Department of Medicine
Faculty Profiles by Division

Division of Endocrinology and Metabolism

Faculty Profiles

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photo Mara J Horwitz, MD

Associate Professor of Medicine


Phone: 412-586-9700

Office: 580 Falk Clinic
3601 Fifth Ave.
Pittsburgh, PA 15213
Phone: 412-586-9700
Fax: 412-586-9726
Administrative Assistant:
Chelsea Dempsey
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. Most recently, she has expanded her educational role to the Research Conduct and Compliances Offices at the University of Pittsburgh where she plays both an educational and advisory role.
For my complete bibliography, Click Here.
Selected Publications:
Wesseling-Perry K, Harkins GC, Wang HJ, Elashoff R, Gales B, Horwitz MJ, Stewart AF, Jüppner H, Salusky IB. The calcemic response to continuous parathyroid hormone (PTH)(1-34) infusion in end-stage kidney disease varies according to bone turnover: a potential role for PTH(7-84). J Clin Endocrinol Metab. 2010; 95(6): 2772-80.
Barbour KE, Zmuda JM, Strotmeyer ES, Horwitz MJ, Boudreau R, Evans RW, Ensrud KE, Petit MA, Gordon CL, Cauley JA; Osteoporotic Fractures in Men (MrOS) Research Group. Correlates of trabecular and cortical volumetric bone mineral density of the radius and tibia in older men: the Osteoporotic Fractures in Men Study. J Bone Miner Res. 2010; 25(5): 1017-28.
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.
Horwitz MJ, Tedesco MB, Garcia-Ocaña A, Sereika SM, Prebehala L, Bisello A, Hollis BW, Gundberg CM, Stewart AF. Parathyroid hormone-related protein for the treatment of postmenopausal osteoporosis: defining the maximal tolerable dose. J Clin Endocrinol Metab. 2010; 95(3): 1279-87.
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.
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. What Medical Options Should be Considered for the Treatment of Primary Hyperparathyroidism?. Clinical Endocrinology. 2011; 75(5): 592-5.
Augustine M, Horwitz MJ. Hypocalcemia. Clinical Decision Support: Endocrinology. 2012; In Press.
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 RM, Prebehala L, Tedesco MB, Sereika SK, Gundberg CM, Horst RL, Stewart AF, Horwitz MJ. Differential effects of lactation on mineral metabolism in African-Americans vs. Caucasians. J Clin Endocrinol Metab. 2013; 98(2): 523-32.
Sponsored Research/Activities
Title: University of Pittsburgh CTSI Admin Supplement - Enhancing Clinical Research Professionals Training and Qualifications
Role: Co-Investigator
Funding Agency: National Center for Advancing Translational Sciences
Grant Number: UL1 TR000005
Start Year: 2014
End Year: 2016
Title: Testosterone Trial Bone Subset
Role: Co-Investigator
Funding Agency: University of Pennsylvania/National Institute of Aging
Start Year: 2011
End Year: 2015
Title: Testosterone Trial
Role: Co-Investigator
Funding Agency: University of Pennsylvania/National Institute of Aging
Grant Number: U01 AG030644
Start Year: 2009
End Year: 2015
Notable Achievements
Member, Editorial Board, Journal Clinical Endocrinology and Metabolism, 2014-2017
Invited Symposium Speaker, The 97th Meeting of The Endocrine Society, 2015