Cardiometabolic comorbidities and complications of obesity and chronic kidney disease (CKD)

Obesity and chronic kidney disease are two ongoing progressive clinical pandemics of major public health and clinical care significance. Because of their growing prevalence, chronic indolent course and consequent complications both these conditions place significant burden on the health care delivery system especially in developed countries like the United States. Beyond the chance coexistence of both of these conditions in the same patient based on high prevalence it is now apparent that obesity is associated with and likely has a direct causal role in the onset, progression and severity of chronic kidney disease. The causes and underlying pathophysiology of this are myriad, complicated and multi-faceted. In this review, continuing the theme of this special edition of the journal on " The Cross roads between Endocrinology and Nephrology" we review the epidemiology of obesity related chronic kidney disease (ORCKD), and its various underlying causes and pathophysiology. In addition, we delve into the consequent comorbidities and complications associated with ORCKD with particular emphasis on the cardio metabolic consequences and then review the current body of evidence for available strategies for chronic kidney disease modulation in ORCKD as well as the potential unique role of weight reduction and management strategies in its improvement and risk reduction.

Nonclassic Congenital Adrenal Hyperplasia Metabolic Resolution Post Roux-en-Y Gastric Bypass and Associated Weight Loss

Nonclassic congenital adrenal hyperplasia (NCCAH) is characterized by mild cortisol deficiency, excess androgens and adrenocorticotropin (ACTH) production, and often with various features of dysmetabolic syndrome. Elective bariatric surgery is one of the most effective long-term management strategies for severe obesity. Our case presents a 34-year-old woman with symptomatic NCCAH and class III obesity who status post Roux-en-Y gastric bypass (RYGB) had significant weight loss with metabolic resolution of NCCAH, and no longer required glucocorticoid (GC) therapy. At 11 months post operation and off GC therapy, she had a weight deficit of approximately 160 pounds (72.57 kg) with continued metabolic resolution of NCCAH markers including ACTH, 17-hydroxyprogesterone, and androstenedione. Presently, GC therapy remains one of the few available treatments for symptomatic NCCAH; however, long-term GC therapy has the potential for various complications and side effects. Our case presents elective bariatric surgery as a potential and unique treatment option for patients with NCCAH with associated class III obesity. The exact pathophysiologic basis for this effect and its potential role in long-term management of appropriate NCCAH patients requires further study.

Abstract P142: Mediation of Effects of a Low-Carbohydrate Dietary Intervention on Hemoglobin A1c Through Weight: A Randomized Clinical Trial

Introduction: Low-carbohydrate diets lead to weight loss and improvement in hemoglobin A1c and other cardiometabolic outcomes. However, there is limited research on how much of the glycemic effects of low-carbohydrate diets are mediated by weight loss.

Hypothesis: The effect of a low-carbohydrate dietary intervention on hemoglobin A1c would be mediated by weight loss.

Methods: We conducted a 6-month randomized clinical trial on the effects of a low-carbohydrate diet intervention (target <40 net grams of carbohydrates during first 3 months; <60 net grams for months 3-6) compared with usual diet on hemoglobin A1c. Participants were 40-70 years with untreated HbA1c of 6.0-6.9%. In post hoc mediation analyses, we examined whether the effect of the intervention on 6-month change in hemoglobin A1c was mediated by 3-month weight, after adjustment for age, sex, race, education, and baseline levels of behavioral and cardiometabolic risk factors. We used the causal framework approach described by and the SAS macro developed by Valeri and VanderWeele.

Results: 150 participants (mean [SD] age 59 [8] years; 108 [72%] female; 88 [59%] Black) were randomized to either the low-carbohydrate diet intervention (75 participants) or usual diet (75 participants) arm. Mean (SD) HbA1c was 6.16% (0.30%) at baseline. Six-month data was collected on 142 participants (95%). Compared with the usual diet arm, the low-carbohydrate diet intervention arm had significantly greater 6-month reduction in HbA1c (net difference, -0.23% [95% CI, -0.32 to -0.14%]) and body weight (-5.9 kg [95% CI, -7.4 to -4.4 kg]). In mediation analyses, 59% of the total effect of intervention on 6-month change in hemoglobin A1c was mediated by weight measured at 3 months (Table).

Conclusions: In mediation analyses, a substantial proportion (59%) of the total effect of intervention on 6-month change in hemoglobin A1c was mediated through weight measured at 3 months. Future research should further explore contributions of weight loss to reductions in glycemia in other populations.

Abstract 20: Effect of Dietary Sodium Reduction in Chronic Kidney Disease Patients With Albuminuria: Results of a Randomized Trial

Introduction: Albuminuria, an early marker of kidney damage, is a risk factor for chronic kidney disease (CKD) progression, cardiovascular disease (CVD), and death. Dietary sodium is a risk factor for elevated blood pressure, CVD, and all cause-mortality. It is particularly important in patients with CKD due to increased salt-sensitivity. It is unclear if dietary sodium reduction is associated with reduced albuminuria.

Hypothesis: A low sodium diet will reduce albuminuria in patients with CKD.

Methods: The Sodium Lowering and Urinary Protein Reduction (SUPER) Trial was a randomized, parallel trial testing the effect of a 24-week dietary sodium reduction intervention compared to usual diet on albuminuria in 151 CKD patients with albuminuria. Participants were eligible if they had an estimated glomerular filtration rate (eGFR) of 30-90 mL/min/1.73 m 2 and an albumin-to-creatinine ratio (ACR) of 30-1,500 mg/g. Intervention group participants received a dietician-led behavioral change intervention targeting sodium intake <2,300 mg/day and those in the control group received no dietary intervention. Twenty-four hour urine samples and dietary recalls, blood pressure, weight, and questionnaire data was collected at baseline, 12 weeks and 24 weeks. Mixed effects models were used to examine the intervention effect.

Results: Study participants were an average of 65.6 years old, 72% African American, and 48% women. Median baseline ACR was 180.3 mg/g in the intervention and 157.4 mg/g in the control group, respectively. Urinary sodium excretion was reduced by 15.5% and 0.0% in the intervention and control groups, respectively. Results for the primary and key secondary outcomes are presented in the Table.

Conclusions: The dietician-led dietary sodium reduction intervention succeeded in significantly reducing dietary sodium and BP in patients with CKD and albuminuria. However, no significant differences were observed in ACR, albuminuria, or eGFR between treatment groups.

Incident diabetes complications among women with type 1 diabetes based on parity

OBJECTIVES

To assess risk factors and incidence of diabetes complications in women with type 1 diabetes (T1D) based on parity.

RESEARCH DESIGN/METHODS

Data were collected from women (16-40 years old) in the T1D Exchange completing pregnancy/childbirth questionnaires during 2011-2013 and 2016-2018. Incidence of risk factors and diabetes complications were compared between women with a first pregnancy at/within 1-year of enrollment (n = 28) and never pregnant women by year 5 (n = 469).

RESULTS

There was a trend for lower HbA1c (adjusted p = .14) and higher rates of overweight/obesity, triglyceride/HDL > 2, log (triglyercide/HDL), and hypertension among parous women compared with nulliparous women. There were no significant differences in rates of advanced nephropathy, albuminuria or cardiovascular disease.

CONCLUSIONS

Four-5 years after delivery, parous women with T1D tended to have lower HbA1c levels despite higher body mass indices and more frequent adverse lipid profiles and hypertension compared with nulliparous women. Further studies based on these trends are warranted.

