Low circulating leptin levels in protein-energy malnourished chronically ill elderly patients

Serum Leptin Levels, Nutritional Status, and the Risk of Healthcare-Associated Infections in Hospitalized Older Adults

We aimed to determine whether serum leptin levels are predictive of the occurrence of healthcare-associated infections (HAIs) in hospitalized older patients. In a prospective cohort, 232 patients had available data for leptin and were monitored for HAIs for 3 months. Admission data included comorbidities, invasive procedures, the Mini Nutritional Assessment (MNA), BMI, leptin, albumin and C-reactive protein levels, and CD4 and CD8 T-cell counts. Multivariate logistic regression modelling was used to identify predictors of HAIs. Of the 232 patients (median age: 84.8; females: 72.4%), 89 (38.4%) experienced HAIs. The leptin level was associated with the BMI (p < 0.0001) and MNA (p < 0.0001) categories. Women who experienced HAIs had significantly lower leptin levels than those who did not (5.9 μg/L (2.6–17.7) and 11.8 (4.6–26.3), respectively; p = 0.01; odds ratio (OR) (95% confidence interval): 0.67 (0.49–0.90)); no such association was observed for men. In a multivariate analysis of the women, a lower leptin level was significantly associated with HAIs (OR = 0.70 (0.49–0.97)), independently of comorbidities, invasive medical procedures, and immune status. However, leptin was not significantly associated with HAIs after adjustments for malnutrition (p = 0.26) or albuminemia (p = 0.15)—suggesting that in older women, the association between serum leptin levels and subsequent HAIs is mediated by nutritional status.

Leptin Functions in Infectious Diseases

Leptin, a pleiotropic protein has long been recognized to play an important role in the regulation of energy homeostasis, metabolism, neuroendocrine function, and other physiological functions through its effects on the central nervous system (CNS) and peripheral tissues. Leptin is secreted by adipose tissue and encoded by the obese (ob) gene. Leptin acts as a central mediator which regulates immunity as well as nutrition. Importantly, leptin can modulate both innate and adaptive immune responses. Leptin deficiency/resistance is associated with dysregulation of cytokine production, increased susceptibility toward infectious diseases, autoimmune disorders, malnutrition and inflammatory responses. Malnutrition induces a state of immunodeficiency and an inclination to death from communicable diseases. Infectious diseases are the disease of poor who invariably suffer from malnutrition that could result from reduced serum leptin levels. Thus, leptin has been placed at the center of many interrelated functions in various pathogenic conditions, such as bacterial, viruses and parasitic infections. We review herein, the recent advances on the role of leptin in malnutrition in pathogenesis of infectious diseases with a particular emphasis on parasitic diseases such as Leishmaniasis, Trypanosomiasis, Amoebiasis, and Malaria.

Limited utility of adipokine levels in the diagnosis of malnutrition in the elderly

BACKGROUND AND AIMS

Adipokine levels may have a role in the diagnostic and prognostic evaluation of malnutrition. The aim of the present study was to evaluate the correlation between malnutrition score and leptin, other biological markers, and body mass index (BMI) in the diagnosis of malnutrition in the elderly.

METHODS

In this cross-sectional observational study, we enrolled subjects over 70 years. Exclusion criteria were diabetes mellitus, obvious thyroid disorders, significant edema, renal dysfunction, chronic liver disease, symptomatic cardiovascular diseases, and malignity. Patients' demographic and medical data were recorded and anthropometric measurements were performed. Laboratory parameters including leptin, IGF-1, IGFBP-3, IL-6, TNF-α were measured. We defined malnutrition according to mini nutritional assessment (MNA) scale. Patients were divided into four groups according to BMI quartiles.

RESULTS

Average age of the patients was 81.9 ± 4.8 years, 68.2 % female and 31.8 % male. According to their MNA scores, 103 (66.9 %) were well nourished, 33 (21.4 %) were under malnutrition risk and 18 (11.7 %) were malnourished. MNA total and screening scores were positively correlated with albumin, BMI, high-density lipoprotein cholesterol and estimated glomerular filtration rate. Serum leptin levels (ng/ml) were 18.9 ± 22.6, 22.3 ± 21.9, 51.9 ± 85.5, and 61.7 ± 56.1 in BMI groups 1-4, respectively. BMI was positively correlated with leptin and triglyceride levels. Leptin levels were similar among nutritional state groups. Neither BMI nor MNA scores had any significant correlation with adiponectin, ghrelin, IGF-1, or IGFBP-3.

