Thyrotropin-releasing Hormone Infusion Research Articles

Studies of prolactin and TSH secretion by continuous infusion of small amounts of thyrotropin-releasing hormone (TRH).

ABSTRACT Prolactin and TSH responses to the continuous infusion of 25 to 750 ng/min of TRH were studied in 10 normal subjects and compared to standard TRH tests. Both prolactin and TSH rose shortly after the beginning of a TRH infusion rate of 250 ng/min in women; in men, prolactin rose at an infusion rate of 75 ng/min and TSH rose later during the 250 ng/min infusion rate. These observations indicate that the smallest increases in TRH concentration capable of producing an increase in serum TSH concentration also increase plasma prolactin and support the concept that TRH plays a physiological role in the normal control of prolactin secretion in humans. Both prolactin and TSH responses to TRH were greater in women than in men. TSH continued to rise throughout the higher rates of TRH infusion in spite of increasing serum T3 concentration, and the mean peak TSH rises which occurred in response to 450 min of TRH infusion followed by a 500 μg TRH bolus were far greater than those which occurred during standard...

SERUM TSH RESPONSES TO INTRAVENOUSLY AND ORALLY ADMINISTERED TRH IN MAN AFTER THYROIDECTOMY FOR CARCINOMA OF THE THYROID

SUMMARYFourteen patients whose thyroid glands had been ablated for carcinoma were given intravenous or oral thyrotrophin releasing hormone (TRH) at intervals after stopping replacement thyroid hormone. Despite continuing the TRH infusion, serum thyrotrophin (TSH) rose to reach a peak at 120 min after the start of the infusion, and then fell again towards the pre‐treatment values. Significant responses were seen by 4 days after stopping triodothyronine (T3), but progressively increased with longer intervals off T3. Oral TRH gave a similar pattern of responses. Patients maintained on thyroxine (T4) and changed to T3 4 weeks prior to treatment had smaller TSH responses to TRH than patients maintained continuously on T3. It would seem that: (1) TRH promotes TSH release faster than it promotes synthesis of new hormone under the conditions studied, and (2) that long‐term administration of T3 suppresses TSH secretion from the pituitary in response to TRH less than thyroxine. While it is possible to elevate the serum TSH levels of these patients with thyroid carcinoma into the rane normally seen in primary hypothyroidism by the use of TRH prior to administration of radioiodine without production of clinical symptoms of hypothyroidism, we do not yet know whether such elevation is of benefit in treatment.

Responses to thyrotropin-releasing hormone in patients with renal failure and after infusion in normal men.

Thyrotropin-releasing hormone (TRH) was administered iv to 8 patients with renal failure, 8 normal men, and 5 children. Injection of 1600 μg TRH as a bolus to healthy adults or a smaller dose to children resulted in a normal pattern of TSH release. The prolonged release of TSH which occurred after stat injection of 400 μg TRH to the patients with greatly diminished renal function was similar to that found after a 4-hr infusion of 1600 μg in normal men. In the men receiving the iv infusion, TSH levels began to diminish after 2 hr, despite the continued infusion of TRH for an additional 2 hr. An unexpected increase of hGH was also found in 7 of 8 patients with renal failure after injection of TRH.