Effects of a Low-Carbohydrate Dietary Intervention on Hemoglobin A1c: A Randomized Clinical Trial

IMPORTANCE

Low-carbohydrate diets decrease hemoglobin A1c (HbA1c) among patients with type 2 diabetes at least as much as low-fat diets. However, evidence on the effects of low-carbohydrate diets on HbA1c among individuals with HbA1c in the range of prediabetes to diabetes not treated by diabetes medications is limited.

OBJECTIVE

To study the effect of a behavioral intervention promoting a low-carbohydrate diet compared with usual diet on 6-month changes in HbA1c among individuals with elevated untreated HbA1c.

DESIGN, SETTING, AND PARTICIPANTS

This 6-month randomized clinical trial with 2 parallel groups was conducted from September 2018 to June 2021 at an academic medical center in New Orleans, Louisiana. Laboratory analysts were blinded to assignment. Participants were aged 40 to 70 years with untreated HbA1c of 6.0% to 6.9% (42-52 mmol/mol). Data analysis was performed from November 2021 to September 2022.

INTERVENTIONS

Participants were randomized to a low-carbohydrate diet intervention (target <40 net grams of carbohydrates during the first 3 months; <60 net grams for months 3 to 6) or usual diet. The low-carbohydrate diet group received dietary counseling.

MAIN OUTCOMES AND MEASURES

Six-month change in HbA1c was the primary outcome. Outcomes were measured at 0, 3, and 6 months.

RESULTS

Of 2722 prescreened participants, 962 underwent screening, and 150 were enrolled (mean [SD] age, 58.9 [7.9] years; 108 women [72%]; 88 Black participants [59%]) and randomized to either the low-carbohydrate diet intervention (75 participants) or usual diet (75 participants) group. Six-month data were collected on 142 participants (95%). Mean (SD) HbA1c was 6.16% (0.30%) at baseline. Compared with the usual diet group, the low-carbohydrate diet intervention group had significantly greater 6-month reductions in HbA1c (net difference, -0.23%; 95% CI, -0.32% to -0.14%; P < .001), fasting plasma glucose (-10.3 mg/dL; 95% CI, -15.6 to -4.9 mg/dL; P < .001), and body weight (-5.9 kg; 95% CI, -7.4 to -4.4 kg; P < .001).

CONCLUSIONS AND RELEVANCE

In this randomized clinical trial, a low-carbohydrate dietary intervention led to improvements in glycemia in individuals with elevated HbA1c not taking glucose-lowering medication, but the study was unable to evaluate its effects independently of weight loss. This diet, if sustained, might be a useful dietary approach for preventing and treating type 2 diabetes, but more research is needed.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03675360.

Real-World Management of Hyperkalemia in the Emergency Department: An Electronic Medical Record Analysis

Introduction

Hyperkalemia is often managed in the emergency department (ED) and it is important to understand how ED management and post-discharge outcomes vary by hyperkalemia severity. This study was conducted to characterize ED management and post-discharge outcomes across hyperkalemia severities.

Methods

Adults with an ED visit with hyperkalemia (at least one serum potassium lab measure above 5.0 mEq/L) were selected from US electronic medical record data (2012–2018). Patient characteristics, potassium levels, treatments, and monitoring prior to and during the ED visit were compared by hyperkalemia severity (mild [> 5.0–5.5 mEq/L], moderate [> 5.5–6.0], severe [> 6.0]) using unadjusted analyses. Death, immediate inpatient admission, 30-day hyperkalemia recurrence, and 30-day inpatient admission were also assessed by severity.

Results

Of 6222 patients included, 4432 (71.2%) had mild hyperkalemia, 1085 (17.4%) had moderate, and 705 (11.3%) had severe hyperkalemia. Chronic kidney disease (39.9–50.1%) and heart failure (21.6–24.3%) were common. In the ED, electrocardiograms (mild, 56.5%; moderate, 69.6%; severe, 81.0%) and patients with at least two potassium laboratory values increased with severity (15.0%; 40.4%; 75.5%). Among patients with at least two potassium laboratory values, over half of patients (60.4%) had potassium levels ≤ 5.0 mEq/L prior to discharge. Use of potassium-binding treatments (sodium polystyrene sulfonate: mild = 4.1%; moderate = 17.1%; severe = 27.4%), temporizing agents (5.6%; 15.5%; 31.6%), or dialysis (0.4%; 0.8%; 3.0%) increased with severity; treatment at discharge was not common. Death (1.1%; 3.7%; 10.6%), immediate admission to inpatient care (5.8%; 8.7%; 12.7%), 30-day hyperkalemia recurrence (2.9%; 19.0%; 32.5%), 30-day inpatient admission with hyperkalemia (6.5%; 7.9%; 9.3%) also increased with severity.

Conclusion

Patients with moderate and severe hyperkalemia experienced elevated risk of hyperkalemia recurrence and hyperkalemia-related inpatient readmission following discharge from the ED from a descriptive analysis. Future research to assess strategies to reduce hyperkalemia recurrence and inpatient admission in this patient population would be beneficial.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-021-02017-w.

Determinants of Hyperkalemia Progression Among Patients with Mild Hyperkalemia

Introduction

The progression of mild hyperkalemia and the predictors of progression have not been well characterized. In this study we aimed to characterize the progression of hyperkalemia and identify the risk factors for hyperkalemia progression.

Methods

Adults with mild hyperkalemia (at least one serum potassium measure > 5.0 and ≤ 5.5 mEq/L) were identified using electronic medical records from the Research Action for Health Network (2012–2018). Progression to moderate-to-severe and progression to severe hyperkalemia were defined as the first occurrences of a serum potassium measure > 5.5 and > 6.0 mEq/L, respectively. Kaplan–Meier analyses were conducted to estimate progression rates for all patients and by pre-specified patient subgroups. Hazard ratios (HR) of moderate-to-severe and severe hyperkalemia progression were estimated using Cox models.

Results

Of 35,369 patients with mild hyperkalemia, 16.9% and 8.7% progressed to moderate-to-severe and severe hyperkalemia, respectively. Rates of hyperkalemia progression elevated with the severity of chronic kidney disease (CKD). The highest progression rates were seen in patients with CKD stage 5 (stage 5 vs. no CKD: moderate-to-severe, 50.2% vs. 12.0%; severe, 31.3% vs. 3.9%; p < 0.001). Higher progression rates were also observed in patients with heart failure, hypertension, and type II diabetes compared with patients without those conditions (all p < 0.001). The most prominent risk factors were CKD stage 5 (HR of progression to moderate-to-severe hyperkalemia, 3.32 [95% CI 3.03–3.64]; severe, 4.08 [3.55–4.69]), CKD stage 4 (2.19 [1.97–2.43], 2.28 [1.92–2.71]), CKD stage 3 (1.57 [1.46–1.68], 1.65 [1.46–1.87]), type I diabetes (1.37 [1.18–1.61], 1.54 [1.23–1.93]), and serum potassium (1.12 [1.10–1.15], 1.13 [1.10–1.17] per 0.1 mEq/L increase) (all p values < 0.05).

Conclusion

Hyperkalemia progression rates increased significantly with CKD stage and were also higher among patients with higher baseline potassium level, heart failure, hypertension, and diabetes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-021-01925-1.

Changes in Device Uptake and Glycemic Control Among Pregnant Women With Type 1 Diabetes: Data From the T1D Exchange

OBJECTIVES

To examine changes in device use and glycemic outcomes for pregnant women from the T1D Exchange Clinic Registry between the years 2010-2013 and 2016-2018.