CONCLUSIONS

Adipokine levels do not seem to give relevant information in nutritional state assessment.

Leptin as an immunomodulator

Leptin is an adipocyte-derived hormone/cytokine that links nutritional status with neuroendocrine and immune functions. In humans, leptin influences energy homeostasis and regulates neuroendocrine function primarily in states of energy deficiency. Initially described as an antiobesity hormone, leptin has subsequently been shown also to influence basal metabolism, hematopoiesis, thermogenesis, reproduction, and angiogenesis. As a cytokine, leptin can affect thymic homeostasis and the secretion of acute-phase reactants such as interleukin-1 (IL-1) and tumor-necrosis factor-alpha (TNF-α). Leptin links nutritional status and proinflammatory T helper 1 (Th1) immune responses and the decrease in leptin plasma concentration during food deprivation leads to impaired immune function. Similar to other pro-inflammatory cytokines, leptin promotes Th1-cell differentiation and can modulate the onset and progression of autoimmune responses in several animal models of disease. Here, we review the advances and controversy for a role of leptin in the pathophysiology of immune responses and discuss novel possible therapeutic implications for leptin modulators.

Leptin is better than any other biological parameter for monitoring the efficacy of renutrition in hospitalized malnourished elderly patients

OBJECTIVE

Despite malnutrition being a major problem in hospitalized elderly patients, there is a lack of studies focusing on the comparative value of biological parameters for monitoring renutrition. The aim of this study was to determine which biological parameter(s) could best monitor successful renutrition in hospitalized malnourished elderly patients.

DESIGN

The objective of the study was to explore the impact of a 6-week renutrition process on anthropometric and biological parameters in elderly patients and to define the biological parameters associated with weight regain.

PATIENTS

A total of 72 hospitalized malnourished elderly patients admitted to a hospital-based geriatric rehabilitation unit.

MEASUREMENTS

Patients were evaluated at admission and at 6 weeks for anthropometric measurements of weight, sum of the four subcutaneous skinfold thicknesses, calf circumference and biological serum parameters including albumin, transthyretin, leptin, IGF-1, IGFBP-1 and IGFBP-3. Renutrition was considered successful if a patient gained at least 5% of body weight over 6 weeks.

RESULTS

Leptin was the only biological parameter that increased at 6 weeks in successful renutrition. Leptin variations were not influenced by C-reactive protein variations, in contrast to transthyretin which can be modified by the inflammatory states frequently encountered in geriatric patients.

CONCLUSIONS

Serum leptin is a more appropriate parameter than transthyretin for monitoring renutrition.

Assessment of nutritional status and serum leptin in children with inflammatory bowel disease

OBJECTIVES

Children with inflammatory bowel disease (IBD) commonly have altered nutrition and growth. Measurement of serum leptin may enhance other modalities to assess the nutritional state of children with IBD. The aim of the present study was to define the nutritional status of children with newly diagnosed IBD by measuring anthropometry and serum leptin levels.

PATIENTS AND METHODS

Twenty-eight children newly diagnosed with IBD and 56 age- and sex-matched controls were enrolled prospectively. Anthropometry (weight, height, and body mass index [BMI] expressed as z scores) and serum leptin levels were measured.

RESULTS

The children with IBD had lower mean BMI z scores and weight-for-age percentiles than controls (P = 0.05 and P = 0.01, respectively). The mean (standard deviation) serum leptin levels of the children with IBD were 2.4 (± 1.9) pg/mL, compared with 5.2 (± 4.6) pg/mL for controls (P = 0.01). The BMI percentile correlated positively with leptin levels in both groups. Following adjustment for BMI percentiles, serum leptin levels were lower in children with IBD than in controls (P = 0.02). Leptin levels did not correlate with serum markers of inflammation or disease activity scores.

CONCLUSIONS

Detailed and focused nutritional assessment should be an integral part of the management of all children with IBD. Children at the time of diagnosis of IBD have significant undernutrition and have lower serum leptin levels than controls. The inflammatory state in IBD appears not to alter leptin metabolism. Further study of the effect of leptin in IBD is required.

