Study of Thyrotropin-Releasing Hormone in Normal Volunteers and in Patients With Thyroid or Pituitary Abnormalities

This study will determine the safety and activity of a new formulation of thyrotropin-releasing hormone (TRH), a drug used for diagnosing and evaluating patients with certain thyroid gland abnormalities. Normal thyroid gland function depends on proper chemical signaling between the thyroid gland, the hypothalamus (the part of the brain where TRH is made), and the pituitary (another part of the brain). The TRH test helps assess this interaction. Production of the only FDA-approved preparation of TRH was stopped in July 2002. As a result, to have a continuous source of TRH available for NIH clinical and research purposes, the NIH Clinical Center (CC) Pharmacy Department produced a pharmaceutical grade formulation of TRH for patient use. This study will test the CC formulation in healthy volunteers to show that its activity and side effects are similar to those of the previously available commercial test preparation. It will then be studied in CC patients for whom the diagnostic test is recommended. Healthy volunteers between 18 and 65 years of age and all patients requiring TRH evaluation of hypothalamic-pituitary-thyroid gland interaction may be eligible for this study. Patients include those with pituitary reserve, inconsistent thyroid function test, inappropriate TSH secretion, or pre- and post-operative evaluation of pituitary tumors. Normal volunteers will be screened with a medical history, physical examination, and blood tests. Women of child-bearing potential will be given a pregnancy test; pregnant and breast-feeding women may not participate. The TRH test procedure will be the same for healthy volunteers and patients. All participants fast from midnight before the morning of the test. In the morning, a catheter (flexible plastic tube) is inserted into an arm vein for easy injection of the TRH and collection of blood samples. Blood pressure is monitored before and during the test. A blood sample is drawn, and then TRH is given through the catheter over a 1-minute period. Another nine blood samples are collected over a 3-hour period from the time of the TRH injection for measuring levels of various hormones. A total of less than 4 tablespoons of blood is taken for the test.

Sex

All

Minimum age

2 Years

* DIAGNOSTIC STUDY PROTOCOL

Inclusion Criteria:

-All adults and children requiring dynamic testing of the hypothalamic-pituitary axis for the evaluation of pituitary reserve, inconsistent thyroid function test, inappropriate TSH secretion, or pre-and post-operative evaluation of pituitary adenomas (glycoprotein hormone secreting tumors, growth hormone secreting tumors and TSH secreting tumors).

Exclusion Criteria:

* Uncontrolled hypertension;
* Uncontrolled seizure disorder;
* Unstable coronary disease;
* Known allergy to TRH.

RESEARCH PROTOCOLS

-TRH is available for use in other IRB approved research protocols either using the standard diagnostic testing protocol or the modified TRH test.

Exclusion Criteria:

* Untreated hypertension;
* Coronary artery disease;
* History of asthma;
* History of seizures;
* Pregnancy;
* Known allergy to TRH.

• BACKGROUNDJackson IM. Thyrotropin-releasing hormone. N Engl J Med. 1982 Jan 21;306(3):145-55. doi: 10.1056/NEJM198201213060305. No abstract available. PMID 6798440
• BACKGROUNDHaigler ED Jr, Pittman JA Jr, Hershman JM, Baugh CM. Direct evaluation of pituitary thyrotopin reserve utilizing synthetic thyrotopin releasing hormone. J Clin Endocrinol Metab. 1971 Oct;33(4):573-81. doi: 10.1210/jcem-33-4-573. No abstract available. PMID 4999252
• BACKGROUNDFaglia G. The clinical impact of the thyrotropin-releasing hormone test. Thyroid. 1998 Oct;8(10):903-8. doi: 10.1089/thy.1998.8.903. PMID 9827657