METHODS

Participant-reported device use and glycemic outcomes were compared for women aged 16-40 years who were pregnant at the time of survey completion, comparing 2010-2013 (cohort 1) and 2016-2018 (cohort 2). Hemoglobin A1c results within 30 days prior to survey completion were obtained from medical records.

RESULTS

There were 208 pregnant women out of 5,236 eligible participants completing the questionnaire in cohort 1 and 47 pregnant women out of 2,818 eligible participants completing the questionaire in cohort 2. Continuous glucose monitor (CGM) use while pregnant trended upward among cohort 2 (70% vs 37%, P = .02), while reported continuous subcutaneous insulin infusion (CSII) use while pregnant declined (76% vs 64%, P = .04). HbA1c levels trended downward (6.8% cohort 1 vs 6.5% cohort 2, P = .07).

CONCLUSIONS

Self-reported CGM use while pregnant increased over the studied intervals whereas CSII use decreased. Additional evaluation of device use and the potential benefits for T1D pregnancies is needed.

Prevalence of Metabolic Acidosis Among Patients with Chronic Kidney Disease and Hyperkalemia

INTRODUCTION

Although hyperkalemia and metabolic acidosis often co-occur in patients with chronic kidney disease (CKD), the prevalence of metabolic acidosis among patients with CKD and hyperkalemia is understudied. Therefore, we used medical record data from the Research Action for Health Network to estimate this prevalence.

METHODS

Adult patients with CKD stage 3-5, ≥ 1 outpatient potassium value > 5.0 mEq/l, and ≥ 1 outpatient bicarbonate value available were identified. Patients with end stage kidney disease (ESKD) in the prior year were excluded. The prevalence of metabolic acidosis in each calendar year from 2014 to 2017 among patients with CKD and hyperkalemia was estimated using two definitions of hyperkalemia (potassium > 5.0 mEq/l and > 5.5 mEq/l) and metabolic acidosis (bicarbonate < 18 mEq/l and < 22 mEq/l).

RESULTS

In the 2017 patient cohort and among patients with CKD and hyperkalemia, patients with metabolic acidosis were younger (69 versus 74 years), more likely to have advanced CKD (35% versus 13%), and use oral sodium bicarbonate (21% versus 4%) than patients without metabolic acidosis. The prevalence of metabolic acidosis (< 22 mEq/l) ranged from 25 to 29% when hyperkalemia was defined by potassium > 5.0 mEq/l and ranged from 33 to 39% when hyperkalemia was defined by potassium > 5.5 mEq/l.

CONCLUSION

Results demonstrated that prevalence estimates of metabolic acidosis varied based on the definition of hyperkalemia and metabolic acidosis utilized.

Low-carbohydrate dietary pattern on glycemic outcomes trial (ADEPT) among individuals with elevated hemoglobin A1c: study protocol for a randomized controlled trial

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a major cause of morbidity and mortality globally. Strong evidence supports the importance of diet and other lifestyle factors in preventing T2DM. Among individuals with T2DM, low-carbohydrate diets lead to decreases in hemoglobin A1c (HbA1c). However, research on the effects of low-carbohydrate diets on glycemic outcomes among individuals not currently on glucose-lowering medications who have elevated HbA1c is limited.

METHODS

The objective of this randomized controlled trial is to study the effect of a healthy low-carbohydrate diet achieved through behavioral intervention and key food supplementation compared with usual diet on HbA1c and other metabolic risk factors among individuals with HbA1c from 6.0 to 6.9% who are not on glucose-lowering medications. In this parallel trial, 150 participants will be randomized to the intervention or control group for 6 months. The healthy low-carbohydrate diet target is < 40 g of net carbohydrates during the first 3 months and < 40 to 60 net grams for months 3 to 6. This diet is characterized by abundant unsaturated fat and protein, high-fiber foods such as non-starchy vegetables and nuts, and minimal refined carbohydrates. The primary outcome is the difference in HbA1c change from baseline to 6 months in the intervention compared with usual diet group. Secondary outcomes include differences between groups in 6-month changes in fasting glucose, systolic blood pressure, total-to-high-density lipoprotein (HDL) cholesterol ratio, and body weight. Exploratory outcomes include differences in 6-month changes in fasting insulin, homeostasis model assessment of insulin resistance, diastolic blood pressure, waist circumference, and 10-year cardiovascular disease risk. An intention-to-treat analysis will be used.

DISCUSSION

We expect that the results from this study will lead to new approaches for developing and implementing dietary approaches (other than the most commonly used reduced fat diet) that will substantially reduce risk of cardiometabolic disease among adults with or at high risk of T2DM. The study intervention involves behavioral counseling and promotes consumption of dietary components thought to reduce risk of cardiometabolic disease and has expected applicability in clinical practice.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03675360 . Registered on September 18, 2018 (prior to enrolment of the first participant).

Beware Energy Drinks: A Case of a Toxic Triad Syndrome in a Diabetic Patient With Nonalcoholic Fatty Liver Disease

Energy drinks are widely used and very popular. They are touted as "harmless" energy boosters for use in professional, recreational and domestic settings. They are typically high in monosaccharides, and caffeine with other assorted products like ginseng. Careful study of the potential risks of their use is nonexistent while rigorous documentation of their touted energy boosting capacity is also meagre. We present the cautionary case of a 46-year-old Caucasian man with well-controlled type 2 diabetes and nonalcoholic fatty liver disease who developed a toxic triad syndrome of gastritis, hepatitis and pancreatitis within 4 months of commencing daily consumption of 2-3 160z cans of the energy drink Monster Energy. His clinical symptoms and biochemical derangements promptly resolved with stopping the beverage. We discuss the potential risks inherent in unsupervised liberal consumption of energy drinks and the need for both caution and vigilance among clinicians and patients.

Abdominal Distension and Vascular Collapse

We present the case of a 43-year-old gentleman who presented to the emergency room with acute abdominal distension, confusion and vascular collapse. The emergent radiologic imaging obtained showed massive bilateral adrenal enlargement, but despite the initial clinical suspicion of possible overwhelming sepsis and/or massive abdominal/intralesional hemorrhage, lab tests based obtained rapidly confirmed the diagnosis of acute Addisonian crisis which responded dramatically to adrenocorticoid hormone replacement therapy and aggressive fluid resuscitation. The patient's established history of metastatic lung cancer confirmed this as a case of metastatic massive bilateral adrenal metastases with an initial presentation of acute adrenal insufficiency which is uncommon in the setting of metastatic carcinomatosis but more typically associated with lymphomas. Recognition of this clinical possibility is vital to enable rapid diagnosis and consequent life saving therapy.

Sex-associated differences in free fatty acid flux of obese adolescents

CONTEXT

In obesity, increases in free fatty acid (FFA) flux can predict development of insulin resistance. Adult women release more FFA relative to resting energy expenditure (REE) and have greater FFA clearance rates than men. In adolescents, it is unknown whether sex differences in FFA flux occur.

OBJECTIVE

Our objective was to determine the associations of sex, REE, and body composition with FFA kinetics in obese adolescents.

PARTICIPANTS

Participants were from a convenience sample of 112 non-Hispanic white and black adolescents (31% male; age range, 12-18 years; body mass index SD score range, 1.6-3.1) studied before initiating obesity treatment.

MAIN OUTCOME MEASURES

Glucose, insulin, and FFA were measured during insulin-modified frequently sampled iv glucose tolerance tests. Minimal models for glucose and FFA calculated insulin sensitivity index (SI) and FFA kinetics, including maximum (l0 + l2) and insulin-suppressed (l2) lipolysis rates, clearance rate constant (cf), and insulin concentration for 50% lipolysis suppression (ED50). Relationships of FFA measures to sex, REE, fat mass (FM), lean body mass (LBM) and visceral adipose tissue (VAT) were examined.

