows parallel and severe age-related reductions. This has promoted many reports for studying the therapeutic supplementation of both hormones in an attempt to avoid or delay the physical, physiological, and psychological decay observed in aged humans and in experimental animals. Interestingly, the effects of the external administration of low doses of GH and of melatonin were surprisingly similar, as both hormones caused significant improvements in the functional capabilities of aged subjects. The present report aims at discerning the eventual difference between cognitive and motor effects of the two hormones when administered to young and aged Wistar rats. The effects were tested in the radial maze, a test highly sensitive to the age-related impairments in working memory and also in the rotarod test, for evaluating the motor coordination. The results showed that both hormones caused clear improvements in both tasks. However, while GH improved the cognitive capacity and, most importantly, the physical stamina, the effects of melatonin should be attributed to its antioxidant, anxiolytic, and neuroprotective properties.

Chronobiological Hypothesis about the Association Between Height Growth Seasonality and Geographical Differences in Body Height According to Effective Day Length

Studies on growth hormone therapy in children have shown that height velocity is greater in summer than in winter and that this difference increases with latitude. It is hypothesized that summer daylight is a causative factor and that geographical distribution of body height will approximate the distribution of summer day length over time. This is an ecological analysis of prefecture-level data on the height of Japanese youth. Mesh climatic data of effective day length were collated. While height velocity was greatest during the summer, the height of Japanese youth was strongly and negatively correlated with the distribution of winter effective day length. Therefore, it is anticipated that summer height velocity is greater according to winter day length (dark period). This may be due to epigenetic modifications, involving reversible DNA methylation and thyroid hormone regulation found in the reproductive system of seasonal breeding vertebrates. If the function is applicable to humans, summer height growth may quantitatively increase with winter day length, and height growth seasonality can be explained by thyroid hormone activities that-induced by DNA methylation-change depending on the seasonal difference in day length. Moreover, geographical differences in body height may be caused by geographical differences in effective day length, which could influence melatonin secretion among subjects who spend a significant time indoors.

Decreased 6-Sulfatoxymelatonin Excretion in Male GH-Deficient Children and Adolescents

AIM

To evaluate melatonin secretion in a group of untreated and treated male growth hormone (GH)-deficient children and adolescents.

METHODS

We studied 44 male subjects: 8 untreated GH-deficient patients (GHDnt), 16 treated GH-deficient patients (GHDt) and 20 healthy children and adolescents as control group (CG). We measured urinary 6-sulfatoxymelatonin (6-SM) in total (24-hour samples), nocturnal (18.00-8.00 h) and diurnal samples (8.00-18.00 h). Levels of 6-SM were expressed as micrograms excreted per time interval and x0394; values (difference between nighttime and daytime values).

RESULTS

Significant differences were observed among the 3 groups of pediatric subjects studied for total 6-SM (p < 0.0001), nocturnal 6-SM (p < 0.0001) and x0394; values (p < 0.0001). Subsequent analysis showed significantly higher levels for total 6-SM, nocturnal 6-SM and nighttime-daytime x0394; in the CG versus the GHDnt (p < 0.01) and in the CG versus the GHDt group (p < 0.01). No significant correlations were found between 6-SM excretion and insulin-like growth factor-1 values in the children and adolescents studied.

CONCLUSIONS

GH-deficient patients showed lower levels of 6-SM. Our findings provide a different insight to a further understanding of some chronobiological disorders involved in GH deficiency in children.

Seasonal variations in growth and body composition of 8-11-y-old Danish children

BACKGROUND

Earlier studies on seasonality in growth reported the largest height gains during spring and largest body weight gains during autumn. We examined seasonality in height, body weight, BMI, fat mass index (FMI), and fat-free mass index (FFMI) among contemporary Danish 8-11-y olds.

METHODS

A total of 760 children from the OPUS School Meal Study provided >2,200 measurements on height, body weight, and composition between September and June. Average velocities were calculated using change-score analyses based on 3-mo intervals. As a complementary analysis, point velocities derived from estimated growth curves were fitted using semiparametric regression that included covariate adjustment and allowed flexible modeling of the time trend.

RESULTS

Average velocities showed the following trends: height was higher than the average (6.10 cm/y) in January-April. Body weight was below the average (4.02 kg/y) in August-January and above in January-May; BMI (average: 0.49 kg/ m(2)/y) and FFMI (average: 0.17 kg/m(2)/y) showed similar trends. In contrast, FMI was above the average (0.38 kg/m(2)/y) in November-March. Similar trends were seen for point velocities.

CONCLUSION

Our findings suggest seasonality in growth and body composition of Danish children. We recovered the well-known height velocity peak during spring time, but unlike earlier studies, we found coincident peaks in body weight, BMI, and FFMI velocities.

Seasonal variations in vitamin D in relation to growth in short prepubertal children before and during first year growth hormone treatment

PURPOSE

This study investigated the relationship between seasonal variations in 25-hydroxyvitamin D (25(OH)D) levels and growth in prepubertal children during both the pretreatment year and the first year of GH treatment.

