Division of Endocrinology, Metabolism and Nutrition

The fellowship has strong educational, research and patient care components and is supported by the division’s full time and volunteer faculty. Training is based at Robert Wood Johnson University Hospital, New Brunswick, New Jersey, the primary teaching hospital of Robert Wood Johnson Medical School.

In order to achieve the goals of the program, the twenty-four months of training are structured into two progressively advancing levels of ACGME competency-based objectives, with an aim of building the medical knowledge, technical skills and competencies of the trainee.

Fellows in the Endocrinology, Diabetes and Metabolism training program will acquire expertise to care for patients with a vast diversity of endocrine and metabolic problems. Our emphasis is to provide fellows with solid medical knowledge and technical skills that will make you a clinically astute endocrinologist. This will prepare fellows for productive careers as general endocrinologists or subspecialists. Clinical training with academic faculty motivated for inquiry and scholarship will also prepare the fellow for academic endocrinology as a clinician or physician scientist. We feel that the more career options fellows have once they leave the program the better.

Through caring for our diverse patient population, fellows learn to treat a wide array of disease states including diabetes mellitus, obesity, thyroid conditions, bone and mineral metabolism disorders, adrenal and pituitary disorders.

The curriculum addresses the art, science and business of medicine. Weekly conferences include journal clubs, research presentations, a core didactic curriculum conference, case management conferences, and tumor boards.

Fellows are involved in the educational training of residents and medical students during their electives in our division and as preceptors in the physical diagnosis course.

Fellows participate in quality improvement/performance improvement projects and contribute to committees including but not limited to the graduate medical education committee, hospital diabetes committee, and hospital nutrition committee.

In addition, fellows have the opportunity to take part in both laboratory-based basic scientific research and clinical research projects in the division of Endocrinology, Department of Medicine, and Rutgers Biomedical and Health Sciences. Our fellows are funded to present their research at national conferences yearly.

We encourage the fellows to seek educational and professional experiences outside of our institution by joining regional and national professional societies and attending outside educational opportunities. We purchase a subscription to the Endocrine Society’s “Fellows Training Series” for each fellow which includes an in-training exam, online procedural training modules, and subspecialty modules. Fellows are supported to attend a board review course in their second year of training. Our faculty is well connected to several major national societies such as the ADA, ATA, Pituitary Society, Endocrine Society and AACE and we encourage fellows to begin long-term involvement in these premier societies.

The combination of the clinical activity, conferences and research opportunities creates a well-balanced program in which to develop in the field of endocrinology and launch successful careers.

Training takes place at the Rutgers Health faculty practice (outpatient) and Robert Wood Johnson University Hospital (inpatient). The training program provides opportunities to observe and manage a diverse population of inpatients, outpatients and consults along the spectrum of endocrine disease. Fellows are supervised and closely mentored by dedicated faculty.

Fellows rotate on inpatient consultation service, ambulatory clinic, and subspecialty/research blocks.

In the Rutgers Health faculty practice the fellows rotate through general endocrine and subspecialty clinics including osteoporosis, pediatrics, women's health, transgender and thyroid procedure clinics. Each fellow maintains a continuity clinic which provides them with the opportunity to learn the course of disease and develop long-term patient relationships. Our clinic has professional CGM, a DXA machine, an ultrasound machine, and a CDE always accessible to the fellows.

Our trainees are an integral part of the Robert Wood Johnson University Hospital multidisciplinary teams that care for patients undergoing cardiovascular surgery, heart transplants, kidney and pancreas transplants, stem cell transplants, bariatric surgery and pituitary surgeries.

As part of the Cancer Institute of New Jersey we often collaborate on patients with neuroendocrine tumors and immune related endocrinopathies.

We have the capabilities to treat our patients with radioactive iodine for hyperthyroidism and thyroid cancer, gamma knife radiosurgery, gender affirmation surgery and perform petrosal sinus sampling, adrenal vein sampling and parathyroid venous sampling.

Fellows may participate in research projects related to clinical, basic science or both with any of the fulltime faculty members in the division. Clinical trials sponsored by the National Institutes of Health and the pharmaceutical industry are routinely conducted in the division. Current faculty research interests include osteoporosis and other metabolic bone diseases, pituitary disease, hyperlipidemia, diabetes and obesity, exercise physiology, and thyroid disorders.