RESULTS

In models accounting for age, race, pubertal status, height, FM, and LBM, we found sex, pubertal status, age, and REE independently contributed to the prediction of l2 and l0 + l2 (P < .05). Sex and REE independently predicted ED50 (P < .05). Sex, FM/VAT, and LBM were independent predictors of cf. Girls had greater l2, l0 + l2 and ED50 (P < .05, adjusted for REE) and greater cf (P < .05, adjusted for FM or VAT) than boys.

CONCLUSION

Independent of the effects of REE and FM, FFA kinetics differ significantly in obese adolescent girls and boys, suggesting greater FFA flux among girls.

Prevalence and cardiometabolic associations of the glucocorticoid receptor gene polymorphisms N363S and BclI in obese and non-obese black and white Mississippians

OBJECTIVE

Polymorphisms (SNP) in the glucocorticoid receptor (GR) gene can alter sensitivity to glucocorticoids. Previous studies of the N363S and BclI SNP in the GR gene have shown a metabolic syndrome phenotype in mostly non-African populations. The obesity phenotype of African Americans (AA) seems to be more severe than that of Caucasians.

DESIGN

We aimed to assess the prevalence of N363S and BclI in obese and non-obese Caucasian (n=26) and African (n=23) Mississippians (age: 23-63 years) to investigate associations with body composition (body mass index/BMI, waist-to-hip ratio), metabolic parameters (salivary cortisol, fasting glucose and insulin, hemoglobin A1C, fructosamine, HOMA-IR index), and psychological stress perception (blood pressure/BP, perceived stress scale/PSS).

RESULTS

All subjects were homozygous for wildtype N363N. BclI polymorphism genotype frequencies among the 23 AA were: homozygous CC (57%), GG (4%), and heterozygous CG (39%), and among the 26 white women: homozygous CC (35%), GG (19%), and heterozygous CG (46%). Linear and logistic regression analyses including a parsimonious model identified BMI as a statistically significant parameter between the two ethnic groups (BMI was 3.13 kg/m2 higher in AA). Within the AA group, BMI, waist-to-hip ratio, log (HOMA-IR), PSS scores, BP, and hyperlipidemia showed no statistically significant relationships for the BclI polymorphism. PSS scores were 15.2 for AA vs. 14.7 for white women (normal mean: 14.7 vs. 12.8).

CONCLUSION

Black Mississippians have a higher BMI than whites, which may be related to the presence of the BclI polymorphism and increased glucocorticoid sensitivity. Although more blacks (52%) than whites (38%) had elevated BP, PSS scores in both groups suggest that a high BMI is not regarded as abnormal or stressful. This might negatively impact behavior change regarding lifestyle modifications with increased physical activity and healthier food choices. Larger studies, particularly in African populations, are needed to better define metabolic and psychological characteristics in relation to the N363S and BclI GR gene polymorphisms.

Phentermine and topiramate for the management of obesity: a review

Obesity is now a major public health concern worldwide with increasing prevalence and a growing list of comorbidities and complications. The morbidity, mortality and reduced productivity associated with obesity and its complications result in a major burden to health care costs. Obesity is a complex chronic medical syndrome often with multiple different etiologic factors in individual patients. The long term successful management of obesity remains particularly challenging and invariably requires a multifaceted approach including lifestyle and behavioral modification, increased physical activity, and adjunctive pharmacotherapy. Bariatric surgery remains a last resort though at present it has the best results for achieving sustained robust weight loss. Obesity pharmacotherapy has been very limited in its role for long term obesity management because of the past history of several failed agents as well as the fact that presently available agents are few, and generally utilized as monotherapy. The recent FDA approval of the fixed drug combination of phentermine and extended release topiramate (topiramate-ER) (trade name Qsymia™) marks the first FDA approved combination pharmacotherapeutic agent for obesity since the Phen-Fen combination of the 1990s. This review details the history and clinical trial basis for the use of both phentermine and topiramate in obesity therapeutics as well as the results of clinical trials of their combination for obesity treatment in humans. The initial clinical approval trials offer evidence that this fixed drug combination offers synergistic potential for effective, robust and sustained weight loss with mean weight loss of at least 10% of baseline achieved and sustained for up to 2 years in over 50% of subjects treated. It is anticipated that this agent will be the first in a new trend of multi-agent combination therapy for the chronic adjunctive management of obesity.

A case of profound weight loss secondary to use of phentermine

BACKGROUND

Obesity has become particularly prevalent in both the United States and worldwide. Mississippi continues to lead the nation in prevalence of obesity estimates. The proportion of morbidly obese subjects is increasing at a disproportionately greater rate and the burden of obesity and its complications are more prevalent among ethnic minorities. We present the unique case of a Choctaw lady with morbid obesity who has shown a profound response to pharmacotherapy with phentermine.

METHODS

The clinical case history of the patient; a 34-year-old Choctaw lady with morbid obesity, hypertension, hyperlipidemia, and type 2 diabetes is presented, followed by discussion of issues relevant to impacting the obesity epidemic in Mississippi.

RESULTS

A 34-year-old Choctaw lady with 1.5 year follow up was noted to have a peak initial body mass index (BMI) of 62.6 kg/m2 and weight of 176 kg. Since commencement of phentermine, initially at 15 mg daily and slowly up-titrated to 37.5 mg daily, she has lost over 23 kg (13% of baseline peak weight) with a current weight of 153 kg and BMI of 54.4 kg/m2. Accompanying the weight reduction has been sustained normal blood pressure and improvement in glycemic control.

CONCLUSIONS

Phentermine is a viable and important adjunct in the medical approach to weight management in obese subjects. Its potential utility should be considered even among subjects with morbid obesity. Given its cost it could be a cost effective adjunct in comprehensive weight loss programs for Mississippi that may positively impact the ongoing obesity epidemic. There remains a need for more studies of phentermine to better define its place in obesity management.

Does vitamin d deficiency cause hypertension? Current evidence from clinical studies and potential mechanisms

Vitamin D deficiency is widely prevalent across all ages, races, geographical regions, and socioeconomic strata. In addition to its important role in skeletal development and calcium homeostasis, several recent studies suggest its association with diabetes, hypertension, cardiovascular disease, certain types of malignancy, and immunologic dysfunction. Here, we review the current evidence regarding an association between vitamin D deficiency and hypertension in clinical and epidemiological studies. We also look into plausible biological explanations for such an association with the renin-angiotensin-aldosterone system and insulin resistance playing potential roles. Taken together, it appears that more studies in more homogeneous study populations are needed before a firm conclusion can be reached as to whether vitamin D deficiency causes or aggravates hypertension and whether vitamin D supplementation is safe and exerts cardioprotective effects. The potential problems with bias and confounding factors present in previous epidemiological studies may be overcome or minimized by well designed randomized controlled trials in the future.

Spontaneous rib fractures in a black woman with familial hypocalciuric hypercalcemia

BACKGROUND

Familial hypocalciuric hypercalcemia (FHH) is a rare but important consideration in the differential diagnosis of hypercalcemia. FHH results from an autosomal dominantly inherited inactivating mutation of the calcium sensing receptor (CaSR) gene and is typically associated with a benign clinical course and normal bone mineral density.

