Serum leptin levels and relationship with maternal weight gain at term among obese and non-obese pregnant women in Enugu, Nigeria: a comparative cross-sectional study

OBJECTIVE

To determine and compare the mean maternal serum leptin levels, the prevalence of high serum leptin levels and mean gestational weight gain at term among obese and non-obese pregnant women in Enugu, Nigeria.

METHODS

This cross-sectional comparative study enrolled obese and non-obese pregnant women. The serum leptin levels of the women were determined using an enzyme-linked immunosorbent assay kit. Anthropometric and sociodemographic data were obtained and compared. Mean weight gain during pregnancy was determined.

RESULTS

A total of 170 pregnant women were included in the study. The mean ± SD serum leptin level (99.39 ± 50.2 ng/ml) and the prevalence of hyperleptinaemia (81 of 85 patients; 95.3%) among the obese pregnant women at term were significantly higher than those of the non-obese pregnant women (48.98 ± 30.35 ng/ml/65 of 85 patients; 76.5%). The mean percentage weight gain was significantly higher in the non-obese women compared with the obese women at term. The predictors of high maternal serum leptin level at term among the participants were the employment status and levels of education of the participants.

CONCLUSION

Maternal serum leptin level, maternal weight gain and prevalence of hyperleptinaemia at term were significantly higher in the obese compared with the non-obese pregnant women.

Sex- and body mass index-specific reference intervals for serum leptin: a population based study in China

Background

Leptin is a peptide hormone secreted by adipose tissue and is an important determinant of obesity and its complications. The purpose of this study was to establish sex- and body mass index (BMI)-specific reference intervals for serum leptin in a Chinese population and investigate the factors influencing leptin concentrations.

Methods

Fasting serum leptin levels were assayed in 469 men and 773 women from randomly sampled Chinese residents. Blood glucose, insulin, hemoglobin A1c (HbA1c), liver enzymes, blood lipid profiles, creatinine, and uric acid (UA) levels were measured. Pearson’s correlation coefficient and multiple linear regression analyses were used to estimate the relationship between serum leptin level and other variables. The reference intervals were determined by the 2.5th and 97.5th percentiles.

Results

The mean ± standard deviation serum leptin level was much higher in women (20.92 ± 12.96 ng/mL) than in men (6.45 ± 5.53 ng/mL). The reference interval of serum leptin was 0.33–19.85 ng/mL in men and 3.60–54.86 ng/mL in women. The specific reference intervals of serum leptin in men with BMI of 20 to < 25 and 25 to < 27.5 kg/m² were 0.42–12.32 and 2.17–20.22 ng/ml, respectively. The specific reference intervals of serum leptin in women with BMI of 20 to < 25 and 25 to < 27.5 kg/m² were 4.11–38.09 and 8.27–48.66 ng/ml, respectively. BMI was significantly correlated with Ln (leptin) both in men (r = 0.698, P < 0.001) and women (r = 0.626, P < 0.001). In multivariate linear regression analysis, serum leptin was correlated with BMI, homeostasis model assessment of insulin resistance (HOMA-IR), UA in women, and plus triglyceride (TG) in men. The variance in serum leptin levels could be partially explained by these variables in both women (adjusted R² = 0.447) and men (adjusted R² = 0.552). In participants with leptin levels higher than the reference intervals, significantly higher levels of HOMA-IR, low-density lipoprotein cholesterol (LDL-C), UA, a higher proportion of central obesity (waist circumference [WC] > 90 cm), and metabolic syndrome were found in men, and significantly higher levels of HOMA-IR, UA and a higher proportion of central obesity (WC > 85 cm) were found in women.

Conclusion

This is the first study to establish sex- and BMI-specific reference intervals of leptin for both sexes in a large Chinese population. Serum concentration of leptin was predicted by BMI, HOMA-IR, UA in women, and TG in men.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12986-022-00689-x.

Association between obesity-associated markers and semen quality parameters and serum reproductive hormones in Chinese infertile men

BACKGROUND

The current evidence on the association between obesity-associated markers and semen quality, serum reproductive hormones and lipids remains inconsistent. In this study, we tested the hypothesis that, in infertile Chinese men, body mass index (BMI) negatively correlates with sperm concentration, serum total testosterone (TT), and high-density lipoprotein cholesterol (HDL-C). The relationship between other obesity-associated markers and semen quality parameters, serum reproductive hormones, lipids and leptin were also investigated.

