Endocrinology Fellowship Faculty & Specialties

NIH faculty is dedicated to training endocrine fellows in the clinical and scientific basis of endocrine physiology and disease. Experts in various divisions work directly with fellows on patient care and in collaboration during rounds and conferences. A list of participating NIH Institutes and faculty is provided below.

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

Diabetes, Endocrinology and Obesity Branch

The Diabetes, Endocrine, and Obesity Branch conducts clinical and basic research in the area of diabetes, insulin resistance, thyroid physiology and pathology, metabolism, and body weight regulation. Investigators study and treat patients with extreme insulin resistance, lipodystrophy, hypoglycemia, acromegaly and other disorders of carbohydrate and lipid metabolism. Studies of pancreatic islet biology, neuroendocrinology and immune modulation are conducted. Using the tools of the metabolic clinical research units, energy expenditure and thermoregulation are explored. Additionally, disorders of thyroid growth and function are studied providing clinical experiences in the treatment of thyroid nodules and cancer.


  • Dr. Marc Reitman, Chief, Diabetes, Endocrinology and Obesity Branch, is interested in the mechanisms underlying energy homeostasis including metabolic rate and body temperature regulation, brown adipose tissue physiology, drug treatments for obesity, and BRS-3 (bombesin receptor subtype-3).
  • Dr. Ranganath Muniyappa, Program Director, studies of the metabolic and vascular actions of insulin and how these actions are impaired in insulin-resistant states such as obesity, diabetes, and cardiovascular disease.
  • Dr. Rebecca Brown, Lasker Tenure Track Investigator, conducts research related to the pathophysiology and clinical therapeutics for rare disorders of extreme insulin resistance including lipodystrophy, mutations of the insulin receptor, and autoimmune conditions affecting insulin signaling.
  • Dr. Aaron Cypess, Acting Section Chief, Translational Physiology Section, whose current translational research projects in the lab focus on brown and white adipose tissue function, energy balance, clinical physiology, and imaging.
  • Dr. Anne Sumner, Section Chief, Section on Ethnicity and Health.
  • Dr. Lynnette K. Nieman, works on disorders of cortisol insufficiency and excess. Recent studies include an evaluation of the best imaging techniques to identify ectopic ACTH-producing tumors, and the utility of free cortisol and aldosterone measurement in the diagnosis of adrenal insufficiency.
  • Dr. Simeon Taylor, Distinguished Investigator, Special Volunteer, conducts clinical and translational research related to pharmacotherapy of metabolic disease - with a special emphasis on genetic factors that predict an individual patient's response to specific drugs (i.e., Precision Medicine).
  • Dr. Marissa Lightbourne, conducts transitional care research, investigating cardiometabolic and insulin resistance changes in endocrine disease states in children transitioning to adults. She works collaboratively with other investigators in areas such as sex chromosome abnormalities, pathophysiology of insulin resistance and early cardiometabolic markers. For NICHD, she is co-chief of the internal medicine, endocrinology, and genetics inpatient ward and outpatient endocrinology and faculty for pediatric and adult endocrinology.

Metabolic Diseases Branch

This Metabolic Diseases Branch sees patients with disorders of calcium metabolism and metabolic bone disease, including sporadic and familial forms of primary hyperparathyroidism (e.g., Multiple Endocrine Neoplasia Type 1). Other patients include those with various forms of parathyroid hormone resistance and hypocalcemia.


  • Dr. Lee Weinstein, Chief, Signal Transduction Section, studies the pathogenesis and treatment of Albright hereditary osteodystrophy, pseudohypoparathyroidism, and related disorders. He also studies animal models to examine the regulation and role of G proteins in metabolism and hormone action.
  • Dr. William Simonds, Chief, Endocrine Signaling & Oncogenesis Section, studies clinical and basic scientific aspects of familial isolated hyperparathyroidism, parathyroid cancer, and the hyperparathyroidism-jaw tumor syndrome, as well as the function of the G protein beta5/R7-RGS/ R7BP signaling complex expressed in neurons and endocrine tissue.
  • Dr. Klubo-Gwiezdzinska, Principal Investigator in Thyroid Nodules and Thyroid Cancer Program, whose scientific interest involves translational and clinical studies focused on optimization of thyroid cancer diagnosis and therapy, aimed at improving patients’ morbidity and mortality.
  • Dr. Smita Jha, Director, Bone & Mineral Disorders Research is an endocrinologist interested in genetic disorders of bone and mineral metabolism particularly a) familial hyperparathyroidism including familial hypocalciuric hypercalcemia, multiple endocrine neoplasia type 1 and hyperparathyroid jaw tumor syndrome b) pseudohypoparathyroidism and related disorders and c) Jansen's metaphyseal chondrodysplasia.