CASE REPORT

We describe the unusual case of a 57-year old African American woman with spontaneous rib fractures who was found to have FHH due to a novel set of polymorphisms of the CaSR gene. She also had hypertension, esophageal reflux disease treated with proton pump inhibitors, osteopenia by DEXA scanning, and a prior left ankle fracture in the absence of significant trauma. There was no suggestive family history and her only sibling had a normal serum calcium. The patient was evaluated extensively for potential causes of osteoporotic fractures.

CONCLUSIONS

It is imperative to screen for FHH using 24-hour urinary calcium and creatinine excretion in subjects with hypercalcemia irrespective of ethnicity and a history of non-traumatic rib fractures. This approach may prevent unnecessary neck exploration for parathyroidectomy which is unwarranted in FHH.

Differential effects of oral hypoglycemic agents on glucose control and cardiovascular risk

Cardiovascular disease (CVD) burden remains the predominant cause of mortality and morbidity in the United States and in most of the developed world. The ongoing twin epidemics of obesity and type 2 diabetes mellitus provide a groundswell source for sustaining this trend for the foreseeable future (increasing the prevalence of CVD by 2-4 times), unless radical changes are made in public health policy. Oral hypoglycemic agents (OHAs) remain a mainstay for management of type 2 diabetes in most practice settings. Although these agents are primarily prescribed to achieve better glycemic control, it is important to evaluate what effects they have on cardiovascular risk and whether there are significant differences in effects among the different OHAs. This review presents the available data on the effects of the various OHAs on cardiovascular risk surrogates and actual events in retrospective and prospective study design settings.

Acanthosis Nigricans in Patients with Nonalcoholic Steatohepatitis: An Uncommon Finding

OBJECTIVE

To determine the prevalence and the metabolic characteristics of acanthosis nigricans (AN) in a group of 28 study subjects with biopsy-proven nonalcoholic steatohepatitis (NASH).

METHODS

The study participants (15 female and 13 male patients, 20 of whom were white subjects; mean body mass index, 32.7 +/- 5.7 kg/m2; mean age, 45.7 +/- 11.3 years) underwent an oral glucose tolerance test (OGTT), frequently sampled intravenous glucose tolerance test (FSIGT), and fasting metabolic panels. AN status was clinically determined, and fat mass was measured by dual-energy x-ray absorptiometry.

RESULTS

All study subjects had insulin resistance (IR), and 15 (54%) had the metabolic syndrome (by Adult Treatment Panel III criteria). Of the 28 patients, 4 (14%) had AN (AN+) and 24 did not (AN-). AN+ subjects had a higher body mass index (37.7 +/- 5.6 versus 31.5 +/- 4.3 kg/m2), fat mass (38.9 +/- 4.0 versus 29.2 +/- 2.3 kg), and leptin levels (17.2 +/- 3.9 versus 9.3 +/- 1.6 ng/mL) (P<0.05). They also had significantly higher indices of insulin secretion: fasting and stimulated insulin and C-peptide levels from OGTT and FSIGT. Metabolic syndrome prevalence was 40% in AN- versus 75% in AN+ subjects (not significantly different). Although the AN+ group had significantly lower fasting and OGTT-derived indices of insulin sensitivity in comparison with the AN- group, their FSIGT indices were similar. Waist circumference (a surrogate of visceral adiposity) and cytokine profiles were similar in the AN+ and AN- groups.

CONCLUSION

AN was not highly prevalent in our study cohort with NASH, despite the high prevalence of IR. Hyperinsulinemia and total adiposity, rather than visceral adiposity and IR, were the indices most predictive of AN. The use of AN as an index of IR in patients with NASH appears to have limited diagnostic value.

Venous Thrombosis and Conjugated Equine Estrogen in Women Without a Uterus

BACKGROUND

Postmenopausal hormone therapy has been associated with a 2- to 3-fold increased risk of venous thromboembolism (VT) (including deep vein thrombosis and pulmonary embolism) in observational studies and secondary prevention clinical trials. Clinical trial data on the effects of estrogen alone on VT are limited.

METHODS

The Women's Health Initiative estrogen trial enrolled 10 739 women aged 50 to 79 years without a uterus. Participants were randomly assigned to receive conjugated equine estrogen (0.625 mg/d) or placebo.

RESULTS

During a mean of 7.1 years, VT occurred in 111 women randomly assigned to receive estrogen (3.0 per 1000 person-years) and 86 randomly assigned to receive placebo (2.2 per 1000 person-years; hazard ratio, 1.32; 95% confidence interval, 0.99-1.75). Deep venous thrombosis was reported in 85 women randomly assigned to receive estrogen (2.3 per 1000 person-years) and 59 randomly assigned to receive placebo (1.5 per 1000 person-years; hazard ratio, 1.47; 95% confidence interval, 1.06-2.06). The VT risk was highest in the first 2 years. There were no significant interactions between estrogen use and age, body mass index, or most other VT risk factors. Comparison of Women's Health Initiative VT findings for estrogen and previous Women's Health Initiative findings for estrogen plus progestin showed that the hazard ratios for estrogen plus progestin were significantly higher than those for estrogen alone (P = .03), even after adjusting for VT risk factors.

CONCLUSION

An early increased VT risk is associated with use of estrogen, especially within the first 2 years, but this risk increase is less than that for estrogen plus progestin.

Novel pharmacologic agents for type 2 diabetes

After many decades of relative therapeutic stagnation since the initial discovery of insulin, followed by some modifications on its structure and only having sulfonylureas and biguanides for many years, the last decade has seen a surge in new therapeutic options for the management of diabetes. The results of the United Kingdom Prospective Diabetes Study and Kumamoto study indicate the need for aggressive glycemic control and the slow inexorable clinical deterioration associated with type 2 diabetes overtime. The propensity for weight gain and hypoglycemia are the two major limitations that subcutaneous insulin and sulfonylureas have been particularly prone to. The newer antidiabetic medications and those on the horizon attempt to address these limitations. GLP-1 agonists and the DPP-IV inhibitors exploit the innate incretin system to improve glycemia while promoting satiety and weight management. Like GLP-1 related compounds, pramlintide offers the potential to address postprandial hyperglucagonemia associated with type 2 diabetes only limited by the multiple injections and gastrointestinal side effects. The glitazars offer the hope ofa new approach to diabetes care addressing not just glycemia, but dyslipidemia and other components of the metabolic syndrome, though the side effect profile remains a major unknown. The INGAP peptide represents the holy grail of diabetes care as it offers the potential of a new paradigm: that of islet regeneration and potential for a cure. But at this stage, with no human data available, it remains highly speculative. Beyond these and other novel agents being developed to meet the challenge of the worldwide epidemic of diabetes, the central place of insulin in diabetes care cannot be forgotten. In view of this the continued efforts of improvement in insulin delivery, kinetics and action have spurred such innovations as the various inhaled insulins and new insulin analogues. There is cause for guarded optimism and excitement about the years ahead. There is reason to expect that despite the growing burden of diabetes worldwide, we will be better equipped to manage it and its comorbidities and prevent its onset and possibly even cure it.

