Association of serum lipid concentrations, insulin resistance index and catch-up growth with serum cortisol/cortisone ratio by liquid chromatography tandem mass spectrometry in children born small for gestational age

Cortisol and Cortisone in Early Childhood in Very-Low-Birthweight Infants and Term-Born Infants

INTRODUCTION

Besides programming of the hypothalamic-pituitary-adrenal (HPA) axis, changes in the activity of 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) could contribute to the later metabolic and cardiovascular consequences of preterm birth.

OBJECTIVE

We compared serum cortisol, cortisone, and cortisol/cortisone ratio in early childhood in very-low-birthweight (VLBW) infants and term appropriate for gestational age (AGA) born infants.

METHODS

We included 41 VLBW infants, participating in the randomized controlled Neonatal Insulin Replacement Therapy in Europe trial, and 64 term AGA-born infants. Cortisol and cortisone were measured in blood samples taken at 6 months and 2 years corrected age (VLBW children) and at 3 months and 1 and 2 years (term children). At 2 years of (corrected) age (HDL) cholesterol, triglycerides, glucose, and insulin were also measured.

RESULTS

During the first 2 years of life, cortisol/cortisone ratio is higher in VLBW children compared to term children. In the total group of children, cortisol/cortisone ratio is positively related to triglycerides at 2 years of (corrected) age. In VLBW children, over the first 2 years of life both cortisol and cortisone are higher in the early-insulin group compared to the standard care group.

CONCLUSIONS

In VLBW infants, lower 11β-HSD2 activity probably contributes to the long-term metabolic and cardiovascular risks. In VLBW infants, early insulin treatment could affect programming of the HPA axis, resulting in higher cortisol and cortisone levels during early childhood.

Association of Serum Total Osteocalcin Concentrations With Endogenous Glucocorticoids and Insulin Sensitivity Markers in 12-Year-Old Children: A Cross-Sectional Study

Background: Osteocalcin (OC) is an osteoblast-derived marker of bone turnover that has recently been linked to glucose metabolism, glucocorticoid action, and cardiovascular risk. Objective: We determined whether serum total OC (tOC) is associated with cardiometabolic factors, such as insulin sensitivity (IS) markers and endogenous glucocorticoids in 12-year-old children. In addition, we assessed whether low birth weight or exposure to maternal preeclampsia affect tOC concentrations. Methods: In this cross-sectional study, 192 children (109 girls) were studied at 12 years of age. Seventy of them had been born small (SGA), 78 appropriate for gestational age (AGA), and 44 from preeclamptic pregnancies (PRE) as AGA. Blood pressure was measured, and fasting blood samples were collected for markers of glucose metabolism, osteoblast, adipocyte, and adrenocortical function. IS was estimated by Quantitative Insulin Sensitivity Check Index (QUICKI). Free cortisol index (FCI) was calculated as serum cortisol/corticosteroid binding globulin. Results: The highest tOC concentrations were detected in midpubertal children (Tanner B/G stage 3). The children in the highest tOC quartile (n = 48) had lower body mass index (BMI), waist-to-height ratio, diastolic blood pressure, leptin, cortisol/cortisone ratio and FCI, and higher insulin-like growth factor I (IGF-I), IGF-binding protein-1 (IGFBP-1), IGFBP-3, and alkaline phosphatase (ALP) than those in the lower tOC quartiles (p < 0.02 for all). QUICKI was similar in these subgroups. In logistic regression analysis, pubertal developmental stages 2 and 3, high ALP, IGF-I, and low FCI and BMI (p < 0.02 for all) were associated independently with higher tOC. The means of serum tOC and IS markers were similar in the SGA, AGA, and PRE subgroups. Conclusions: In both sexes, the highest tOC levels were detected in midpubertal children reflecting the fast pubertal growth phase. Higher tOC levels were associated with lower BMI and FCI, whereas no association was found with IS. Birth weight or exposure to preeclampsia had no effect on tOC concentrations.

Differences in insulin resistance markers between children born small for gestational age or born preterm appropriate for gestational age

AIM

To evaluate the impact of prenatal or postnatal compromised environment on glucose homoeostasis in children born preterm and appropriate for gestational age or small for gestational age (SGA) at term.

