Usefulness of the thyrotropin-releasing hormone test in pre-clinical acromegaly.
Acromegaly is caused primarily by pituitary growth hormone (GH)-secreting tumors. It is usually recognized because of characteristic manifestations, and diagnosed clinically. However, there exists a mild stage of acromegaly, which poses a diagnostic problem due to the absence of typical clinical manifestations. Here we present four patients with pre-clinical acromegaly, who showed minimal acromegaloid features with elevated levels of insulin-like growth factor-I. Basal GH levels were within normal levels in 3 of 4 cases, while insulin-like growth factor-I levels were elevated above normal in all cases. Plasma GH levels were elevated in response to thyrotropin-releasing hormone (TRH) in all cases, indicating a diagnostic value of the TRH stimulation test. In contrast, an oral glucose tolerance test was not useful for the diagnosis, because of the low GH levels (less than 1 ng/ml) and/or secondary to diabetes mellitus. In response to a dopamine agonist, GH levels were increased in the two cases, whereas GH levels were decreased or remained unchanged in the other two cases. We therefore suggest that the TRH stimulation test would be helpful to examine the presence of pre-clinical acromegaly. Diagnosis of the early stages of acromegaly is important to prevent progression to overt acromegaly.
Department of Endocrinology, Metabolism and Infectious Diseases, Hirosaki University School of Medicine, 5 Zaifu-cho, Hirosaki, Japan. kkageyama@hkg.odn.ne.jp
Kazunori
K
Kageyama
Takako
T
Moriyama
Satoru
S
Sakihara
Shinobu
S
Takayasu
Takeshi
T
Nigawara
Toshihiro
T
Suda
D000172:Acromegaly / Q000097:blood / Q000175:diagnosis* / Q000473:pathology; D000368:Aged; D001971:Bromocriptine / Q000008:administration & dosage / Q000378:metabolism; D018491:Dopamine Agonists / Q000008:administration & dosage / Q000378:metabolism; D005260:Female; D005951:Glucose Tolerance Test; D019382:Human Growth Hormone / Q000097:blood; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D013973:Thyrotropin-Releasing Hormone / Q000008:administration & dosage
D018491:Dopamine Agonists; D019382:Human Growth Hormone; D001971:Bromocriptine; D013973:Thyrotropin-Releasing Hormone; D007334:Insulin-Like Growth Factor I