The Spectrum of Pituitary Growth Hormone Responses to Pharmacological Stimuli in Acromegaly*

Hanew, Kunihiko; Kokubun, Masaru; Sasaki, Akira; Mouri, Toraichi; Yoshinaga, Kaoru

doi:10.1210/jcem-51-2-292

Cited by 82 publications

(39 citation statements)

References 31 publications

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“…Tais casos são relativamente raros, representando cerca de 3,7% dos casos na maioria dos estudos (7,8). Assim sendo, uma única dosagem do GH basal não constitui um marcador confiável para o diagnósti-co ou exclusão da acromegalia; testes dinâmicos que avaliam a regulação do GH devem sempre ser realizados para confirmação diagnóstica (3,(9)(10)(11).…”

Section: Discussionunclassified

Acromegalia com níveis séricos basais do hormônio do crescimento dentro dos limites da normalidade

Costa

Silva

Violante

et al. 2000

Arq Bras Endocrinol Metab

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A acromegalia é uma síndrome causada pela hipersecreção do hormônio de crescimento (GH). No entanto, alguns pacientes podem apresentar níveis séricos limítrofes, ou mesmo dentro da normalidade, dificultando o diagnóstico. Relatamos um caso de acromegalia cuja investigação diagnóstica inicial evidenciou níveis séricos basais de GH dentro dos limites da normalidade e tomografia computadorizada (TC) de sela túrcica normal. A confirmação da doença só foi estabelecida através de testes dinâmicos que avaliam a regulação do GH (dosagem de GH durante o teste oral de tolerância à glicose e após TRH) e confirmada pela ressonância nuclear magnética (RNM) de sela túrcica que evidenciou imagem sugestiva de microadenoma. A paciente foi submetida à cirurgia hipofisária pela via de acesso oronaso esfenoidal e a área tumoral encaminhada para estudo imunohistoquímico, corroborando o diagnóstico de acromegalia. A avaliação dinâmica no pós operatório evidenciou regulação normal do GH. Discutimos os critérios diagnósticos da acromegalia, com ênfase na importância de se prosseguir com a investigação sempre que houver uma forte suspeita clínica, mesmo que os exames iniciais se apresentem dentro dos limites da normalidade. ABSTRACTAcromegaly is a syndrome caused by growth hormone (GH) hypersecretion. However, some patients can present normal or near normal levels of GH, difficulting diagnosis. We report an acromegalic patient with normal levels of GH and negative imaging at initial investigation. Acromegaly was confirmed by dynamic tests (glucose tolerance test and GH-TRH), and RMI was suggestive of a microadenoma. The patient was submitted to a transesphenoidal pituitary surgery and imunohistochemistry study, corroborating the diagnosis of acromegaly. Dynamic tests performed after surgery evidenced normal GH regulation. Considerations on the diagnosis of acromegaly were also done, emphasizing the importance of continuing the investigation whenever clinical suspicion persists, even though the initial tests are within the normal range.

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Section: Discussionunclassified

Acromegalia com níveis séricos basais do hormônio do crescimento dentro dos limites da normalidade

Costa

Silva

Violante

et al. 2000

Arq Bras Endocrinol Metab

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“…GIH (somatostatin, Protein Research Foundation, Osaka ; 500 ,u g), arginine (l0% L-arginine-HC1, Morishita, Osaka ; 0.5 g/kg BW), TRH (Tanabe Pharmaceutical Co., Tokyo ; 500 jig), LH-RH (Daiichi Pharmaceutical Co., 100 jig), and L-dopa (Sankyo Pharmaceutical Co., 500 mg) were used in the present study. Blood sampling and administration of these agents were accomplished as described previously (Hanew et al 1977(Hanew et al , 1980. Plasma GH was measured in duplicate according to the methods described previously (Hannew et al 1980).…”

Section: Methodsmentioning

confidence: 99%

“…It is well known that acromegalic patients often respond to exogenous stimuli with an increase or decrease in GH release (Hanew et al 1980). As TRH, LH-RH, somatostatin and dopamine modulate the GH secretion from acromegalic pituitary either in vivo or in vitro, the presence of respective receptors has been postulated (Irie and Liuzzi et al (1974) have already reported the mutual relationships between the responses to TRH and to dopaminergic agents in these patients.…”

mentioning

confidence: 99%

Comparative study on the responses of plasma GH to synthetic GH-releasing factor and other stimulatory and inhibitory agents in patients with acromegaly.

Hanew

Sato

Sasaki

et al. 1985

Tohoku J. Exp. Med.

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Ten patients with active acromegaly received synthetic human pancreatic GH releasing factor (hpGHRF-44), and the GH responses to GHRF were compared with the basal GH levels and with the GH responses to arginine, TRH, LH-RH, somatostatin, and L-dopa. There were no significant relationships between the plasma GH responses to GHRF and the results of the stimulatory and inhibitory tests mentioned above, except that the responses to GHRF showed weak positive or negative correlations with the responses to LH-RH (r= +0.56) or with the basal GH levels (r--0.57). These results indicate that acromegalic somatotrophs would have GHRF receptors as well as several other receptors to hypothalamic hormones and to dopamine, and that there might be no distinct relationship between the somatotroph sensitivities to GHRF and to other stimulatory or inhibitory stimuli. Further studies are required regarding the weak correlations between the response to GHRF and that to LH-RH or basal GH value.

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“…Thyrotropinreleasing hormone (TRH) stimulation test, oral glucose tolerance test (OGTT) and insulin-like growth factor (IGF)-I levels are helpful for the diagnosis of acromegaly. TRH-induced GH release would be caused by the abnormal induction or sensitization of TRH receptors on pituitary somatotroph adenoma cells (Harvey 1990), and plasma GH levels are elevated in response to TRH in 70-80% of acromegaly (Irie and Tsushima 1972;Hanew et al 1980). The plasma GH levels are examined by an OGTT, and acromegaly is diagnosed as a failure of decrease in plasma GH level to the normal level after an OGTT (Stewart et al 1989).…”

confidence: 99%

“…The administration of TRH stimulates GH levels in acromegalic patients (Irie and Tsushima 1972;Hanew et al 1980). The effects of TRH on GH levels were, therefore, examined in these patients.…”

Section: Gh Response To Trhmentioning

confidence: 99%

Usefulness of the Thyrotropin-Releasing Hormone Test in Pre-Clinical Acromegaly

Kageyama

Moriyama

Sakihara

et al. 2005

Tohoku J. Exp. Med.

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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. growth hormone; acromegaly; insulinlike growth factor-I; pituitary tumor

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The Spectrum of Pituitary Growth Hormone Responses to Pharmacological Stimuli in Acromegaly*

Cited by 82 publications

References 31 publications

Acromegalia com níveis séricos basais do hormônio do crescimento dentro dos limites da normalidade

Acromegalia com níveis séricos basais do hormônio do crescimento dentro dos limites da normalidade

Comparative study on the responses of plasma GH to synthetic GH-releasing factor and other stimulatory and inhibitory agents in patients with acromegaly.

Usefulness of the Thyrotropin-Releasing Hormone Test in Pre-Clinical Acromegaly

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