METHOD

Seventy-seven children (median 9.9 years, range 8.5-10) born at Karolinska Hospital were allocated to three groups: 21 subjects born before 30 weeks of gestational age (preterm), 26 SGA at term and 30 at term with appropriate birth weight (control). Anthropometric measurements were taken, and fasting blood samples for haemoglobin A1c, glucose, insulin, IGFBP-1, IGF-1 and lipid profile were taken. Glucose, insulin and IGFBP-1 samples were taken at 0, 30 and 120 min during an oral glucose tolerance test (OGTT).

RESULTS

Subjects born preterm or SGA were shorter and thinner compared with Controls. After adjustment for body mass index (BMI), the SGA group had higher basal insulin levels (p = 0.029), higher homoeostasis model assessment-insulin resistance (p = 0.012) and lower whole-body insulin sensitivity index (p = 0.007) than Controls. IGFBP-1 decrease during OGTT was attenuated in the Preterm group compared with the Control (p = 0.045) and SGA groups (p = 0.007).

CONCLUSION

The higher fasting insulin level in the SGA children, adjusted for BMI, could indicate peripheral insulin resistance. Preterm born children had reduced suppression of IGFBP-1 during OGTT, suggesting hepatic insulin resistance.

Perinatal programming of central obesity and the metabolic syndrome: role of glucocorticoids

Intrauterine growth retardation (IUGR) is associated with increased prevalence, at the adult age, of central obesity, the metabolic syndrome, and its complications (type 2 diabetes and coronary heart disease). Programming of the corticotropic function is one of the mechanisms underlying the above-mentioned phenomenon. An increased passage of active glucocorticoids from the mother to the fetus can act, at the central nervous system level, to program an enhanced response to stress and, at the peripheral level, in adipose tissue to induce an increased local glucocorticoid exposure and sensitivity. In addition to an improvement of the health of pregnant women, early diagnosis of metabolic and hormonal disturbances is important in children with IUGR, in order to prevent a compensatory catch-up growth and its subsequent obesity, and to set up a therapeutic intervention against the deleterious consequences of hypercorticism.

11β-Hydroxysteroid dehydrogenase type 1 activity in short small-for-GA children and in response to GH therapy

Small for GA (SGA) children are at risk for developing the metabolic syndrome. Those who do not catch up, and remain short (SSGA), may benefit from GH therapy. 11β Hydroxysteroid dehydrogenase type 1 (11β-HSD-1) is expressed in visceral fat and is implicated in metabolic morbidity. We hypothesized that SSGA children will have increased basal and glucocorticoid (GC)-stimulated 11β-HSD-1 activity. Twenty SSGA children, aged 7.1 ± 1 y (mean ± SD), were studied before and while on GH therapy and compared with 12 normal age-matched controls. 11β-HSD-1 activity was evaluated by gas chromatography mass spectrometry (GCMS) of urinary steroid product/substrate ratios. GC-stimulated 11β-HSD-1 activity was assessed after overnight dexamethazone (DEX), by oral cortisone conversion to cortisol. In SSGA children, 11β-HSD-1 activity was lower (p < 0.05) and GC-stimulated activity enhanced. SSGA children had maximal cortisol generation of 883 ± 108 compared with 690 ± 63 nmol/L in controls (p < 0.04). GH treatment suppressed 11β-HSD-1 activity. GC-stimulated enzyme activity correlated negatively with GA (r = -0.53, p < 0.01) and birth weight (r = -0.55, p < 0.01). SSGA is associated with enhanced GC-stimulated 11β-HSD-1 activity. This may be programmed in utero, as it is not a function of body composition or secondary metabolic derangement. GH therapy normalizes GC-stimulated 11β-HSD-1 activity.

Determination of cortisol production rates with contemporary liquid chromatography-mass spectrometry to measure cortisol-d(3) dilution after infusion of deuterated tracer

OBJECTIVES

Measurement of 24-h cortisol production rate (CPR) using steady-state infusion of deuterated cortisol and analysis of stable-isotope dilution by MS is a valuable tool to examine hypothalamic-pituitary-adrenal axis activity in humans. We have developed and validated an improved method for measuring cortisol dilution with contemporary LC-MS technology.