Recent Publications:

• Ten S, Bhangoo A, Buettner C. Tirzepatide for Congenital Generalized Lipodystrophy. N Engl J Med. 2025 Jan 29. doi: 10.1056/NEJMc2413871.
• Izarraras K, Shah A, Prasad K, Tan H, Zhou Z, and Bhattacharya M. Kisspeptin Mitigates Hepatic De Novo Lipogenesis in Metabolic-Dysfunction-Associated Steatotic Liver Disease, Cells; 2025; 14:1289.
• Meng L, Shapses SA, Wang X. Parathyroidectomy Reduces Inflammatory Cytokines and Increases Vitamin D Metabolites in Patients With Primary Hyperparathyroidism. Endocr Pract. 2025 Jan;31(1):52-58. doi: 10.1016/j.eprac.2024.10.005.
• Shah A, Xu H, Kwon H, Wondisford FE. In Vivo Glycerol Metabolism in Glycerol Kinase Deficiency Disease, Journal of Inherited Metabolic Disease Reports; 2024; 65: 392-400.
• L Meng, X Wang, JL Carson, Y Schlussel, SA Shapses. Vitamin D Binding Protein and Postsurgical Outcomes and Tissue Injury Markers After Hip Fracture: A Prospective Study. The Journal of Clinical Endocrinology & Metabolism 2024; 109 (1), e18-e24.
• Sakamoto K, Butera M, Zhou C, Maurizi G, Chen B, Shawkat A, Patlolla L, Thakker K, Calle V, Morgan D, Rahmouni K, Schwartz G, Tahiri A, Buettner C. Overnutrition causes insulin resistance and metabolic disorder through increased sympathetic nervous system activity. Cell Metab. 2024 Oct 15:S1550-4131(24)00376: PMID: 39437790.
• Buettner C, Sakamoto K, Butera A. M. Why do some individuals with obesity remain metabolically healthy? Trends Endocrinol Metab.; 2024 Jul 2:S1043-2760(24)00176-0 PMID: 38960837.
• Cohn AY, Grant LK, Nathan MD, Wiley A, Abramson M, Harder JA, Crawford S, Klerman EB, Scheer FAJL, Kaiser UB, Rahman SA, Joffe H. Effects of Sleep Fragmentation and Estradiol Decline on Cortisol in a Human Experimental Model of Menopause. J Clin Endocrinol Metab. 2023 Oct 18;108(11):e1347-e1357. doi: 10.1210/clinem/dgad285. PMID: 37207451; PMCID: PMC10584010.
• Bisno DI, Lubitz S, Marshall I, Cohen DA. A National Survey of United States-Based Endocrinologists Who Prescribe Gender-Affirming Hormone Therapy. Endocr Pract. 2023 Jun;29(6):465-470. doi: 10.1016/j.eprac.2023.03.003. Epub 2023 Mar 9. PMID: 36906069.
• Correa R, Miragaya J, Cohen DA, Hoang TD, Jasim S, Lieb DC, Weber SL, Bird MD, Stec C; Clinical Practice Guidelines Oversight Committee. Protocol for Development of American Association of Clinical Endocrinology Clinical Practice Guidelines and Consensus Statements: Summary of Methodology, Process, and Policy - 2023 Update. Endocr Pract. 2023 May;29(5):341-348. doi: 10.1016/j.eprac.2023.01.012. PMID: 37150580.
• Bassin SR, Lubitz S. Integrating Basic Science into Endocrine Clinical Electives. Med Sci Educ. 2023 Jun 30;33(4):835-839. doi: 10.1007/s40670-023-01824-w. PMID: 37546212.
• Zhou C, Ruiz HH, Ling L, Maurizi G, Sakamoto K, Liberini CG, Wang L, Stanley A, Egritag HE, Sanz SM, Lindtner C, Butera MA, Buettner C. Sympathetic overdrive and unrestrained adipose lipolysis drive alcohol-induced hepatic steatosis in rodents. Mol Metab. 2023 Sep 29;78:101813. PMID: 39437790.
• Grant LK, Coborn JE, Cohn A, Nathan MD, Scheer FAJL, Klerman EB, Kaiser UB, Harder J, Abramson M, Elguenaoui E, Russell JA, Wiley A, Rahman SA, Joffe H. Sleep Fragmentation and Estradiol Suppression Decrease Fat Oxidation in Premenopausal Women. J Clin Endocrinol Metab. 2022 Jul 14;107(8):e3167-e3176. doi: 10.1210/clinem/dgac313. PMID: 35569055; PMCID: PMC9282266.
• Kim H, Shah K, Buettner C. Use of Patient-Reported Outcomes for Assessing Diabetes Outcomes. Endocrinol Metab Clin North Am. 2022 Dec;51(4):781-793. doi: 10.1016/j.ecl.2022.05.001.
• Shah A, Wang Y, Wondisford FE; Differential Metabolism of Glycerol Based on Oral and Intravenous Administration in Humans, Metabolites; 2022; 12:890.
• Cohen DA, Ricotta DN, Parikh PD. Things we do for no reason™: Routinely holding metformin in the hospital. J Hosp Med. 2022 Mar;17(3):207-210. doi: 10.12788/jhm.3644. PMID: 34424186.
• Sullivan AM, Beltran CP, Ranchoff BL, Hayes MM, Atkins KM, Tibbles CD, Cohen AP, Cohen DA, Huang GC, Schwartzstein RM; Clinician Educator Research Group. Enhancing Clinical Teaching in Critical Thinking, High-Value Care, and Health Care Equity. J Contin Educ Health Prof. 2022 Jul 1;42(3):164-173. doi: 10.1097/CEH.0000000000000441. PMID: 36007516.
• Bassin SR, Kohm K, Fitzgerald N, Cohen DA. An Assessment of Nutrition Education in Endocrinology Fellowship Programs in the United States. Endocr Pract. 2022 Mar;28(3):310-314. doi: 10.1016/j.eprac.2021.12.012. Epub 2021 Dec 26. PMID: 34965450.
• Cohn A, Nehs M, Chan J, Vaidya A. Casting a Wide Net. N Engl J Med. 2021 Apr 1;384(13):e50. doi: 10.1056/NEJMimc2028852. PMID: 33789015.
• Watari J, Vekaria S, Lin Y, Patel M, Kim H, Kang F, Lubitz S, Beninato T, Laird AM. Radiology report language positively influences adrenal incidentaloma guideline adherence. Am J Surg. 2022 Feb;223(2):231-236. doi: 10.1016/j.amjsurg.2021.06.015. Epub 2021 Jun 29. PMID:34243951.
• Scherer T, Sakamoto K, Buettner C. Brain insulin signalling in metabolic homeostasis and disease. Nat Rev Endocrinol. 17:468-488-483; 2021. PMID: 34108679.
• Bassin SR, Amorosa L. Prophylactic Antithyroid Treatment Prior to Contrast Imaging in Hyperthyroid Patients. Endocr Pract. 2021 Jul;27(7):757-759. doi: 10.1016/j.eprac.2021.03.003. Epub 2021 Mar 9. PMID: 33711486.