Low serum leptin serves as a biomarker of malnutrition in elderly patients

Anthropometric and classical biologic markers of malnutrition, such as serum albumin, are limited because they are influenced by nonnutritional factors. We propose that a biologic parameter that both predicts nutritional status and is unaffected by nonnutritional factors would facilitate the diagnosis of malnutrition in the elderly. This cross-sectional study included 179 randomized elderly patients. Nutritional status was assessed by the Mini-Nutritional Assessment (MNA) instrument; other end points included anthropometric measures and biologic parameters. Subjects were divided into 3 groups based on MNA-defined nutritional status, and end point means were compared using 2-way analyses of variance adjusted by sex. Correlations between the most accurate biologic marker in predicting malnutrition and other biologic and clinical variables were assessed using Pearson correlation test. Multiple linear regressions were then performed to relate the best biomarker of malnutrition to specific parameters. Finally, leptin levels that predict malnutrition were determined using receiver operating characteristic curve cutoff values. The well-nourished group had significantly higher leptin (P = .001), weight, body mass index, mid-arm circumference, and calf circumference (all, P < .001) compared with the malnourished group and the at risk of malnutrition group. Serum leptin was the optimal biomarker of MNA-defined malnutrition and had significant positive correlations with weight (P = .003) and with all anthropometric values (all P < .001), but no significant correlation with C-reactive protein. Sex, weight, and triglyceride were the best predictors of serum leptin (all P < .001). The optimal cutoff value of serum leptin to detect malnutrition was 4.3 ng/mL in men and 25.7 ng/mL in women. Serum leptin may be a good predictor of nutritional status in elderly patients.

Nutrition, inflammation, and leptin levels in aging and frailty

OBJECTIVES

To examine nutritional indices and levels of leptin and inflammatory markers across age and frailty.

DESIGN

Observational study.

SETTING

Continuing care wards and a day hospital in Cardiff, South Wales, United Kingdom.

PARTICIPANTS

Thirty dependent patients (mean age 84.9) needing continuing inpatient care, 40 patients with falls attending a day hospital (mean age 84.2), 40 independent controls (mean age 82.7), and 30 young controls (mean age 23.3).

MEASUREMENTS

Functional status, including the five frailty indicators proposed by Fried et al., anthropometry, and serum markers of nutrition and inflammation.

RESULTS

The continuing care patients were frail, all having three to five frailty indicators. Day hospital patients were of intermediate frailty (mean Fried score 2.97), and the independent group was fittest (0.83). Body mass index, triceps skinfold thickness (TSF), and mid-arm muscle area were lowest in continuing care patients. With increasing patient frailty, albumin levels fell significantly (P<.005) and C-reactive protein (CRP) levels increased significantly (P<.005). Continuing care patients had significantly lower leptin levels (P<.005) and significantly higher interleukin (IL)-6 levels (P<.005). There was a significant correlation between log transformed leptin and TSF for each patient group.

CONCLUSION

The frailest older people displayed features of cachexia. Their leptin levels were appropriately low given their low body fat, and IL-6 and CRP levels were high. The mechanism of their cachexia may therefore be similar to that proposed in heart failure and cancer: disturbed hypothalamic feedback of leptin or effects of proinflammatory cytokines.

Severe pulmonary metastasis in obese and diabetic mice

Although obesity is known as a risk factor for several human cancers, the association of obesity with cancer recurrence and metastasis remains to be characterized. Here, B16-BL6 melanoma and Lewis lung carcinoma cells were intravenously injected into diabetic (db/db) and obese (ob/ob) mice. The number of experimental lung colonies was markedly promoted in these mice when compared with C57BL/6 mice. In contrast, tumor growth at the implanted site was comparable when cells were inoculated orthotopically. The use of B16-BL6 cells stably transfected with the luciferase gene revealed that the increased metastasis reflected a difference mainly within 6 hr after the intravenous inoculation of tumor cells. Administration of recombinant leptin in ob/ob mice abolished the increase in metastasis early on as well as the decrease in the splenic NK cell number. In addition, depletion of NK cells by an anti-asialo-GM1 antibody abrogated the enhanced metastasis in db/db mice. These results demonstrate that metastasis is markedly promoted in diabetic and obese mice mainly because of decreased NK cell function during the early phase of metastasis.

Leptin a new biological marker for evaluating malnutrition in elderly patients

BACKGROUND

There is no single universally accepted biochemical marker of nutritional status in the elderly. Many markers are affected by non-nutritional factors.