METHODS

The study included 249 short prepubertal children with a broad range of GH secretion, GH(max) during a 24 h profile median 23; range 1-127 mU/L, 191 boys (mean age ± SD, 8.6 ± 2.6 years), 58 girls (7.5 ± 1.9 years) receiving GH treatment (mean 43 µg/kg/day; range 17-99 µg/kg/day). Serum 25(OH)D was measured using an automated IDS-iSYS immunoassay.

RESULTS

25(OH)D levels showed seasonal variation, and decreased significantly during GH treatment. 25(OH)D levels at start and first year reduction in 25(OH)D, correlated (-) with the first year growth response during treatment. The degree of GH secretion capacity within our study population of mainly non-GH deficient children and 25(OH)D sufficient (67 ± 29 nmol/L) had no influence on 25(OH)D levels. Growth during GH treatment were independent of seasonal variations in 25(OH)D. Multiple regression analysis showed that 25(OH)D levels at treatment start, together with auxological data and IGF-binding protein-(3)SDS, explained 61 % of the variation in first year gain in heightSDS.

CONCLUSION

25(OH)D levels were associated with first year growth response to GH and may be a useful contribution to future growth prediction models.

The seasonality of slipped upper femoral epiphysis--meta-analysis: a possible association with vitamin D

We performed a meta-analysis of studies evaluating the seasonality of slipped upper femoral epiphysis (SUFE). In addition we compared the monthly incidences of SUFE at latitudes greater than 40° with the established serum 25-hydroxyvitamin levels for children resident at a comparative latitude. In total 11 relevant studies were identified, involving 7451 cases of SUFE. There was significant variation in the month of onset of SUFE. The degree of variability increased with increasing latitude. The modal month of symptomatic onset was dependent upon latitude. At latitudes greater than 40°, the most common month of onset was August. At latitudes between 20° and 40°, this was earlier in the calendar year, around April. The seasonal variability was statistically significant (p<0.0001 and p<0.005 for latitudes >40° and 20°-40° respectively). The pattern of monthly fluctuation in onset of SUFE very closely mirrored the monthly pattern of variation for serum 25-hydroxyvitamin D3. There was a very strong positive correlation (Spearman rank rho = + 0.8, p = 0.001). There is a monthly variation in incidence of SUFE. The degree of variability increases with increasing latitude. There may be an association with vitamin D. We hypothesise that elevated serum 25-hydroxyvitamin D3 accelerates growth thus rendering the growth plate vulnerable to slippage in analogous manner to the pubertal growth spurt.

Effect of summer daylight exposure and genetic background on growth in growth hormone-deficient children

The response to growth hormone in humans is dependent on phenotypic, genetic and environmental factors. The present study in children with growth hormone deficiency (GHD) collected worldwide characterised gene–environment interactions on growth response to recombinant human growth hormone (r-hGH). Growth responses in children are linked to latitude, and we found that a correlate of latitude, summer daylight exposure (SDE), was a key environmental factor related to growth response to r-hGH. In turn growth response was determined by an interaction between both SDE and genes known to affect growth response to r-hGH. In addition, analysis of associated networks of gene expression implicated a role for circadian clock pathways and specifically the developmental transcription factor NANOG. This work provides the first observation of gene–environment interactions in children treated with r-hGH.

Kidney growth and renal functions under the growth hormone replacement therapy in children

OBJECTIVE

The aim of this study was to investigate the kidney growth and renal functions in children receiving recombinant human growth hormone (rhGH) treatment.

MATERIALS AND METHODS

A total of 37 children who received rhGH for 1.5 years before the study was started and 48 healthy controls were included at first evaluation. Hormone levels were determined and kidney sizes were measured by ultrasound. Kidney functions were assessed by serum creatinine and estimated glomerular filtration rate (eGFR). After 3 years of first evaluation, 23 patients were re-assessed.

RESULTS

Kidney sizes were found to be lower in rhGH received children compared with controls at first evaluation (p<0.05). Significant positive correlations were found between anthropometric measurements and kidney length and kidney volume (p<0.05). Height was the most significant predictor of kidney volume in rhGH received children (p<0.001). After 3-years of follow-up significantly increases were found in kidney length and volume compared with the first measurements (p<0.05). Increase percentage of body height was similar to increasing percent of kidney length and liver long axis (14.2%, 11.7.1% and 7.7%, respectively, p>0.05). Although no abnormal renal function test results were found at first and second evaluations; rhGH received children had significantly lower eGFR, at first evaluation, compared with controls; however, renal functions significantly increased after 3 years of follow-up (p<0.05).

CONCLUSIONS

In conclusion, effect rhGH treatment on kidney growth is parallel to growth in body height and other visceral organs. A 3-years rhGH treatment resulted in significant increases in renal functions.