• USMLE steps
• ABIM board certified or board eligible
• NJ license (limited license if on visa)
• A valid ECFMG certificate for all foreign medical graduates
• Completion of a prior internal medicine residency

• Michelle Sheyman, MD - Assistant Professor of Medicine, Zucker School of Medicine at Hofstra Northwell Health, NY
• Carlos Rivera, MD - Assistant Professor of Medicine, University of Arizona Banner Health, AZ
• Maryam Bojarian, MD - Assistant Professor of Medicine, New York Medical College Westchester Medical Center, NY
• Tiffany Purewal, MD - Private Practice, San Antonio, TX
• Mina Botros, MD - Assistant Professor of Medicine, Zucker School of Medicine at Hofstra Northwell Health, NY
• Iqra Farooqi, MD - Private Practice, FL
• Mangaiyarkkarsi Sivakumar, MD - Private Practice, NJ
• Manthan Pandya, MD - Division Chief of Endocrinology, Trinitas Regional Medical Center, NJ
• Niharika Yedla, MD – Clinical Instructor, Southern Illinois University, Quincy, IL
• Chukwuka Akamnonu, MD - Private Practice, Glendale, CA
• Sahil Parikh, MD - Private Practice, Los Angeles, CA
• Julie Zaidan, MD - Assistant Professor, Donald and Barbara Zucker School of Medicine at Hofstra Northwell Health, NY
• Abeera Khan, MD - AtlantiCare, Egg Harbor, NJ
• Najaf Asrar, MD - Private Practice, North Brunswick, NJ
• Juman Takeddin, MD - Private Practice, Raleigh, NC
• Sima Patel, MD - Lead Scientific Director Medical Affairs North America, Recordati Rare Diseases, NJ
• Navinder Jassil, MD - Assistant Professor of Medicine at Cooper Medical School at Rowan University, NJ
• Garima Thapar, MD - Private Practice, Voorhees, NJ
• Lissette Cespedes, MD – Medical Director Global Medical Affairs Rare Disease, Pfizer, NY
• Jorge Vivar Aguirre, MD - Private Practice, Salisbury, MD
• Pegah Yousefzadeh, DO - Private Practice, Lake Success, NY
• Lyudmila Shvets-Gabriel, MD - White Plains Hospital Physician Associates, NY
• Amy Chow, MD - UCLA Health, Thousand Oaks, CA
• Anupa Sharma, DO – Section Chief of Endocrinology, Penn Medicine Princeton Health; Clinical Assistant Professor of Medicine at Rutgers Robert Wood Johnson Medical School, NJ

