ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2006) 12 P18

Acromegaly with normal pituitary

PN Murthy & PH Davies


Sandwell General Hospital, West Bromwich, West Midlands, United Kingdom.


A 51 yr old woman presented to ENT surgeons with nasal polyps. Since examination revealed a multi-nodular goitre, large hands and prognathism, acromegaly was suspected. MRI of the pituitary arranged, was normal. Two years later, nasal polyps returned. CT on this occasion showed evidence of polyps with sinusitis but again a normal pituitary fossa. She was referred to a rheumatologist for carpal tunnel symptoms, the features of acromegaly were rediscovered and she was referred to our endocrine clinic.

Endocrine testing confirmed growth hormone [GH] excess at 13.5 m IU/l with IGF-1 of 188.8 nmol/l. GH values across a 2 hour OGTT were showing a typical paradoxical rise in GH, confirming the diagnoses of acromegaly.

   
TimeGlucose mMol/lGH m IU/l
05.713.5
308.68.0
609.410.8
906.711.0
1204.014.4

CT of chest, abdomen and pelvis was normal with no evidence of neuro-endocrine tumour. Urinary 5-HIAA and Chromogranin A were normal. Further tests are awaited including Octreotide-Scan and GHRH [Growth Hormone Releasing Hormone] levels [Barts]. Possible diagnoses include a GHRH-oma in the chest or abdomen below the sensitivity of CT scan, or her nodular thyroid is another potential site.

95% of cases of acromegaly are caused by pituitary somatotroph adenomas. GHRH-induced acromegaly is rare and clinically indistinguishable from acromegaly caused by pituitary adenomas. GHRH-induced acromegaly is typically caused by carcinoid tumors typically of Pancreas or lung, but may arise in from endocrine cells from other tissues. Imaging can usually reveal GHRH secreting carcinoids allowing primary surgical treatment. GHRH secretion can also be managed medically with somatostatin analogs. Our patient has had impressive symptomatic relief with Sandostatin LAR 20 mg/month

Eutopic hypothalamic GHRH secretion in to the hypophyseal portal system does not enter the systemic circulation. Elevated circulating GHRH levels, a normal sized pituitary gland, or clinical and biochemical features of other tumours known to be associated with extra pituitary acromegaly are all indications for extra pituitary imaging.

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