METHODS

181 Chinese infertile men were recruited from September 2018 to September 2019. Their obesity-associated markers, semen parameters, and serum reproductive hormones, lipids and leptin were detected. Statistical analysis was performed to assess the relationship between obesity-associated markers and semen quality, serum reproductive hormones, lipids and leptin.

RESULT(S)

Statistically negative correlation was found between other obesity-associated markers (e.g. waist-to-hip ratio and waist-to-height ratio) and semen parameters (e.g. sperm concentration, ratio of progressive motility and ratio of non-progressive motility), while no significant correlation was found between BMI and semen quality, serum reproductive hormones, lipids and leptin. Ratio of morphologically normal sperm was negatively correlated with serum lipids including total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C), leptin and seminal superoxide dismutase. Ratio of progressive sperm, sperm concentration and ratio of morphologically normal sperm exhibited significantly lower values in overweight group than normal group. Estradiol (E2) and E2/TT were significantly higher in obese group than normal group, while TT level was significantly lower in obese group than normal group. Univariate and multivariate analysis indicated that TC was significantly associated with BMI. Serum leptin concentration was positively correlated with seminal leptin concentration in overweight and obese groups.

CONCLUSION(S)

No significant correlation was found between BMI and sperm concentration, serum TT and HDL-C, while other obesity-associated markers were found to negatively correlate with sperm concentration, ratio of progressive motility and ratio of non-progressive motility. Statistically significant correlations between serum reproductive hormones, lipids and leptin also existed in Chinese infertile men.

Serum leptin in diabetic nephropathy male patients from Gaza Strip

OBJECTIVE

To assess serum leptin in diabetic nephropathy male patients from Gaza Strip.

MATERIALS AND METHODS

This case-control study comprised 132 type 2 diabetic patients and 44 non-diabetic controls. The diabetic patients were classified into three groups; 44 normoalbuminurics, 44 microalbuminurics and 44 macroalbuminurics. Data were obtained from questionnaire interview, and biochemical analysis of blood and urine samples. Patients and controls were matched for age and body mass index (BMI).

RESULTS

Serum leptin was significantly higher in micro- and macro-albuminuric patients (14.6 ± 11.7 and 15.6 ± 13.5 ng/ml) than controls and normoalbuminurics (5.9 ± 4.0 and 8.1 ± 7.6 ng/ml) with P < 0.05. In general, serum glucose, urea, createnine, cholesterol, triglycerides, low density lipoprotein cholesterol (LDL-C), urinary albumin and albumin creatinine ratio (ACR) were increased in diabetic groups compared to non-diabetics, and reaching their maximum increase in macroalbuminurics whereas high density lipoprotein cholesterol (HDL-C), urinary creatinine and glomerular filtration rate (GFR) were decreased reaching its maximum decrease in macroalbuminurics. Serum leptin showed significant positive correlations with diabetes duration (r = 0.188, P = 0.020), glucose (r = 0.298, P < 0.001), cholesterol (r = 0.323, P < 0.001), triglycerides (r = 0.361, P < 0.001), LDL-C (r = 0.248, P = 0.001) and urinary albumin (r = 0.256, P = 0.001) whereas negative significant correlations were found with HDL-C (r = -0.313, P < 0.001) and urinary creatinine (r = -0.202, P = 0.007).

CONCLUSION

The comitant raise of serum leptin with urinary albumin combined with decrease in GFR makes leptin eligible candidate as a biomarker for progression towards diabetic nephropathy in type 2 diabetes.

Leptin as a Predictive Marker in Unexplained Infertility in North Indian Population

INTRODUCTION

According to WHO, the primary infertility in India is about 3.9% (age-standardized to 25-49 year) and 16.8% (age-standardized to 15-49 year), using the "age but no birth" definition. Several factors which affect fertility include low sperm production in men, poor egg quality and blocked fallopian tubes in women and also hormonal imbalances. Leptin plays a critical role in women's reproduction and neuroendocrine health. It is used for treating exercise-induced bone loss, eating disorders and infertility.