DESIGN AND METHODS

Plasma samples and calibrators were extracted with ethylacetate. LC-MS was performed with a Surveyor HPLC and TSQ Quantum triple-quadrupole mass spectrometer equipped with an atmospheric pressure chemical ionization (APCI) source.

RESULTS

Selectivity was improved over previous methods via elimination of an interferent identified as 20β-dihydrocortisol. The LLOQ for cortisol-d(3) was 2.73nmol/L and LOD 1.37nmol/L. Plasma calibrators were linear over the concentration range 1.5-10% cortisol-d(3), with correlation coefficients >0.995.

CONCLUSIONS

This APCI LC-MS method offers simplified sample work-up and analysis and enables selective detection of the low concentration of cortisol-d(3) infused for determination of 24-h CPR.

Effects of intrauterine exposure to synthetic glucocorticoids on fetal, newborn, and infant hypothalamic-pituitary-adrenal axis function in humans: a systematic review

BACKGROUND

Synthetic glucocorticoids are commonly used in reproductive medicine. Fetal organ systems are highly sensitive to changes in the intrauterine environment, including overexposure to glucocorticoids. Structural and functional alterations resulting from such changes may persist throughout life and have been associated with diverse diseases. One system that could be particularly sensitive to fetal glucocorticoid overexposure is the hypothalamic-pituitary-adrenal (hpa) axis. Many human studies have investigated this possibility, but a systematic review to identify consistent, emergent findings is lacking.

METHODS

We systematically review 49 human studies, assessing the effects of intrauterine exposure to synthetic glucocorticoids on fetal, neonate, and infant hpa function.

RESULTS

Study quality varied considerably, but the main findings held true after restricting the analyses to higher-quality studies: intrauterine exposure to synthetic glucocorticoids reduces offspring hpa activity under unstimulated conditions after pain but not pharmacological challenge. Although reduced unstimulated hpa function appears to recover within the first 2 wk postpartum, blunted hpa reactivity to pain is likely to persist throughout the first 4 months of life. There is some evidence that the magnitude of the effects is correlated with the total amount of glucocorticoids administered and varies with the time interval between glucocorticoid exposure and hpa assessment.

CONCLUSIONS

This systematic review has allowed the demonstration of the way in which intrauterine exposure to various regimens of synthetic glucocorticoids affects various forms of hpa function. As such, it guides future studies in terms of which variables need to be focused on in order to further strengthen the understanding of such therapy, whilst continuing to profit from its clinical benefits.

Steroid measurement with LC-MS/MS in pediatric endocrinology

The liquid chromatography-tandem mass spectrometry (LC-MS/MS) is an increasingly common tool in the clinical laboratory. Established applications include routine assays for detecting inborn errors of metabolism and for monitoring therapeutic drugs and steroids. Steroid profiling is a very effective method for distinguishing almost all steroid related disorders. It allows accurate diagnosis and is very useful in many clinical situations. Most methods for the determination of steroid hormones are based on immunoassays, which are rapid and easy to perform. However, the reliability of steroid immunoassays has been shown to be doubtful because of the lack of specificity and of matrix effects. Immunological methods, especially direct assays, often overestimate true steroid values. This is of particular importance in the newborn period and in early infancy. Problems with steroid immunoassays have further been reported for female patients or when analysing different media, e.g. saliva. Patient follow-up over time or between laboratories, as well as longitudinal studies are extremely difficult. In contrast to immunoassays, which allow the measurement of only a single steroid at a time, LC-MS/MS has the advantage that a wide spectrum of steroid hormones can be measured simultaneously. The applicability for clinical samples and problems in pediatric endocrinology will be discussed.

Catch-up growth in body mass index is associated neither with reduced insulin sensitivity nor with altered lipid profile in children born small for gestational age

OBJECTIVE

Low birth weight is a risk factor for coronary heart disease. Persons who have coronary events as adults tend to have been small at birth and thin at 2 yr of age, after which they tended to increase their body mass index (BMI). Our aim was to determine whether BMI gain is associated to alterations in insulin sensitivity and/or lipid profile in children born small for gestational age (SGA).

DESIGN

Retrospective case-control study.