The relationship between obesity and serum 1,25-dihydroxy vitamin D concentrations in healthy adults

Several previous reports of small cohorts have found significantly higher serum 1,25-dihydroxy vitamin D (1,25-vit D) in obese compared with nonobese whites. Based on these reports and on recent in vitro studies of adipocytes which suggest that administration of 1,25-vit D can stimulate lipogenesis and inhibit lipolysis, some investigators have proposed that high 1,25-vit D may play a role in promoting or maintaining adipocyte triglyceride stores in obese adults. To test the hypothesis that obesity is commonly associated with increased 1,25-vit D, we examined the relationships between calciotropic hormones and body adiposity in a large cohort of healthy adults. Serum intact PTH, 25-hydroxy vitamin D, and 1,25-vit D were measured in the postabsorptive state in 302 healthy adults who were Caucasian (n = 190; 71% female), African-American (n = 84; 89% female), and of other race/ethnicity (n = 28; 61% female). Results from the 154 obese subjects [body mass index (BMI) 37.3 +/- 5.8 kg/m(2); range, 30.1-58.2 kg/m(2)] were compared with those from 148 nonobese (BMI 25.6 +/- 2.9 kg/m(2); range, 18.0-29.9 kg/m(2)) age-, race-, and sex-matched participants. Body composition was measured by dual energy x-ray absorptiometry. Serum intact PTH was positively correlated with both BMI (r = 0.42; P < 0.0001) and body fat mass (r = 0.37; P < 0.0001). Serum 25-hydroxy vitamin D was negatively correlated with BMI (r = -0.4; P < 0.0001) and body fat mass (r = -0.41; P < 0.0001). Serum 1,25-vit D was also negatively correlated with BMI (r = -0.26; P < 0.0001) and body fat mass (r = -0.25; P = 0.0001). Serum 1,25-vit D was significantly lower in obese than nonobese subjects (105.7 +/- 41.1 vs. 124.8 +/- 36.7 pmol/liter; P < 0.0001) in both Caucasian and African-American adults. We conclude that, because 1,25-vit D concentrations fall with increasing adiposity, it appears unlikely that elevation in 1,25-vit D is an important hormonal mechanism causing or maintaining obesity in adults.

Efficacy of orlistat as an adjunct to behavioral treatment in overweight African American and Caucasian adolescents with obesity-related co-morbid conditions

This pilot study compared the efficacy of orlistat as an adjunctive treatment for obesity between African American and Caucasian adolescents. Twenty obese adolescents with obesity-related co-morbid conditions underwent measurements of body composition, glucose homeostasis by frequently sampled intravenous glucose tolerance test (FSIGT), and fasting lipids before and after 6 months treatment with orlistat 120 mg tid in conjunction with a comprehensive behavioral program. Weight (p < 0.05), BMI (p < 0.001), total cholesterol (p < 0.001), LDL cholesterol (p < 0.001), fasting insulin (p < 0.02) and fasting glucose (p < 0.003) were lower after treatment. Insulin sensitivity, measured during the FSIGT, improved significantly (p < 0.02), as did fasting indices such as the homeostasis model assessment for insulin resistance (p < 0.01). African American subjects exhibited significantly less improvement in weight (p < 0.05), BMI (p < 0.01), waist circumference (p = 0.03), and insulin sensitivity (p = 0.05). Improvements in cholesterol were not significantly different between African Americans and Caucasians. We conclude that Caucasians lost more weight and had greater improvements in insulin sensitivity than African Americans, but both exhibited improvements in plasma lipids. The true benefit of orlistat treatment over a comprehensive behavioral program remains to be determined in placebo-controlled trials.

A pilot study of pioglitazone treatment for nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) is a common chronic liver disease for which there is no known effective therapy. A proportion of patients with NASH progress to advanced fibrosis and cirrhosis. NASH is considered one of the clinical features of the metabolic syndrome in which insulin resistance plays a central role. This prospective study evaluates the role of insulin-sensitizing agent in treatment of NASH. Eighteen nondiabetic patients with biopsy-proven NASH were treated with pioglitazone (30 mg daily) for 48 weeks. Tests of insulin sensitivity and body composition as well as liver biopsies were performed before and at the end of treatment. By 48 weeks, serum alanine aminotransferase values fell to normal in 72% of patients. Hepatic fat content and size as determined by magnetic resonance imaging decreased, and glucose and free fatty acid sensitivity to insulin were uniformly improved. Histological features of steatosis, cellular injury, parenchymal inflammation, Mallory bodies, and fibrosis were significantly improved from baseline (all P < 0.05). Using strict criteria, histological improvement occurred in two-thirds of patients. Pioglitazone was well tolerated; the main side effects were weight gain (averaging 4%) and an increase in total body adiposity. In conclusion, these results indicate that treatment with an insulin-sensitizing agent can lead to improvement in biochemical and histological features of NASH and support the role of insulin resistance in the pathogenesis of this disease. The long-term safety and benefits of pioglitazone require further study.

The roles of insulin resistance, hyperinsulinemia, and thiazolidinediones in cardiovascular disease

Although it is difficult to distinguish between the relative effects of insulin resistance and hyperinsulinemia, insulin resistance is clearly associated with significantly increased cardiovascular and cerebrovascular risk. This effect is consistent across the spectrum of worsening glycemic control, from the onset of impaired glucose tolerance to the development of clinical diabetes. It is more difficult to discriminate between the roles of elevated circulating insulin and proinsulin levels; the association between insulin levels and cardiovascular risk is weak. The thiazolidinediones (TZDs) significantly improve insulin sensitivity and exert numerous effects on the vascular bed, including improved endothelial function, decreased vascular inflammation, decreased plasma free fatty acid levels, improved dyslipidemic profiles, and inhibition of vascular smooth muscle proliferation. These findings provide increasing evidence to suggest that the TZDs may have a beneficial effect on atherosclerosis and may reduce the incidence and severity of adverse cardiovascular outcomes. These effects remain to be substantiated by the results of large outcomes studies to evaluate the impact of glycemic control and reversal of insulin resistance on cardiovascular events.

Is there a therapeutic role for octreotide in patients with ectopic Cushing's syndrome?

Cushing's syndrome (CS) due to ectopic ACTH secretion (EAS) has a high morbidity and mortality, because of the underlying tumor and the sequelae of severe hypercortisolemia. Therefore, rapid treatment of ectopic CS is mandatory. Scintigraphy shows that up to 80% of ectopic ACTH-producing tumors have somatostatin receptors. While this suggests that somatostatin analogs may reduce ACTH production and treat patients with EAS, the therapeutic role of these agents is still evolving. Here we demonstrate the spectrum of responses to octreotide therapy in 3 patients with EAS. Diagnostic imaging with the 111In-pentetreotide scan did not predict the therapeutic response to octreotide. Two patients with positive somatostatin receptor scintigraphy failed to respond to octreotide, while one with a negative scan reached eucortisolemia on a maintenance dose of 75 microg octreotide twice daily or octreotide LAR 30 mg per month. We conclude that octreotide is not a first line agent to control hypercortisolemia but may be a useful agent when other inhibitors of steroidogenesis fail or parenteral administration is required. Before therapy an octreotide challenge test may predict therapeutic response. Cortisol levels should be monitored regularly on somatostatin analog therapy, because of its unpredictable long-term pharmacodynamic profile.

Improvement in hypertrophic cardiomyopathy after significant weight loss: case report

A 17-year-old obese boy found to have familial apical hypertrophic cardiomyopathy on routine screening was enrolled in a weight loss program on the basis of the hypothesis that significant weight loss would improve his cardiac status. He was followed with serial dual-energy x-ray absorptiometry, electrocardiography, echocardiography, and blood pressure and pulse rate measurements. Within 1 year, he lost 49 kg, with a body mass index reduction from 43.6 to 28.1 kg/m2 and associated reductions in systolic blood pressure, diastolic blood pressure, pulse pressure, mean heart rate, rate pressure product, and echocardiographic indices of left ventricular mass that resulted in a change from the initial geometric finding of eccentric left ventricular hypertrophy to a "normal" left ventricular mass with minimal asymmetric apical left ventricular thickening. Significant weight loss in an obese adolescent with presumed familial apical hypertrophic cardiomyopathy was associated with striking improvement in cardiac functional indices, which could have profound implications for long-term cardiovascular risk.