Digestive Disease Branch

The Digestive Diseases Branch conducts clinical and laboratory research on the normal and pathological structure and functions of the esophagus, stomach, small and large intestine, pancreas, and liver.

  • Dr. Mark A. Levine, Chief, The Molecular and Clinical Nutrition Section, examines how specific nutrient function occurs in relation to nutrient concentration, in vitro (in cells and organelles) and in vivo (animals and people). His work focuses on a functional basis for nutrient recommendations, rather than reliance on preventing deficiency, which agencies have used for many years.
  • Dr. Ifechukwude Ebenuwa, Assistant Research Physician, The Molecular and Clinical Nutrition Section.

Office of the Clinical Director

  • Dr. Sanaz Sakiani, Associate Program Director. Dr. Sakiani is an adult endocrinologist and staff clinician at the NIDDK. Her interests are in the treatment of patients with type 2 diabetes and other general endocrine disorders.

National Institute of Child and Health Development (NICHD)

The investigators below seek to understand the genetic and molecular mechanisms leading to disorders that affect the adrenal cortex, with emphasis on those that are hereditary and associated with multiple tumors and abnormalities in other endocrine glands (i.e. the pituitary gland) and tissues of neuroectodermal origin (i.e. the melanocytes).


  • Dr. Karel Pacak, Chief, Section on Medical Neuroendocrinology, conducts research designed to elucidate the molecular genetic, biochemical and imaging bases for the clinical manifestations, laboratory findings, responses to treatment, and prognosis of patients harboring adrenal and extra-adrenal pheochromocytoma.
  • Dr. Jack A. Yanovski, Ph.D., M.D., NICHD, Chief of the Section on Growth and Obesity in the Division of Intramural Research.

Reproductive Medicine


  • Dr. Alan H. DeCherney, Deputy Clinical Director for Academic Affairs and Program Director of the Reproductive Endocrinology and Infertility fellowship training program, conducts research regarding all aspects of infertility both male and female including In vitro- fertilization, fertility preservation and rare diseases associated with fertility impairment, basic gamete efficiency and, in the Epidemiology Branch, population based studies in regard to fertility.

National Institute of Dental and Craniofacial Research (NIDCR)

Craniofacial and Skeletal Diseases Branch


  • Dr. Michael Collins, Chief, Section on Skeletal Disorders and Mineral Homeostasis; Director, Career Development and Research Training, research focuses on understanding of bone and mineral metabolism through clinical and translational studies of human diseases, and animal models and in vitro systems.
  • Dr. Rachel Gafni, Senior Research Physician and Head, Mineral Homeostasis Studies Group, studies bone and mineral disease with a focus on rare disorders of calcium and phosphate metabolism.
  • Dr. Allison Boyce, Head, FD/MAS Studies Group, researches rare and congenital disorders of mineral metabolism, with a particular emphasis on the rare bone and endocrine disorder fibrous dysplasia/McCune-Albright syndrome.
  • Dr. Kelly Roszko is an adult endocrinologist who researches bone and mineral metabolism particularly diseases relating to FGF23 and hypoparathyroidism.

National Institute of Environmental Health Sciences (NIEHS)

Clinical Research Branch


  • Dr. Janet Hall, Clinical Director and Head of the Reproductive Physiology and Pathophysiology Group. Hall is an internationally known clinician and clinical investigator. She studies the mechanisms involved in the integrated control of the reproductive system in women and its disruption in reproductive disorders.
  • Dr. Skand Shekhar, Assistant Research Physician with a special interest in studying the relationship between metabolism and reproductive disorders.
Last Reviewed August 2023