METHODS

We studied 78 children (mean age 7.8+/-2.5 yr): 26 SGA children with catch-up growth in BMI (CGB-SGA) (BMI= 10th to 75th centile), 26 SGA without catch-up growth (NCGB-SGA) (BMI<10th centile), and 26 appropriate for gestational age (AGA) control children (BMI: 10th to 75th centile). For each CGB-SGA child, we selected an NCGB-SGA and an AGA child of the same gender, age (within 1 yr), and pubertal status. SGA children were also subdivided into 2 groups according to post-natal catch-up growth in height (CGH).

RESULTS

Glucose was significantly lower in NCGBSGA than AGA group (p=0.02). No significant differences in fasting insulin, fasting glucose/insulin ratio, homeostasis model assessment, quantitative insulin-sensitivity check index, and lipid profile were found among the 3 groups. HDL-cholesterol proved significantly reduced in SGA children with post-natal CGH (p=0.02).

CONCLUSIONS

Our findings do not support the hypothesis of early alterations in insulin sensitivity and lipid metabolism in CGB-SGA subjects during childhood provided that BMI remains within the normal range. Finally, the finding of reduced HDL-cholesterol levels in CGH-SGA children suggests detrimental metabolic effects of the height gain.

Uteroplacental insufficiency after bilateral uterine artery ligation in the rat: impact on postnatal glucose and lipid metabolism and evidence for metabolic programming of the offspring by sham operation

Ligation of the uterine arteries (LIG) in rats serves as a model of intrauterine growth restriction and subsequent developmental programming of impaired glucose tolerance, hyperinsulinemia, and adiposity in the offspring. Its impact on lipid metabolism has been less well investigated. We compared parameters of glucose and lipid metabolism and glucocorticoid levels in the offspring of dams that underwent either LIG or sham operation (SOP) with those of untreated controls. Blood parameters including insulin, leptin, and visfatin as well as body weight, food intake, and creatinine clearance were recorded up to an age of 30 wk. Glucose tolerance tests were performed, and both leptin and visfatin expression in liver, muscle, and epididymal and mesenteric fat was quantified by RT-PCR. After catch-up growth, weight gain of all groups was similar, despite lower food intake of the LIG rats. LIG offspring showed impaired glucose tolerance from the age of 15 wk as well as elevated glycosylated hemoglobin and corticosterone levels. However, the body fat content of both LIG and SOP animals increased relative to controls, and both showed elevated triglyceride, total cholesterol, and leptin levels as well as a reduced proportion of high-density lipoprotein cholesterol. Thus, use of the LIG model requires both SOP and untreated controls. Although only LIG is associated with impaired glucose tolerance, pathogenic programming of the lipid metabolism can also be induced by SOP. Visfatin does not appear to be involved in the disturbed glucose metabolism after intrauterine growth restriction and may represent only a marker of fat accumulation.

Cortisol-cortisone ratios in small for gestational age (SGA) children without postnatal catch-up growth

OBJECTIVE

Low birthweight is a risk factor for metabolic and cardiovascular disorders in later adult life. Changes in the activity of 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) and the consequent disequilibrium between cortisol (F) and cortisone (E) are thought to be a key mechanism for these effects. We investigated whether prenatal programming leads to alterations in F/E ratios on a systemic level.

DESIGN, PATIENTS AND METHODS

In a cross-sectional, retrospective study we analysed sera of 132 children born small for gestational age (SGA) (aged 2-13 years) with persistent short stature [< -2 standard deviation score (SDS)] and of 25 children born appropriate for gestational age (AGA) (aged 4-11 years) with normal body height. Thirty-one per cent of the SGA and 44% of the AGA children were born preterm. Serum E and F concentrations were measured using tandem mass spectrometry. To exclude species-specific effects, we studied the 11beta-HSD system by measuring the ratio of corticosterone (B) to dehydrocorticosterone (11OH-B) in rats that were born SGA after protein restriction of the female dams during pregnancy.

RESULTS

F, E and the F/E ratio in serum did not differ in these children when comparing SGA to children who were born AGA and had normal height. The concentrations were independent of weight and length SDS at birth as well as gestational age. In rats born SGA, the B/11OH-B ratio was not different to that in normal control animals at 6, 11 and 15 weeks of life.

