Caroline Messer, MD

Double-board certified endocrinology in New York

Dr. Caroline Messer is a double-board certified endocrinologist who sees patients at two New York locations: on Fridays at Well by Messer and on Mondays, Tuesdays and Wednesdays at Fifth Avenue Endocrinology. The site advises that, when booking an appointment, you carefully check the practice name and corresponding address, as care is provided across both locations.

The doctor maintains several thousand active patients and, according to her presentation, is known for respecting appointment times and returning calls promptly. Her practice covers a broad spectrum of endocrinology, with a particular interest in preventive care.

Academic background and credentials

She completed a fellowship in Endocrinology, Diabetes and Metabolism at Mount Sinai Hospital, where she also completed her residency in Internal Medicine. She earned her medical degree from the Mount Sinai School of Medicine and completed her undergraduate studies at Yale University.

She is board certified in Internal Medicine and in Endocrinology, Diabetes and Metabolism. She also holds certifications in clinical densitometry and endocrine neck ultrasound (ECNU). She maintains hospital privileges at the Mount Sinai School of Medicine in New York, where she is a Clinical Assistant Professor, and is an Assistant Professor at the Hofstra School of Medicine, also in New York.

Areas of care

The practice treats both the most prevalent endocrine conditions and less common ones. Among the medical specialties listed are:

• Adrenal adenomas (adrenal masses) and congenital adrenal hyperplasia
• Amenorrhea and oligomenorrhea (absent or infrequent menstrual periods)
• Initiation and cessation of breastfeeding
• Cushing's disease (elevated cortisol levels)
• Gynecomastia (breast formation in males)
• Hyperaldosteronism (elevated aldosterone)
• Hypercalcemia and hypocalcemia (high and low calcium)
• Hyperlipidemia (high cholesterol)
• Hyperparathyroidism (elevated parathyroid hormone)
• Hypoglycemia (low blood glucose) and hyponatremia (low sodium)
• Difficulty losing weight
• Thyroid cancer and thyroid nodules, hyperthyroidism and hypothyroidism
• Type 1, type 2 and gestational diabetes
• Osteopenia and osteoporosis
• Pheochromocytoma (elevated adrenaline)
• Pituitary adenomas (pituitary masses)
• Polycystic ovary syndrome
• Prolactinomas (elevated levels of the hormone that produces breast milk)
• Gender-affirming hormone treatment

Career and research

Dr. Messer has published articles in journals such as Endocrine Practice, Pituitary and Clinical Medicine: Therapeutics, among others, on topics including pancreatic beta-cell dysfunction in polycystic ovary syndrome, thyroid disease in pregnancy and male hypogonadism. She is a co-author of chapters in the Oxford American Handbook of Endocrinology and Diabetes (2010).

In the field of research, she has participated as a sub-investigator in a Novartis pasireotide study and as principal investigator in the Toujeo Achieve Control trial, both since July 2015. At the Mount Sinai School of Medicine she was a researcher in the Department of Endocrinology between 2009 and 2010, where she led a study on metformin and received a $15,000 Marilyn Fishman grant for diabetes research in 2009. Between 1998 and 2004 she conducted research in the Department of Immunology on the effects of intestinal epithelial membrane glycoprotein gp180 on CD8+ and CD4+ T lymphocytes.

Memberships and outreach

She belongs to the Endocrine Society and the American Association of Clinical Endocrinology. She has given numerous talks and presentations, including Endocrinology Grand Rounds sessions at Weill Cornell (2019), presentations at the Pri-Med East conference on Basaglar (2017) and on SGLT2 inhibitors (2013), and a presentation at the Endocrine Society annual meeting on Graves' disease and thymic hyperplasia (2015). She has also appeared in media such as Fox News and NBC's LX New York, and in lecture series on thyroid and osteoporosis at Mount Sinai and Northern Westchester Hospital.

Practice approach

Dr. Messer describes her practice as a balance between scientific evidence and sustained listening to the patient. She notes that she reduced her patient volume from 25 to 30 patients per day at her busiest to between 10 and 15 per day, with the goal of dedicating more time to each medical history. She mentions that she sees patients continuously for more than fifteen years, some of whom have followed her from Westchester and Lenox Hill to her private practice.

She dedicates part of her work to patients from underserved communities without charging fees, and on weekends she distributes food with her family at various community centers in the Bronx. She also organizes the annual family service day at her children's school and collaborates with Jewish and Israeli non-profit organizations.