Indices of insulin action, disposal, and secretion derived from fasting samples and clamps in normal glucose-tolerant black and white children

OBJECTIVE

To validate fasting indices of insulin sensitivity and secretion in a diverse pediatric population against gold standard estimates from euglycemic and hyperglycemic clamps.

RESEARCH DESIGN AND METHODS

A total of 31 children (mean BMI 25.1 +/- 4.9 kg/m(2), mean age 8.7 +/- 1.4 years, 15 girls and 16 boys, 12 black and 19 white) underwent euglycemic and hyperglycemic clamps 2-6 weeks apart to derive insulin sensitivity indices (SI (Eug clamp) and SI (Hyper clamp)). Fasting samples were used to derive the homeostasis model assessment of insulin resistance index (HOMA-IR), HOMA of percent beta-cell function (HOMA-B%), quantitative insulin sensitivity check index (QUICKI), insulinogenic index, antilipolytic insulin sensitivity index (ISI-FFA), and C-peptide-to-insulin ratio.

RESULTS

The QUICKI correlated best with SI (Eug clamp) (r = 0.69, P < 0.05) and had greater correlations to SI (Eug clamp) than did either SI (Hyper clamp) (r = 0.45, P < 0.05) or the HOMA-IR (r = -0.51, P < 0.05). Both fasting insulin and the insulinogenic index correlated well with first- and steady-phase insulin secretion (r's from 0.79 to 0.86, P < 0.05). HOMA-B% was not as highly correlated (r = 0.69-0.72, P < 0.05). Fasting C-peptide-to-insulin ratio was not significantly correlated with clamp-derived metabolic clearance rate of insulin. ISI-FFA was not correlated with the degree of free fatty acid suppression obtained from the clamps.

CONCLUSIONS

The QUICKI, fasting insulin, and the insulinogenic index all closely correlate with corresponding clamp-derived indices of insulin sensitivity and secretion in this diverse pediatric cohort. These results, if replicated in similarly diverse populations, suggest that estimates based on fasting samples can be used to rank order insulin secretion and sensitivity in pediatric cohorts.

Three-month tolerability of orlistat in adolescents with obesity-related comorbid conditions

OBJECTIVE

To study the safety, tolerability, and potential efficacy of orlistat in adolescents with obesity and its comorbid conditions.

RESEARCH METHODS AND PROCEDURES

We studied 20 adolescents (age, 14.6 +/- 2.0 years; body mass index, 44.1 +/- 12.6 kg/m(2)). Subjects were evaluated before and after taking orlistat (120 mg three times daily) and a multivitamin for 3 months. Subjects were simultaneously enrolled in a 12-week program emphasizing diet, exercise, and strategies for behavior change.

RESULTS

Participants who completed treatment (85%) reported taking 80% of prescribed medication. Adverse effects were generally mild, limited to gastrointestinal effects observed in adults, and decreased with time. Three subjects required additional vitamin D supplementation despite the prescription of a daily multivitamin containing vitamin D. Weight decreased significantly (-4.4 +/- 4.6 kg, p < 0.001; -3.8 +/- 4.1% of initial weight), as did body mass index (-1.9 +/- 2.5 kg/m(2); p < 0.0002). Total cholesterol (-21.3 +/- 24.7 mg/dL; p < 0.001), low-density lipoprotein-cholesterol (-17.3 +/- 15.8 mg/dL; p < 0.0001), fasting insulin (-13.7 +/- 19.0 microU/mL; p < 0.02), and fasting glucose (-15.4 +/- 7.4 mg/dL; p < 0.003) were also significantly lower after orlistat. Insulin sensitivity, assessed by a frequently sampled intravenous glucose-tolerance test, improved significantly (p < 0.02).

DISCUSSION

We conclude that, in adolescents, short-term treatment with orlistat, in the context of a behavioral program, is well-tolerated and has a side-effect profile similar to that observed in adults, but its true benefit versus conventional therapy remains to be determined in placebo-controlled trials.

Effects of orlistat on fat-soluble vitamins in obese adolescents

STUDY OBJECTIVES

To determine whether orlistat causes fat-soluble vitamin deficiencies in African-American and Caucasian adolescents.

DESIGN

Prospective, open-label pilot study.

SETTING

Warren Grant Magnuson Clinical Center of the National Institutes of Health.

PATIENTS

Seventeen adolescents with body mass indexes above the 95th percentile for age, race, and gender who also had at least one obesity-related comorbid condition.

INTERVENTION

Subjects received orlistat 120 mg 3 times/day and a daily multivitamin supplement containing vitamin A 5000 IU, vitamin D 400 IU, vitamin E 300 IU, and vitamin K 25 microg.

MEASUREMENTS AND MAIN RESULTS

During 3-6 months of orlistat treatment, acute absorption of retinol (vitamin A) was not significantly altered, but absorption of alpha-tocopherol (vitamin E) was significantly reduced compared with baseline levels (p<0.001). Serum levels of vitamins A and E did not change significantly; however, there was a nonsignificant decrease in vitamin K. Mean vitamin D levels were significantly reduced compared with baseline (p<0.02) after 1 month of orlistat, despite multivitamin supplementation.

CONCLUSION

It may be prudent to monitor vitamin D concentrations in adolescents who take orlistat, even when a multivitamin is prescribed.

Differences in insulin secretion and sensitivity of Caucasian and African American prepubertal children

OBJECTIVE

To investigate whether differences in body composition of African American children (AA) and Caucasian children (C) explain differences in insulin sensitivity and secretion.

STUDY DESIGN

Prepubertal nondiabetic children (31 AA and 54 C) were studied; 84% were overweight. Participants underwent a 2-hour hyperglycemic clamp, to estimate insulin sensitivity (SI(clamp)) and secretion, and dual energy x-ray absorptiometry, to assess body composition.

RESULTS

AA had greater total body fat mass (P =.01), fasting, 1st phase, 2nd phase, and steady state insulin levels (P <.05). AA and C had similar glucose disposal rates, but AA had lower SI(clamp) (P <.05). Fasting, 1st phase, and steady state C-peptide were less in C (P <.05), whereas corresponding C-peptide/insulin ratios were higher (all P <.005). Insulin levels and SI(clamp) remained different in AA and C after adjustment for body fat or lean mass differences. Analyses restricted to only overweight AA and C showed similar trends.

CONCLUSION

Prepubertal African American children have higher baseline and glucose-stimulated insulin and C-peptide levels, as well as reduced insulin sensitivity that is not entirely explained by differences in adiposity. The lower C-peptide/insulin molar ratio in AA suggests that they probably have lower hepatic insulin clearance than Caucasian children.