AIM

To evaluate the serum leptin levels in Indians and to ascertain the relationship between serum leptin levels, Unexplained Infertility (UI) and related variables [height, weight, Waist Hip Ratio (WHR), Body Mass Index (BMI)] between obese infertile, non-obese infertile and healthy subjects.

MATERIALS AND METHODS

The present case-control study was conducted at the Department of Obstetrics and Gynaecology, King George's Medical University (KGMU), Lucknow, India and funded by Department of Science and Technology, New Delhi, India. The study included 229 female participants in the age group of 18-40 years (120 cases and 109 controls) who were randomly selected. The blood samples were collected from the Infertility Clinic, Queen Mary's Hospital, KGMU, Lucknow, India. All the participants underwent complete physical examination. Initially, the participants were categorized into fertile and infertile groups, they were further divided on the basis of BMI, normal (BMI- 18.5-24.5) and overweight or obese (BMI≥25). Leptin level was measured by Active Human Leptin ELISA kit and BMI of all subjects was calculated in kg/m² (weight in kg and height in m).

RESULTS

A highly positive linear correlation (R=0.754, p<0.001) was found between BMI and serum leptin in unexplained infertile women, which indicates a strong relationship between BMI and serum leptin. The variation in serum leptin is explained by the independent variable, BMI. There was a partial positive linear correlation between BMI and serum leptin in the control group. Statistically there was no significant correlation (R=0.109, p=0.258) between BMI and serum leptin in the control group.

CONCLUSION

The present study clearly demonstrates that level of leptin is higher in unexplained infertile than in the fertile group, and also shows that a strong relationship exists between BMI and serum leptin in the obese group. Serum leptin level was significantly higher in obese than non-obese subjects. Thus, leptin is an important factor for normal reproductive function. Obesity, the main cause of infertility may be controlled by regulating the leptin concentration.

The role of adiposity in the relationship between serum leptin and severe major depressive episode

To assess the role that adiposity plays in the association between leptin and major depressive episode (MDE), we analyzed the data of 1046 men and 1359 women aged 20-39 years, who completed an interview and had blood collected as a part of the National Health and Nutrition Examination Survey (NHANES) between 1991 and 1994. Waist-hip ratio (WHR) was used as an indicator of adiposity. MDE was assessed with the Diagnostic Interview Schedule. For normal-WHR women, the prevalence of MDE was reversely associated with leptin levels, 13.7(4.4)%, 12.2(4.0)% and 2.3(1.8)% respectively for lower, interquartile, and upper quartile. For abnormal-WHR women, the prevalence of MDE was positively associated with leptin, 6.1(2.3)%, 9.1(2.4)% and 20.0 (3.8) respectively for the three leptin levels. Compared to women with lower quartile of leptin, the odds ratio of MDE for women with upper quartile was 0.09 (0.01-0.98) for normal-WHR women but 4.35 (1.55-12.2) for abnormal-WHR women. No moderating effects were observed among men. Using BMI in place of WHR revealed similar findings. The association between MDE and leptin is moderated by adiposity. High leptin levels are associated with low odds of MDE among women with normal adiposity but high odds among women with abnormal adiposity.

Assessment of left ventricular mass index could predict metabolic syndrome in obese children

Background

Childhood obesity is a major risk factor for cardiovascular diseases in children and adults.

Objectives

The purpose of this study was to evaluate the serum leptin level and the cardiac changes in normotensive obese children and to study the relationship between left ventricular mass index (LVMI) and serum leptin with the parameters of metabolic syndrome (MS) in obese children.

Methods

This study was conducted in al Jeddani Hospital and Ibn Sina College Hospital in Saudi Arabia in the period from July 2012 to December 2013, and included 82 obese children. Their mean age was 10.2 ± 2.8 years; they were divided into 25 obese children with MS and 57 obese children without MS, and 40 healthy age- and sex-matched children were also included in the study as a control group. All children were subjected to clinical assessment including standing height, body weight, body mass index (BMI), waist circumference (WC), and blood pressure measurements. All children received an echocardiographic examination (2-dimensional, M-mode, Doppler, and tissue Doppler echocardiograpy) and laboratory assessment of serum leptin level, fasting glucose, fasting insulin, the homeostatic model assessment for insulin resistance (HOMA) index, total cholesterol, triglycerides, and high- and low-density lipoprotein profile.

