Jacqueline Jonklaas, MD, PhD, MPH

Jacqueline Jonklaas, MD, PhD, MPH

Assistant Professor
Division of Endocrinology and Medicine
Department of Medicine
Georgetown University Medical Center
Suite 232, Building D
3900 Reservoir Road, NW
Washington, DC 20007 
Phone: 202 687-2818
Fax: 202 687-2040 

Research Interests

Treatment of thyroid diseases, optimization of outcomes in thyroid cancer

Research Summary 

One ongoing five-year project involves monitoring clinical and biochemical indices of hypothyroidism on different T4/T3 replacement regimens, in comparison with traditional T4 treatment. The results from these clinical studies will have a significant impact on women’s health, as both hypothyroidism and thyroid cancer are more prevalent in women. Optimization of therapy for hypothyroidism is critical not only for the health of the individual, but also for optimization of fertility and pregnancy outcomes. With respect to thyroid cancer, 60% of the estimated deaths from thyroid cancer in 2003 are predicted to occur in women, again making this an important sex-specific health issue.

There has been considerable debate as to whether T4 replacement alone provides adequate replacement for hypothyroid patients. Studies addressing this issue have resulted in inconclusive results, and have been limited by the short duration of action of currently available T3 preparations. This study includes a placebo-controlled assessment of the response to combination therapy with T4 and T3. In addition, testing of a new sustained release T3 preparation is also planned. A second prospective study involves examining outcomes in thyroid cancer. Current thyroid cancer management includes thyroid surgery, radioactive iodine treatment, and use of thyroid hormone to suppress TSH levels. The individual impact of each of these modalities on disease progression and survival has been difficult to assess due to the absence of long-term, randomized clinical trials. However, the effect of these treatments on thyroid cancer outcomes is currently being evaluated by our multi-center registry, which is continuing to accrue patients. Radioactive iodine treatment is known to be a very valuable tool for the treatment of thyroid cancer. De-differentiated thyroid carcinomas, which have lost their ability to take up radioactive iodine, are particularly resistant to therapy. The registry also has studies examining the effect of several chemotherapeutic agents, such as decitabine, on de-differentiated thyroid cancers, which have lost their ability to take up radioactive iodine.

Representative Publications

  • Wong, L.L., Ewing, C.A. Jonklaas, J., Immunohistochemically demonstrated micrometastases to lymph nodes in papillary thyroid cancer. Endocrine Society Meeting, June 2001.
  • Jonklaas, J., Sarlis, N.J., Litofsky, D., Cooper, D.S., Ain, K., Bigos, S., Brierley, J., Haugen, B., Kim, P, Ladenson, P, Marks, P., Robbins, J., Skarulis, M., Maxon, H., Sherman, S.I. Both Near-total/Total Thyroidectomy (NTT) and Thyroid Hormone Suppression Therapy (THST) Improve Survival of Patients with Papillary Thyroid Carcinoma. American Thyroid Association Meeting, November 2001.
  • Bowen-Wright, H, Malezadeh, S, Jonklaas, J. Ectopic Intra-tracheal thyroid tissue presenting as new onset asthma. American Thyroid Association Meeting, October 2002.
  • Greene, C, Chen, L, Grekova, M, Connelly, D, Crusio, R, Rose, C, Saunders, C, Crayton, H, Jonklaas, J, Chutkan, R. Richert, J. A new gene overexpressed in multiple sclerosis immune cells. American Society for Biochemistry and Molecular Biology, FASEB, Spring, 2003.