Comparison of insulin sensitivity, clearance, and secretion estimates using euglycemic and hyperglycemic clamps in children

The euglycemic clamp is the gold standard for estimating insulin sensitivity. The hyperglycemic clamp is easier to perform and is the gold standard for estimating beta-cell secretion. Reports in adults suggest that hyperglycemic clamps can estimate insulin sensitivity with results equivalent to euglycemic clamps. We investigated whether insulin sensitivity measures from both clamps are equivalent in children. Thirty-one lean and obese children (mean body mass index, 25.1 +/- 4.9 kg/m(2); mean age, 8.7 +/- 1.4 yr; 15 girls and 16 boys; 12 black and 19 white) were studied. All subjects underwent hyperglycemic clamps, then euglycemic clamps 2-6 wk later. Body composition was estimated by dual energy x-ray absorptiometry. Visceral and sc abdominal fat was estimated by abdominal magnetic resonance imaging. Whole-body glucose disposal and insulin sensitivity (SI clamp) derived from both clamps and normalized for total or visceral fat and lean mass were significantly correlated (r, 0.45-0.65; P < 0.05). However, absolute SI clamp values were not equivalent. Bland-Altman comparisons found that SI clamp estimates from hyperglycemic clamps became less precise as SI clamp increased. There were significant correlations between indices of beta-cell secretion from the hyperglycemic clamp and mean C-peptide values from the euglycemic clamp (P < 0.05). However, no correlation was found between measures of total insulin clearance (derived from the euglycemic clamp) and surrogates of hepatic insulin clearance (derived from the hyperglycemic clamp). In this cohort of diverse children, SI clamp values from euglycemic and hyperglycemic clamps were significantly correlated but were not equivalent, whereas the insulin clearance measures were not correlated. It cannot be assumed that the hyperglycemic clamp obviates the need for euglycemic clamp studies to accurately estimate insulin sensitivity in children.

Relationships between walk/run performance and cardiorespiratory fitness in adolescents who are overweight

BACKGROUND AND PURPOSE

Little is known about the methods used to assess the physical fitness of adolescents who are overweight. We investigated the relationship between walk/run performance and cardiorespiratory fitness in adolescents who are overweight.

SUBJECTS

Eight African-American adolescents (5 female, 3 male) and 10 Caucasian adolescents (5 female, 5 male) who were overweight (mean age=14.5 years, SD=2.0, range=12-17; mean body mass index [BMI]=42.9 kg/m2, SD=11.5) participated in this study.

METHODS

Subjects performed a 12-minute walk/run test. The distances traveled at both 9 minutes (D9) and 12 minutes (D12) were recorded, and the distance traveled between 9 and 12 minutes (D9-12) was calculated. Subjects also completed a maximal cycle ergometry test, during which peak oxygen uptake (VO2peak), anaerobic threshold (AT), peak power (Wpeak), and power at the anaerobic threshold (WAT) were determined. Body composition was determined by air displacement plethysmography.

RESULTS

The mean percentage of body fat was 48.6% (SD=5.3%, range=40.3%-60.4%). Percentage of body fat and BMI were each inversely related to D9, D12, and VO2peak (all P<.005). Peak oxygen uptake (r=.72, P=.0001), VO2peak/kg lean body mass (r=.60, P<.005), Wpeak (r=.88, P<.0001), and WAT (r=.72, P=.0007) were all related to D12, with greater r values than for D9. If D9-12was included in regression analyses, D9 did not account for additional variance in any of the cycle ergometry variables.

DISCUSSION AND CONCLUSION

These results suggest that an easily obtained measurement of physical performance (distance traveled during a 12-minute walk/run test) is related to cardiorespiratory fitness and to body composition in adolescents who are overweight. The 12-minute walk/run distance is more predictive of cycle ergometry test results than the 9-minute distance.

The relation between skeletal maturation and adiposity in African American and Caucasian children

OBJECTIVE

African American children have earlier pubertal and skeletal maturation and a higher body mass index (BMI) than Caucasian children. We tested the hypothesis that advanced bone age in African American children is accounted for by their greater adiposity.

STUDY DESIGN

We studied 252 African American (n = 97) and Caucasian (n = 155) children aged 5 to 12 years. Skeletal age was determined by a radiologist blinded to clinical details. The difference between bone age (BA) and chronological age (CA) (noted as BA - CA) and the ratio of bone age to chronological age (BA/CA) were determined. Analysis of covariance was used to adjust skeletal maturation for the effects of adiposity, as measured by BMI, BMI standard deviation score (BMI SDS), and fat mass by dual energy x-ray absorptiometry (DXA).

RESULTS

African American children were significantly heavier than Caucasians (BMI SDS 2.7 +/- 3.4 vs 1.7 +/- 2.4, P <.05). Both BA - CA (0.75 +/- 1.46 vs 0.28 +/- 1.38, P <.05) and BA/CA (1.09 +/- 0.17 vs 1.03 +/- 0.16, P <.05) were significantly greater in African Americans than Caucasians. BA - CA and BA/CA were significantly correlated with lean body mass, BMI, BMI SDS, and DXA fat mass (all r > 0.46, P <.001). Neither BA - CA nor BA/CA of African Americans and Caucasians were significantly different after correction for lean body mass and measures of adiposity, including BMI, BMI SDS, or DXA fat mass.

CONCLUSION

Skeletal age is more advanced in African American than Caucasian children and is significantly related to body mass. In large measure, the advancement in skeletal maturation of prepubertal and early pubertal African American children can be accounted for by their greater adiposity.

A case of spurious hypercalcitoninemia: a cautionary tale on the use of plasma calcitonin assays in the screening of patients with thyroid nodules for neoplasia

The measurement of plasma CT has an important role as a screening test for medullary thyroid carcinoma (MTC) in patients with thyroid nodules. However, elevated plasma CT levels should be interpreted within the context of the overall clinical picture in each individual case and carefully validated before therapeutic decisions are made. We present the case of a 17-yr-old girl who was referred to us with a thyroid nodule and elevated plasma CT levels, as measured by a one-site RIA not involving prior plasma extraction. Plasma CT was re-measured using two different methods, a RIA with prior plasma extraction and a two-site immunochemiluminometric assay (ICMA), and was either very low or undetectable. Subsequently, samples were re-assayed using the initially applied CT RIA; plasma CT levels were again found to be elevated. These elevations were of a spurious nature, probably caused by the presence of an unidentified substance in the patient's plasma interfering with the measurement of CT in the initially used RIA. Our patient was eventually diagnosed with Hashimoto's thyroiditis, and had no evidence of MTC. As several conditions can cause either true or spurious hypercalcitoninemia, we suggest that elevated plasma CT levels should be confirmed at least once before other extensive diagnostic investigations are initiated or thyroidectomy is recommended. Finally, the assay selected should detect only the mature CT molecule.

Relation of acanthosis nigricans to hyperinsulinemia and insulin sensitivity in overweight African American and white children

OBJECTIVES

Acanthosis nigricans (AN) has been proposed as a reliable marker of hyperinsulinemia, but its utility for predicting hyperinsulinism has not been systematically evaluated in overweight children. We examined the relationship of AN to hyperinsulinemia and body adiposity.

STUDY DESIGN

One hundred thirty-nine children underwent physical examination for AN, body composition studies, an oral glucose tolerance test, and a hyperglycemic clamp.

RESULTS

Thirty-five children (25%) had AN. AN was more prevalent in African Americans (50.1%) than in white subjects (8.2%, P < .001). Independent of race, children with AN had greater body weight and body fat mass (P < .001); greater basal and glucose-stimulated insulin levels during oral glucose tolerance test (P < .001); greater first-phase, second-phase, and steady-state insulin levels (P < .001); and lower insulin sensitivity (P < .001) during the hyperglycemic clamp. After adjusting for body fat mass and age, none of these differences remained significant. When categorized by fasting insulin, 35% with fasting insulin levels > 20 microU/mL and 50% with fasting insulin levels > 15 microU/mL did not have AN. Eighty-eight percent of children with fasting insulin levels > or = 15 microU/mL had a body mass index SD score > or = 3.0.

CONCLUSIONS

AN is not a reliable marker for hyperinsulinemia in overweight children. Children with a race-, sex-, and age-specific body mass index SD scores > or = 3.0 should be screened for hyperinsulinemia, whether or not they have AN.