We study the role of the SNS in the regulation of adipose tissue and liver function and mechanisms through which chronic dysregulation of catecholamine levels and sympathetic outflow to peripheral metabolic organs can contribute to insulin resistance, hyperglycemia, and systemic inflammation. To this aim, we are developing novel methods to monitor SNS activity in peripheral metabolic organs in real time in vivo and have developed inducible loss of function models to study the function of the SNS.

We are characterizing the physiological role of hypothalamic inflammation in metabolic homeostasis, specifically the role of microglia, the gut-brain axis, and interferon gamma in counterregulation. We aim to determine to what extend dysregulation of counterregulatory mechanisms contributes to insulin resistance in obesity and diabetes.

The aim of this project is to study the effect of TBI-induced neuroinflammation in the CNS control of peripheral metabolism as well as the contribution of metabolic dysregulation to chronic neuroinflammation in TBI.

As AD is increasingly understood as a neuroinflammatory disease with possibly important metabolic drivers, we wish to examine the role of adipose tissue function and lipotoxicity and brain insulin signaling on cognition and neuroinflammation.

Circadian rhythms regulate many biological processes such as metabolism and cognition. We are interested to understand how the central clock synchronizes with peripheral clocks, if light exposure can be used to reentrain circadian rhythms in both rodents and humans and if this improves metabolism and cognition.

Dr. Buettner is currently conducting a clinical study to determine whether a long-term tailored light intervention that promotes entrainment can improve sleep disturbances, inflammation, insulin sensitivity, glucose disposal, and cognition in patients with mild cognitive impairment.

The aim of this project is to study the effect of TBI-induced neuroinflammation in the CNS control of peripheral metabolism as well as the contribution of metabolic dysregulation to chronic neuroinflammation in TBI. Based on our finding that rodents develop impaired glucose homeostasis after TBI, we are currently conducting a retrospective chart review in collaboration with the Icahn School of Medicine at Mount Sinai to determine the incidence of prediabetes and diabetes in patients with a history of TBI and thus determine the translational relevance of our findings in rodents.

Preclinical studies in Dr. Buettner’s lab have shown that certain antibiotics, which alter the gut microbiome composition and modulate the inflammatory environment in the hypothalamus, lead to impaired glucose counterregulation to hypoglycemia or neuroglycopenia. The purpose of this study is to assess the translational relevance of our findings in rodents and investigate the association between specific antibiotics and the risk of hypoglycemia in the inpatient population at RWJMS.

To assess energy homeostasis, including oxygen consumption, CO2 production, respiratory exchange ratio through indirect calorimetry, and food intake and activity monitoring.

The core can perform indirect calorimetry for up to 24 animals in parallel (8 Comprehensive Laboratory Animal Monitoring System (CLAMS, Columbus Instruments) and 16 TSE metabolic cages). Eight of these indirect calorimetric cages are placed in one environmental chamber that allows the manipulation of the ambient temperature where the animals can be housed at a set temperature in a range from 4°C to 30°C to assess how metabolism is regulated during cold exposure or thermoneutrality commonly believed to be around 28°C.

The latter is important as the ambient temperature influences many metabolic functions, and the argument has been made that mice are under constant moderate cold stress at room temperature, which changes the susceptibility to fatty liver and metabolic disease. Hence, conventionally housed mice are not a good model for human disease since humans wear clothes and do not experience cold stress.

Thus, it is informative to study mice at thermoneutrality as a more suitable model for human conditions, which the environmental chamber allows. The profound impact of ambient temperature on experimental outcomes is now appreciated in the metabolism and, for example, in the immunology field.

The lean and fat mass ratio is critical to studying/understanding energy homeostasis and metabolic disease. The EchoMRI uses MRI to measure lean mass, fat mass, and free water content in restrained conscious mice. Body composition is assessed without anesthesia in less than three minutes. This can be repeated to confirm reproducibility and serially monitored for the effect of an obesity or drug treatment and/or specific gene ablation in metabolic control.