CONCLUSION

We found no alterations in systemic cortisol-cortisone conversion either in short children born SGA or in SGA rats. However, local modifications of the 11beta-HSD system may be possible.

Diabetic pregnancy in rats leads to impaired glucose metabolism in offspring involving tissue-specific dysregulation of 11beta-hydroxysteroid dehydrogenase type 1 expression

Population-based studies have shown that the offspring of diabetic mothers have an increased risk of developing obesity, insulin resistance, type 2 diabetes and hypertension in later life. To investigate mechanism for the high incidence of metabolic diseases in the offspring of diabetic mothers, we focused on the tissue-specific glucocorticoid regulation by 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) and studied offspring born to streptozotocin-induced diabetic rats. The body weights of newborn rats from diabetic mothers were heavier than those from control mothers. Offspring born to diabetic mothers demonstrated insulin resistance and mild glucose intolerance after glucose loading at 10 weeks and showed significantly increased 11beta-HSD1 mRNA and enzyme activity in adipose tissue at 12 weeks of age without obvious obesity. Hepatic 11beta-HSD1 mRNA was also elevated. We propose that the 11beta-HSD1 in adipose tissue and liver may play a key role in the development of metabolic syndrome in the offspring of diabetic mothers. Tissue-specific glucocorticoid dysregulation provides a candidate mechanism for the high incidence of metabolic diseases in the offspring of diabetic mothers. Therefore early analyses before apparent obesity are needed to elucidate the molecular mechanisms that may be programmed during the fetal period.

Cord blood cortisol level is lower in growth-restricted newborns

AIM

To establish the difference in plasma cortisol concentrations between newborns with intrauterine growth-restricted (IUGR) and appropriate for gestational age (AGA) birthweights.

SUBJECTS AND METHODS

We measured plasma cortisol concentrations in the umbilical venous cord blood of 68 IUGR newborns and 71 AGA birthweight newborns. All newborns were delivered in term, vaginally, in the morning, within 8 hours and had APGAR scores greater or equal to eight.

RESULTS

There was no significant difference between compared groups according to maternal age, parity, gestational age and neonatal gender. Neonatal plasma cortisol levels were significantly lower in the IUGR (median: 312.3 mmol/L, min-max: 158.9-588.1 mmol/L) compared to the AGA group (median: 458.7 mmol/L, min-max: 314.5-718.5 mmol/L) (Mann-Whitney U-test; P<0000). The probability of having a cortisol plasma level greater than or equal to 458.7 mmol/L for IUGR newborns was only 1:12, and to have cortisol plasma level less than or equal to 312.3 mmol/L for AGA newborns was much lower (0:34). In the range of plasma cortisol level between 312.3 mmol/L and 458.7 mmol/L, no statistically significant difference in the plasma cortisol level between IUGR and AGA newborns was found.

CONCLUSIONS

Neonatal plasma cortisol level is lower in the IUGR compared to the AGA group. Our results suggest that endocrine relationships seem to be lost in a specific group of the IUGR newborns. Although we usually tend to simplify the problem and declare only one cause, this time it is impossible. It is probable that the cause is hidden in small and insufficient placenta with deranged auto-regulation of placental 11beta-HSD-2 mechanism.

Catch-up growth in small for gestational age babies: good or bad?

PURPOSE OF REVIEW

Most small for gestational age infants show rapid early postnatal growth and weight gain. Increasing trends towards childhood overweight and its metabolic consequences, and their epidemiological associations with lower birth weight, have led to critical assessments of the benefits and disadvantages of rapid early growth.

RECENT FINDINGS

In the last 12 months, three systematic reviews have described the consistent association between rapid infancy growth and subsequent obesity risk in childhood and later life. Recent studies have also described the very early development of insulin resistance in small for gestational age children who show catch-up growth, and this insulin resistance may, in turn, adversely affect body composition, growth and puberty. Long-term randomized trials of growth hormone therapy, however, remind us of the persisting short stature and significant adult height deficit in untreated children without early spontaneous catch-up.

SUMMARY

Even in modern societies with low rates of childhood infection and mortality, the small for gestational age infant may face a dilemma over whether or not to catch up. Current nutritional strategies that promote catch-up growth should include some monitoring of weight-for-length and adiposity, and the concept of 'healthy catch-up growth' should be the goal of future research.