OBJECTIVE

The purpose of this study was to determine the biological parameters best related to anthropometric markers of malnutrition in an elderly polypathological population, and determine cutoff values for these potential parameters to diagnose malnutrition.

DESIGN

This prospective study enrolled 116 elderly hospitalized patients and 76 elderly outpatients. Nutritional status (albumin, transthyretin, body mass index (BMI), skinfold thickness) and biological parameters (leptin, insulin-like growth factor-1 (IGF-1), IGF binding protein-1 (IGFBP-1), IGFBP-3, C-reactive protein (CRP), orosomucoid) were assessed. We defined malnutrition according to the lowest quartile of BMI and skinfold thickness measured in a large healthy elderly French sample population.

RESULTS

In this sample of elderly patients (age: 85+/-7 years old), leptin concentration was the only biological parameter significantly related to nutrition status. Independent correlations were found between leptin concentration and BMI, skinfold thickness and sex. The relationship between nutritional status and leptin concentration is significantly different in each sex: the more the patients are undernourished, the lower the leptin concentration in both sexes. The optimal leptin cutoff value for the diagnosis of malnutrition in this population was 4 microg/l in men (sensitivity 0.89, specificity 0.82) and 6.48 microg/l in women (sensitivity 0.90, specificity 0.83).

CONCLUSION

Leptin concentration is highly correlated with anthropometric data whereas albumin or transthyretin are known to be also influenced by morbidity and inflammatory conditions. Serum leptin concentration could be used for nutritional assessment in elderly patients with acute diseases.

Serum leptin concentrations in children with mild protein-energy malnutrition and catch-up growth

BACKGROUND

The aim of the present study was to clarify the relationship between changing nutritional anthropometric data and serum leptin concentrations during the catch-up growth process in children.

METHODS

Thirty children with mild protein-energy malnutrition (PEM) were followed for 6 months and their anthropometric measurements and serum leptin concentrations were recorded during follow up.

RESULTS

Twenty-two (73.3%) of the 30 children showed catch-up growth. All parameters and serum leptin concentrations increased during the period of catch-up growth. In the remaining eight children, weight for height, percentage standard body mass index, percentage standard body height and mean serum leptin concentrations did not show any significant increase at the 6 month follow-up. Mean serum leptin concentration was higher in children with catch-up growth than in the controls.

CONCLUSION

During recovery from malnutrition, leptin concentrations increase in relation to fat mass if the fat mass reaches a critical point, and leptin might trigger catch-up growth with its regulator effects on growth. Although weight gain was noted in both groups, an increase in leptin concentration was observed only in children who showed catch-up growth. More interestingly, the mean leptin concentration was much higher in children with PEM who had catch-up growth compared to the control group and in children who failed to have catch-up growth. In children with catch-up growth, the higher serum leptin concentrations compared to healthy children and to children without catch-up growth despite significant weight gain suggests that leptin affects nutritional status in catch-up growth as a dynamic process, rather than merely being an index of body fat content.

Serum leptin concentrations in children with mild-to-moderate protein-energy malnutrition

BACKGROUND

The aim of the present study was to clarify the relationship between nutritional anthropometric parameters and serum leptin concentrations in otherwise healthy children with mild-to-moderate protein-energy malnutrition (PEM) secondary to inadequate energy intake.

METHODS

Eighty-one otherwise healthy children with poor appetite and inadequate energy intake were enrolled in the study. The anthropometric values were evaluated in all subjects. Fasting serum leptin concentrations were assessed.

RESULTS

Of the 81 otherwise healthy children, 30 were found to have mild-to-moderate PEM. The control group consisted of 51 healthy children who had normal anthropometric values, even though they had inadequate energy intake. There was a significant difference in serum leptin concentrations between the two groups (P < 0.01). Furthermore, there was a positive correlation between mean serum leptin concentrations and percentage of standard weight for height in the patient and the control group (P < 0.05). Multiple linear regression analysis indicated that percentage of standard BMI was the best predictor for serum leptin concentrations (P < 0.05).

CONCLUSION

In addition to BMI, percentage of standard weight for height is a valuable nutritional anthropometric parameter for serum leptin concentrations in PEM and inadequate energy intake. However in the present study, percentage of standard BMI was the best predictor for serum leptin concentrations. Serum leptin concentrations are low not only in severe PEM, but also in children with mild-to-moderate PEM without chronic disease.

