Lipid Metabolism


Clinical Interests
  • Diabetes management
  • Endocrinology
  • Lipid disorders
Medical Education
  • MD, UC San Francisco School of Medicine
  • Residency, Massachusetts General Hospital
  • Fellowship, Massachusetts General Hospital
Board Certifications
  • Endocrinology
  • Diabetes & Metabolism
  • Internal Medicine
Foreign Languages
  • French
  • Boston: Massachusetts General Hospital
Insurances Accepted
  • Aetna Health Inc.
  • AllWays Health (NHP) - ACD
  • AllWays Health (NHP) - PBO
  • Beech Street
  • Blue Cross Blue Shield - Blue Care 65
  • Blue Cross Blue Shield - Indemnity
  • Blue Cross Blue Shield - Managed Care
  • Blue Cross Blue Shield - Partners Plus
  • BMC HealthNet Mass Health MCO/ACO
  • Cigna (PAL #'s)
  • Commonwealth Care Alliance
  • Fallon Community HealthCare
  • Great-West Healthcare (formally One Health Plan)
  • Harvard Pilgrim Health Plan - ACD
  • Harvard Pilgrim Health Plan - PBO
  • Health Care Value Management (HCVM)
  • Humana/Choice Care PPO
  • MassHealth
  • Medicare
  • Medicare - ACD
  • OSW - Maine
  • OSW - New Hampshire
  • Private Health Care Systems (PHCS)
  • Railroad Medicare
  • Railroad Medicare - ACD
  • Senior Whole Health
  • TriCare
  • Tufts Health Plan
  • Unicare
  • United Healthcare (non-HMO) - ACD
  • United Healthcare (non-HMO) - PBO
  • Well Sense Pediatrics

Note: This provider may accept more insurance plans than shown; please call the practice to find out if your plan is accepted.

Patient Age Group
Provider Gender


Dr. Freeman graduated from Harvard College and received his MD at the University of California, San Francisco in 1979. He served as an intern, resident and endocrinology fellow in the Department of Medicine at Massachusetts General Hospital and was Chief Resident in Medicine at Mass General in 1985.

Following clinical training, he worked as a post-doctoral research fellow in the Biology Department of the Massachusetts Institute of Technology before returning to Mass General to head the Cardiovascular Health Center. He became Chief of the Lipid Metabolism Unit at Mass General in 1992.

Dr. Maso?s research work has centered on the role of macrophages in atherosclerosis with particular interest in the trafficking of lipids through these cells. While at MIT, he and his colleagues cloned the first macrophage scavenger receptor. Over the years, his lab has studied the mechanisms of atherosclerotic foam cell formation and the impact of lipids on activation of vascular inflammatory responses. The lab has also made fundamental contributions to our understanding of reverse cholesterol transport via its work on the topology and biochemistry of the ABCA1 transporter, mutations in which cause Tangier disease.

In the last two years, the lab has expanded its interest to the other ABCA transporters, all of which appear to play a role in cellular lipid trafficking.Mason remains clinically active, teaching medical students, residents, and endocrine fellows rotating through Mass General clinical services and he continues to direct the Mass General Lipid Clinic that he founded in 1986.

News & Events

  • The Benefits of Lowering Cholesterol

    A Mass General endocrinologist discusses why patients should consider medications to lower their cholesterol and the role of genes and lifestyle.

  • Translational and Clinical Research Center opens

    Following the cutting of a ceremonial blue ribbon and an enthusiastic round of applause, the doors to the new MGH Translational and Clinical Research Center (TCRC) officially opened Nov. 30.


Lipid Metabolism Unit
55 Fruit Street
Boston, MA 02114-2696
Phone: 617-726-5906
Fax: 617-726-2879
Endocrine Associates
15 Parkman Street
Boston, MA 02114-3117
Phone: 617-643-5588
Fax: 617-724-2718