Department of Medicine
Faculty Profiles by Division

Division of Endocrinology and Metabolism

Faculty Profiles

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photo Mara J Horwitz, MD

Endocrinology and Metabolism

Associate Professor of Medicine

Deputy Director of the Office of Research Protections

Associate Research Integrity Officer

Conflict of Interest Committee Vice-Chair for the University of Pittsburgh


Phone: 412-586-9700

Office: 580 Falk Clinic
3601 Fifth Ave.
Pittsburgh, PA 15213
Phone: 412-586-9700
Fax: 412-586-9726
Administrative Assistant:
Emily Welsh
Address: W1026 Biomedical Science Tower
200 Lothrop Street
Pittsburgh, PA 15213
Phone: 412-648-9770
Fax: 412-648-3290
Education and Training
BA, Northwestern University, 1983
MD, Columbia University, College of Physicians & Surgeons, 1987
Internship, Internal Medicine, University of Pittsburgh Medical Center, 1988
Residency, Internal Medicine, University of Pittsburgh Medical Center, 1990
Fellowship, Endocrinology and Metabolism, University of Pittsburgh Medical Center, 1993
Research Interest
Dr. Horwitz is a clinical metabolic bone researcher with a primary interest in the interaction of parathyroid hormone (PTH) and parathyroid hormone-related peptide (PTHrP) on mineral homeostasis, the skeleton, and vitamin D metabolism. This work has evolved to include NIH-sponsored clinical studies in osteoporosis, humoral hypercalcemia of malignancy, and hyperparathyroidism as well as lactation and its calcitropic/skeletal biology in both Caucasians and African-Americans. Dr. Horwitz has also collaborated on numerous osteoporosis and epidemiology studies with epidemiologists at the University of Pittsburgh Graduate School of Public Health.
Clinical Interest
Dr. Horwitz is a metabolic bone specialist with a practice that includes evaluation and treatment of osteoporosis, hyperparathyroidism and hypoparathyroidism, phosphorous disorders, Paget's disease, as well as other calcium and metabolic bone diseases.
Educational Interest
Dr. Horwitz takes an active role in teaching medical students, residents and fellows in all aspects of metabolic bone disease through both formal lectures and clinical precepting. She has mentored many clinical fellow research projects which have led to both publications and national meeting presentations. In recent years, she has taken on an administrative and educational role in research compliance as the Deputy Director of the Office of Research Protections, the Associate Research Integrity Officer and the Conflict of Interest Committee Vice-chair for the University.
For my complete bibliography, Click Here.
Selected Publications:
Horwitz, M. J. Hypercalcemia of Malignancy: Mechanisms. Up to Date. 2020; Basow DS (Ed): Waltham,MA.
Horwitz, M. J. Non-parathyroid Hypercalcemia. Primer on the Metabolic Bone Diseases and Disorders of Mineral Metabolism, 9th Edition. 2019; The Society for Bone and Mineral Research: InFavusMF(ed.),WashingtonDC.
Horwitz, M. J., Stewart, A. F. Metabolic Bone Disorders. CECIL Essentials of Medicine, 9th edition. 2016; Wb Saunders Company, Philadelphia: 750-757.
Augustine, M., Horwitz, M. J. Parathyroid Hormone and Parathyroid Hormone-related Protein Analogs as Therapies for Osteoporosis. Curr Osteoporos Rep. 2013; 11(14): 400-406.
Horwitz MJ, Augustine M, Kahn L, Martin E, Oakley CC, Carneiro ROM, Tedesco MB, Laslavic A, Serieka SM, Bisello A, Garcia-Ocana A, Gundberg CM, Cauley JA, Stewart AF. A Comparison of Parathyroid Hormone-related Protein (1-36) and Parathyroid Hormone (1-34) on Markers of Bone Turnover and Bone Density in Postmenopausal Women: The PrOP Study. J Bone Miner Res. 2013; in press.
Carneiro, R. M., Prebehala, L., Tedesco, M. B., Sereika, S. K., Gundberg, C. M., Horst, R. L., Stewart, A. F., Horwitz, M. J. Evaluation of markers of bone turnover during lactation in African-Americans: a comparison with Caucasian lactation. J Clin Endocrinol Metab. 2013; 98(2): 523-32.
Barbour, K. E., Zmuda, J. M., Boudreau, R., Strotmeyer, E.S., Horwitz, M.J., Evans, R.W., Kanaya, A.M., Harris, T.B., Cauley, J.A., The Health ABC Study. The effects of adiponectin and leptin on changes in bone mineral density. Osteoporosos Int. 2012; 23(6): 1699-710.
Caulay JA, Danielson ME, Boudreau R, Barbour KE, Horwitz MJ, Bauer DC, Ensrud KE, Manson JE, Wactawski-Wende J, Shikany JM, Jackson RD. Serum 25-hydroxyvitamin D and clinical fracture risk in a multiethnic cohort of women: the Women's Health Initiative (WHI). J Bone Miner Res. 2011; 26(10): 2378-88.
Horwitz MJ, Tedesco MB, Sereika SK, Prebehala L, Gundberg CM, Hollis BW, Bisello A, Carneiro RM, Garcia-Ocana A, Stewart AF. A 7-day continuous infusion of PTH or PTHrP suppresses bone formation and uncouples bone turnover. J Bone Miner Res. 2011; 26(9): 2287-97.
Carneiro RM, Prebehalla L, Tedesco MB, Sereika SM, Hugo M, Hollis BW, Gundberg CM, Stewart AF, Horwitz MJ. Lactation and bone turnover: a conundrum of marked bone loss in the setting of coupled bone turnover. J Clin Endocrinol Metab. 2010; 95(4): 1767-76.
Notable Achievements
Member, Editorial Board, Journal Clinical Endocrinology and Metabolism, 2014-2017
Invited Symposium Speaker, The 97th Meeting of The Endocrine Society, 2015