Leptin prevents the fall in plasma osteocalcin during starvation in male mice

Plasma osteocalcin, a marker of osteoblastic activity, is reduced in starvation, malnutrition, and anorexia nervosa, resulting in low bone turnover osteoporosis. Contradictory findings about the role of leptin as a link between nutritional status and bone physiology have been reported. We demonstrate that leptin-deficient ob/ob and leptin-resistant db/db male mice have increased plasma osteocalcin, and that in male ob/ob mice osteocalcin is not decreased by starvation, unlike control mice. Intraperitoneal leptin administration increased plasma osteocalcin in male ob/ob mice, and prevented its fall during 24h fasting and 5 days of food restriction in normal male mice. This effect may be mediated via actions on the hypothalamic-pituitary-testicular or -growth hormone axes, or a direct action on osteoblasts. These studies support the hypothesis that the fall in leptin during starvation and weight loss is responsible for the associated reduction in osteoblast activity, and suggest a role for leptin in regulating bone turnover.

Patterns of plasma leptin and insulin concentrations in hospitalized patients after the initiation of total parenteral nutrition

BACKGROUND

The regulation of leptin in patients with critical illness is poorly understood. Sex, diet, body mass, and cytokines may all play a role.

OBJECTIVE

The aims of this study were to determine the factors influencing leptin concentrations in hospitalized patients beginning total parenteral nutrition (TPN) and whether a 3-d regimen of TPN would further increase plasma leptin concentrations above baseline.

DESIGN

Twenty-six patients requiring TPN were enrolled in this prospective, nonintervention study. Only 20 (11 women and 9 men) completed all 3 d of TPN.

RESULTS

Baseline plasma leptin in the TPN patients ranged from 62.5 to 1625 pmol/L ( +/- SD: 419 +/- 387; n = 26) and was not significantly different between men (444 +/- 494 pmol/L) and women (363 +/- 244 pmol/L). Baseline plasma insulin ranged from 76 to 695 pmol/L (271 +/- 188; n = 26) and was not correlated with plasma leptin. Leptin concentrations increased after 3 d of TPN, from 356 +/- 300 to 794 +/- 600 pmol/L (P < 0.05) in parallel with an increase in insulin from 257 +/- 187 to 979 +/- 917 pmol/L (P < 0.01) in the 20 patients who completed the study; however, the changes were not correlated when expressed as percentages. Although the men and women had insulin responses to feeding that were not significantly different, leptin concentrations did not increase significantly in men but increased 3-fold in women (to 1094 +/- 638 pmol/L; P < 0.01).

CONCLUSIONS

Leptin regulation in patients with a critical illness differs substantially from that in healthy persons. The importance of glucose and insulin in leptin secretion remains unclear, especially in men.

Serum leptin levels in alcoholic liver cirrhosis: relationship with gender, nutritional status, liver function and energy metabolism

OBJECTIVE

To determine serum leptin levels in alcoholic liver cirrhosis and the relationship with gender, nutritional status, liver function, energy metabolism, inflammatory state and refeeding.

SUBJECTS

Thirty-seven hospitalized alcoholic cirrhotic patients (M/F: 24/13), 27 hospitalized patients at risk of malnutrition but with normal liver function (M/F: 15/12) as control patients, and 31 healthy control subjects (M/F: 17/14) participated.

DESIGN

Liver function was assessed from Child-Pugh classification; anthropometric parameters and resting energy expenditure (REE) were measured; caloric intake was evaluated over 5 days; and serum leptin and insulin were assayed. The same protocol was performed after 1 month refeeding in 22 patients. Healthy subjects were studied as controls for anthropometric parameters and serum leptin levels.

RESULTS

Serum leptin levels were higher in male cirrhotic patients than in the other two male groups (P=0.0079) and in the same range in the female groups. They were higher in female than in male subjects in the three groups. In female cirrhotic patients, logarithmically transformed serum leptin levels correlated significantly with fat mass (P=0.0043), insulin levels (P=0.0072), REE (P=0.0133), bilirubin levels (P<0.0001), prothrombin time (P=0.0003) and Pugh score (P=0.0266) in simple regression analysis and with insulin levels (P=0.0137), but not with fat mass (P=0.0761), Pugh score (P=0.4472) and REE (P=0.4576) in multiple regression analysis. In the male cirrhotic and control patients, log (leptin) levels correlated with CRP (C reactive protein) (r=0.365, P=0.0223). Log (leptin) levels did not correlate with caloric intake in any of the groups. Leptin levels (P<0.05) and fat mass (P<0.02) increased with refeeding while liver function improved (P<0.01).