To determine metabolic flux and the turnover rate of specific molecules and the contribution of labeled substrates to metabolism and metabolic control, the core provides metabolomics analysis using stable-isotope labeled tracer infusion and LC/MS. Tracers are infused through the right jugular vein to establish and maintain a steady state for 6h, and serum samples are collected and derivatized to analyze with LC/MS (Metabolomics Core conducts LC/MS).

Enrichment of metabolites and flux analysis is conducted to determine the distribution of specific carbon sources and the turnover rate of metabolites. These results provide fundamental metabolic information in diabetes, NAFLD, cardiovascular disease, and cancer. Metabolomics analysis is a critical technique to overcome the limitation of traditional metabolomics studies such as bolus injection because infusion maintains a steady state of metabolism, and state of the art LC/MS system enables determination of the enrichment and flux rate of many metabolites in the same sample.

The core provides a hyperinsulinemic-euglycemic clamp using a stable-isotope labeled 6,6-D2 glucose infusion and LC/MS to study glucose metabolism and insulin action in mice. 6,6-D2 glucose is infused through the right jugular vein for 3h for basal clamp and then 6,6-D2 glucose plus insulin and 50% (w/v) glucose are infused for 3h to maintain euglycemia. The serum is collected to determine glucose enrichment and turnover rate using LC/MS.

This result provides key parameters of insulin action such as the glucose infusion rate and the rate of hepatic glucose production in the basal state and the hyperinsulinemic clamp period. Hyperinsulinemic euglycemic clamp in this core uses a stable-isotope labeled tracer instead of traditional radioisotope and LC/MS, providing more accurate results and a safer methodology as no radioactivity is involved.

Our most popular service. Covers central metabolites including glycolytic intermediates, TCA cycle compounds, amino acids, nucleotides, and their derivatives. Specificity is achieved through the combination of chromatographic separation and high-resolution MS, with MS/MS used in selected cases to differentiate isomers. Current methods cover approximately 300 water-soluble metabolites, each identified by retention time match to synthetic standards. For researchers primarily interested in central carbon metabolism, it is common to analyze only anionic metabolites (carboxylic acids and phosphorylated compounds), which can be achieved with a single LC-MS run in negative ionization mode. To also cover cationic metabolites like acyl-carnitines, methyl-nicotinamide, and acetyl-polyamines, users may elect to also run in positive ionization mode. Stable isotope labeling patterns can also be routinely measured (13C, 15N, 2H, etc.).

Identification and quantitation of non-polar metabolites by LC-MS, with the coverage of approximately 600 lipids spanning all major classes, including cholesteryl ester, mono, di- and tri-acylglycerides, phosphatidylserine, phosphatidylcholine, sphingomyelin, ceramide, etc.

The analytical methods used for metabolite quantitation are untargeted: They measure all ions present in the sample. From these measurements, we routinely quantitate only known analytes, because most users are focused on the abundances and labeling of these classical species (like glutamate, malate, GABA, etc.). While there are a very large number of other peaks, most reflect analytical artifacts, not metabolites. Nevertheless, the discovery of new cancer-associated metabolites is a great scientific opportunity, born out by the clinical importance of 2-hydroxyglutarate. Online tools (XCMS, MzMine3, GNPS) and commercial software (CompoundDiscoverer) enable us to find unexpected peaks that go up or down in a particular set of samples. The shared resource then works with users to identify the underlying metabolites. To this end, the Metabolomics Shared Resource is developing novel strategies for metabolite identification based on combining isotope labeling and MS/MS.

Investigators planning to conduct research using the Metabolomics Shared Resource are encouraged to submit an experimental plan describing the biological question and protocol design. Users are guided to detailed SOPs for critical steps like sample harvesting and metabolite extraction. Given the unique requirements of many projects, Metabolomics personnel are available to meet with investigators at the inception of the project. Consultation regarding experimental design is also routinely provided prior to grant submission. After sample analysis, experimental data is provided to the investigator along with suggestions for interpretation. Additional experiments may be planned with the investigator to optimize the results. In addition, the Metabolomics shared resource offers seminars and presentations by internal and external experts. It trains users in the Metabolomics Analysis and Visualization Engine (MAVEN) software package for data processing and visualization. To facilitate the training of graduate students and postdocs, professional staff manually review the LC-MS raw data of less experienced users, to ensure accurate processing and interpretation. Facility staff members also routinely manually check all data associated with key biological discoveries.