Results

BMI, BMI standard deviation score, WC, fasting glucose, fasting insulin, HOMA index and the serum leptin level were significantly higher in obese children compared to control group (p < 0.05). The LVMI were increased in the obese compared to the control group (p < 0.001) while left ventricle systolic and diastolic functions did not differ in obese versus control group (p > 0.05). There was a significant positive correlation between both LVMI and serum leptin level in comparison to BMI, WC, fasting glucose, fasting insulin, HOMA, triglycerides, and low-density lipoprotein in all obese children, especially the MS group. However, there was a significant negative correlation between both LVMI and serum leptin level in comparison to high-density lipoprotein.

Conclusion

Assessment of LVMI as routine echocardiographic examinations and serum leptin level might be a feasible and reliable method for the evaluation of obesity and its related cardiovascular risks during childhood that can predict metabolic syndrome and insulin resistance.

Effects of zinc supplementation on serum zinc and leptin levels, BMI, and body composition in hemodialysis patients

PROJECT

The aim of this study was to determine the effects of zinc supplementation on serum zinc and leptin levels as well as on anthropometric status and some biochemical parameters in hemodialysis (HD) patients.

PROCEDURE

In this randomized, double-blind, and placebo-controlled trial, sixty HD patients were randomly divided into groups to receive a daily supplement of 100mg elemental Zn (supplemented group) or placebo (control group) for 60 days. Anthropometric measurements were taken using standard calibrated instruments. Serum zinc and leptin levels were determined by atomic absorption and ELISA method respectively before and after intervention.

RESULTS

Zinc supplementation resulted in significant increase in the mean serum zinc level in the experimental group while changes observed in the placebo group were not significant. The mean serum leptin in women part of the experimental group was decreased significantly after supplementation. After adjusting for age, BMI, body fat (%), serum zinc and dietary Zn intake, a negative and significant association was observed between serum zinc and leptin levels in all subjects (β=-0.33, P=0.03) as a result of Zn supplementation.

CONCLUSIONS

More studies are needed to clarify the mechanisms by which serum leptin level is influenced as a result of zinc supplementation in HD patients.

Gender differences in serum leptin concentrations from umbilical cord blood of newborn infants born to nondiabetic, gestational diabetic and type-2 diabetic mothers

To investigate gender differences, if any, in leptin concentrations from umbilical cord blood of new born infants of mothers with type 2 diabetes mellitus (DM), gestational diabetes mellitus (GDM), and Non diabetic (ND) at delivery. Serum leptin concentrations were measured in 105 newborns (53 males and 52 females in the three groups). Blood was taken from the umbilical cord of the babies at delivery. Maternal anthropometric measurements were recorded within 48 hours after delivery. Pearson correlation coefficient was used to explore the relationship between serum leptin concentrations and anthropometric measures of the fetus and their mother. Both Serum leptin level and serum C-peptide was measured by chemiluminescence based ELISA. The median range of leptin concentration in cord blood was ND group: Male [13.91 (3.22 - 47.63)], Female [16.88 (2 - 43.65)]; GDM group: Male [32 (7 - 76.00)], Female [36.73 (4.80 - 81.20)]; DM group: Male [20.90 (2 -76.00)], Female [32 {2.58 - 80.67)]. Cord serum leptin levels correlated with birth weight(r=0.587, p=0.0001), ponderal index (PI) (r=.319, p=0.024)of the babies and body mass index (BMI) (r=-0.299, p=0.035) of their mothers but did not correlate with gestational age, cord serum C-peptide concentration or placental weight at delivery. Leptin concentrations were higher in the female fetus in comparison to the male fetus. Birth weight of the female fetuses were also higher than that of male fetus. We found that there are very strong associations between cord leptin concentrations at delivery and birth weight, ponderal index of the baby, body mass index of the mothers with Type 2 DM. We also found that high leptin levels could represent an important feedback modulator of substrate supply and subsequently for adipose tissue status during late gestation or adipose tissue is the major determinant of circulating leptin levels.