CONCLUSION

There is a gender difference in regulation of serum leptin level in alcoholic liver cirrhosis. Insulin level is the best determinant of leptin level in female patients while inflammatory state related to alcoholic hepatitis seems to have a greater influence in male patients. Although leptin levels positively correlated with REE in female patients, there is no evidence that leptin reduces caloric intake and fat stores in these patients.

Serum leptin levels in patients with viral chronic hepatitis or liver cirrhosis

BACKGROUND/AIM

Serum levels of leptin, the adipocyte-derived hormone regulating food intake and energy expenditure in mammals, have been found to be increased in cirrhotic patients. The aim of the present study was to investigate leptin serum level in relation to anthropometric features and liver function in patients with viral chronic hepatitis or liver cirrhosis.

METHODS

Serum leptin levels were determined by radioimmunoassay in 30 male and 10 female patients with chronic hepatitis, in 42 male and 10 female patients with liver cirrhosis, and in four respective control groups. Liver function was evaluated by the monoethylglycinexylidide formation test. Body mass index and body fat mass were estimated by weight, height and skinfold thickness measurements.

RESULTS

Compared with controls, absolute serum leptin levels were significantly (p<0.01) lower in chronic hepatitis patients and similar in cirrhotic patients. Leptin serum levels were significantly (p<0.05) higher in cirrhotic than in chronic hepatitis patients. When expressed in relation to body fat mass, the above differences persisted; however, cirrhotic females showed significantly (p<0.05) higher serum leptin values than controls. Serum leptin values correlated negatively (p<0.01) with monoethylglycinexylidide serum values in all groups of patients.

CONCLUSIONS

In patients with chronic viral liver disease, serum leptin levels tend to increase as liver function worsens. This may reflect a decline in the ability to downregulate energy expenditure as an adaptation to anorexia and/or to defective substrate utilisation due to liver disease and may negatively influence body weight homeostasis in these patients.

Impaired leukotriene C4 generation in granulocytes from protein-energy malnourished chronically ill elderly

OBJECTIVE

The dysregulation of the immune and inflammatory systems observed in protein-energy malnutrition (PEM) may be partly due to perturbation of essential fatty acid metabolism. In this study, we assessed the calcium ionophore A23187-induced generation of the arachidonate metabolites leukotriene B4 (LTB4) and leukotriene C4 (LTC4) in isolated granulocyte suspensions.

DESIGN

Case-control study.

SETTING

A university-affiliated acute care hospital in urban Stockholm.

SUBJECTS

Fourteen severely malnourished elderly subjects with stable non-malignant disorders (age 74 +/- 1 years, mean +/- SEM) and 12 healthy age-matched controls were examined.

MAIN OUTCOME MEASURES

Leukotrienes were analysed by high-performance liquid chromatography. Body mass index (BMI, kg m-2) and delayed cutaneous hypersensitivity (DCH) reaction were determined.

RESULTS

BMI was 16. 5 +/- 0.5 and 26.2 +/- 0.9 kg m-2 (mean +/- SE) in the malnourished group and controls (P < 0.001), respectively. DCH was 8.5 mm (median) in patients and 29.5 mm in controls (P < 0.001). LTC4 generation in granulocytes from PEM patients was half of that of controls (9.1 +/- 2.0 vs. 17.8 +/- 5.2 pmol mL-1, P < 0.05) when cells were stimulated with 0.2 micromol L-1 of A23187, and 13.7 +/- 2.5 and 27.2 +/- 7.5 pmol mL-1, respectively (NS), upon stimulation with 1.0 micromol L-1 of A23187. LTB4 production in PEM patients and controls did not differ at any of the two calcium ionophore concentrations. LTC4 production correlated with BMI (r = 0.41, P < 0.05), but there was no significant correlation between DCH and LTB4 or LTC4 production.

CONCLUSION

Protein-energy malnutrition is accompanied by perturbation of leukotriene synthesis, which may be one factor underlying the dysregulation of inflammatory responses in the depleted patient.

