Hypothyroidism — Is Levothyroxine Alone Adequate Thyroid Hormone Replacement?
Citation(s)
Hoefig CS, Kohrle J, Brabant G, Dixit K, Yap B, Strasburger CJ, Wu Z Evidence for extrathyroidal formation of 3-iodothyronamine in humans as provided by a novel monoclonal antibody-based chemiluminescent serum immunoassay. J Clin Endocrinol Metab. 2011 Jun;96(6):1864-72. doi: 10.1210/jc.2010-2680. Epub 2011 Apr 13.
Samuels MH, Schuff KG, Carlson NE, Carello P, Janowsky JS Health status, mood, and cognition in experimentally induced subclinical hypothyroidism. J Clin Endocrinol Metab. 2007 Jul;92(7):2545-51. doi: 10.1210/jc.2007-0011. Epub 2007 May 1. Erratum In: J Clin Endocrinol Metab. 2007 Oct;92(10):3966.
Saravanan P, Chau WF, Roberts N, Vedhara K, Greenwood R, Dayan CM Psychological well-being in patients on 'adequate' doses of l-thyroxine: results of a large, controlled community-based questionnaire study. Clin Endocrinol (Oxf). 2002 Nov;57(5):577-85. doi: 10.1046/j.1365-2265.2002.01654.x.
Interventional studies are often prospective and are specifically tailored to evaluate direct impacts of treatment or preventive measures on disease.
Observational studies are often retrospective and are used to assess potential causation in exposure-outcome relationships and therefore influence preventive methods.
Expanded access is a means by which manufacturers make investigational new drugs available, under certain circumstances, to treat a patient(s) with a serious disease or condition who cannot participate in a controlled clinical trial.
Clinical trials are conducted in a series of steps, called phases - each phase is designed to answer a separate research question.
Phase 1: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase 2: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
Phase 3: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Phase 4: Studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.