Serum leptin levels in diabetic patients on hemodialysis: the relationship to parameters of diabetes metabolic control

Leptin is a protein hormone produced predominantly by adipocytes that affects food intake and energy expenditure. Its serum levels are significantly higher in patients with chronic renal failure compared to healthy subjects. The aim of this study was to compare serum leptin levels in hemodialyzed patients with type II diabetes mellitus (n=26) with body content-matched hemodialyzed patients without diabetes (n=26) and to explore the relationship between parameters of the long term diabetes metabolic control and serum leptin levels. Serum leptin levels in diabetic patients did not significantly differ from those of non-diabetic patients (25.3+/-8.8 vs 25.7+/-8.7 ng/ml). Serum leptin levels in diabetic patients positively correlated with body fat content, body mass index and predialysis serum insulin levels. No significant relationship were observed between serum leptin levels and blood glucose, glycated hemoglobin, glycated protein, serum urea, creatinine, leukocyte count and total hemoglobin respectively. The multiple stepwise regression analysis revealed that body fat content together with body mass index accounted for 77.8% of variations in predialysis serum leptin levels, while insulin levels and the parameters of diabetes metabolic control had only slight prediction value for leptin concentrations. We conclude that serum leptin levels in hemodialysed patients with type III diabetes mellitus do not significantly differ from those of hemodialysed non-diabetic patients. The body fat content and body mass index are the strongest predictors of serum leptin levels, while parameters of long term diabetes metabolic control play probably only minor direct role in its regulation.

Physiological roles of the leptin endocrine system: differences between mice and humans

Leptin is a 16-kDa cytokine secreted in humans primarily but not exclusively by adipose tissues. Its concentration in blood is usually proportional to body fat mass, but is higher in women than in men not only because of a different distribution of and greater fat mass in women, but also because testosterone reduces its level in men. Leptin features in different ways during the life span. It is synthesized in the ovary, transported in the oocyte, and made by both fetus and placenta, particularly during the last month of gestation. It is made by the lactating mammary gland and ingested by the newborn infant in its milk. The prime importance of leptin is realized at puberty when it is necessary for progression to a normal adult reproductive status in females. Fasting and chronic undernutrition result in a lower level of leptin in the blood. Lack of leptin results in hunger, ensuring that the individual eat to survive, and also inhibition of reproduction, until such time as food and fat stores are adequate to supply energy for pregnancy and lactation. Thus, leptin is important for survival of the individual and survival of the species. Although an extremely rare genetic absence of leptin induces hyperphagia and obesity in humans, as it does in mice, there appears to be little role for leptin in humans in ensuring that fat stores are not in excess of adequate, that is, in preventing obesity. The mouse differs from humans in many respects, in particular in the far more drastic ways it conserves energy when it very rapidly adapts to lack of food. These include not only suppression of reproduction but also lowering of its body temperature (torpor), suppressing its thyroid function, suppressing its growth, and increasing secretion of stress hormones (from the adrenal). This review concentrates on roles of leptin in human physiology and pathophysiology but also discusses why some observations on actions of leptin in mice are not applicable to humans.

Relationship of serum leptin levels and selected nutritional parameters in patients with protein-caloric malnutrition

Leptin is a protein hormone produced by adipocytes that reflects the body fat content, i.e., its serum concentration in healthy individuals positively correlates with the body mass index and body fat content. Serum leptin levels are lower in both patients with anorexia nervosa and protein-caloric malnutrition caused by chronic non-malignant illnesses. The aim of the present study was to compare serum leptin levels and selected, routinely used nutritional parameters in women with anorexia nervosa (n = 17), severely malnourished patients with short bowel syndrome (n = 13), and control non-obese healthy women (n = 17) to clarify the relation between selected nutritional parameters and serum leptin levels. We found that serum leptin levels in the anorexia nervosa and short bowel syndrome groups were significantly lower than those in the control group (in ng/mL: 3.63 +/- 1.64 and 2.59 +/- 1.17 versus 12.06 +/- 7.59, respectively). Protein malnutrition expressed by decrease in serum concentrations of total protein, albumin, and prealbumin was more pronounced in the short bowel syndrome group. Triceps skin fold, arm muscle circumference, and body mass index were significantly lower in the patient group than in the control group and did not significantly differ between the short bowel syndrome and anorexia nervosa groups. No significant difference in serum leptin concentration between the short bowel syndrome and anorexia nervosa groups was found. Serum leptin levels correlated positively with body mass index and triceps skin fold in the control and anorexia nervosa groups but not in the short bowel syndrome group. We conclude that serum leptin levels in patients with anorexia nervosa and short bowel syndrome are significantly lower than in healthy individuals and have no statistically significant relation to serum total protein, abumin, and prealbumin.

The relationship of serum leptin levels and parameters of endurance training status in top sportsmen

Leptin is a hormone that reflects the body fat content. It was reported that serum leptin levels were decreased in highly endurance-trained sportsmen in comparison with control non-sporting subjects. The aim of our work was to study the relation of serum leptin to blood viscosity and selected spiroergometric parameters of endurance capacity in a group of top rugby players and top race walkers. We have found that both body fat content and serum leptin levels were significantly lower in race walkers than in rugby players (9.68+/-3.65 vs 15.95+/-3.15% and 2.84+/-1.1 vs 3.89+/-1.09 ng x ml(-1) respectively, p<0.05). The positive correlation of serum leptin levels with body fat in both groups. The level of endurance training status was significantly higher in the race walkers group. Serum leptin levels significantly negatively correlated oxygen uptake per body and pulse oxygen per body weight only in rugby players but not in race walkers. Partial correlation test after adjusting for the effect of body fat content showed that leptin itself is not an independent predictor of endurance trainability in this group. Serum leptin levels correlated positively with blood viscosity only in race walkers, but not in the rugby players group. We conclude that serum leptin levels in top sportsmen parallel the changes in body fat content and are not an independent predictor of endurance training of these subjects.

Geriatric cachexia: the role of cytokines

Weight loss in elderly patients is a common clinical problem. Wasting and cachexia are associated with severe physiologic, psychologic, and immunologic consequences, regardless of the underlying causes. Cachexia has been associated with infections, decubitus ulcers, and even death. Multivariate analyses of risk and prognostic factors in community-acquired pneumonia in the elderly have found that age by itself is not a significant factor related to prognosis. Among the significant risk factors, only nutritional status is amenable to medical intervention. Cachexia in the elderly may have profound consequences: medical, cognitive, and psychiatric disorders may diminish self-reliance in activities of daily living, thus reducing quality of life and increasing the frequency of secondary procedures, hospitalizations, and the need for skilled care. Cachexia is associated with higher-than-normal concentrations of tumor necrosis factor alpha (TNF-alpha), interleukin (IL) 1, IL-6, serotonin, and interferon gamma. The role of these proinflammatory cytokines has been established in the cachexia seen in cancer and AIDS patients. Reduction in the concentrations of these cytokines is associated with weight gain. Drugs that promote appetite stimulation and weight gain, such as progestational agents, cyproheptadines, pentoxifylline, and thalidomide may work by down-regulating these proinflammatory cytokines. An understanding of the relation between cachexia and negative regulatory cytokines may point to effective treatment of geriatric cachexia as well.

[Pathophysiology of catabolism in undernurished elderly patients]

Malnutrition is a common finding amongst our elders. The causes of malnutrition are multifactorial and although they have been extensively studied, they are not entirely understood. Both physiological and pathological processes of aging put this population at a higher risk of being undernourished. These may be related to social, financial, psychological and/or physiological changes directly or indirectly associated to growing old. Age associated changes increase the risk of malnutrition in older individuals. These alterations range from problems in taste and smell perception, which were previously thought to be the main cause of anorexia in this population, to alterations in either the concentration or efficacy of the previously mentioned feeding modulators. Increased intestinal malabsorption together with an altered pancreatic exocrine response to different diets, further contributing to subclinical malabsorption in the elderly population aged and may account in part for the malnutrition observed in this group. Although not directly caused by the aging process, several conditions such as anorexia nervosa, cancer, infectious conditions, and inflammatory processes are associated with decreased food intake and weight loss. These conditions present with elevated levels of immunoregulatory substances known as cytokines. Each of these cytokines has multiple effects and play a leading role in the pathophysiology and maintainance of malnutrition in these situations.

The role of nutrition in prevention and healing of pressure ulcers

Among the many risk factors for pressure ulcers, malnutrition is potentially reversible. This article examines the relationship of malnutrition to the prevention and healing of pressure ulcers. Evidence for nutrition in preventing and healing pressure ulcers is presented. Specific nutrients, including some amino acids, vitamins, and minerals, have been evaluated for their effects on wound healing.