|Year : 2013 | Volume
| Issue : 1 | Page : 60-63
A case of pituitary macro-adenoma with acromegaly and visual field defects
Kakollu Satyanarayana Rao, Kota Ramalakshmi, Dana Srinivasa Rao, Kurada Venkata Seshaiah
Department of Medicine, Government Siddhartha Medical College, Vijayawada, Andhra Pradesh, India
|Date of Web Publication||13-Mar-2013|
Kurada Venkata Seshaiah
Department of Medicine, Government Siddhartha Medical College, Vijayawada - 520 008, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
A 45-year-old female visited our medical out-patient department with a history of gradual increase in the thickness of her skin and prominence of lower jaw and forehead in the past 10 years. Hormonal assay revealed unsuppressed growth hormone levels (7.86 ng/ml) with oral glucose load at 1 hour. Magnetic resonance imaging (MRI) of brain showed pituitary macroadenoma. Perimetric examination revealed visual field defects. Clinical, hormonal, imaging, and perimetric studies together confirmed the diagnosis of pituitary macroadenoma with acromegaly and pressure effects.
Keywords: Acromegaly, growth hormone, IGF-1, macroadenoma, perimetry
|How to cite this article:|
Rao KS, Ramalakshmi K, Rao DS, Seshaiah KV. A case of pituitary macro-adenoma with acromegaly and visual field defects. J NTR Univ Health Sci 2013;2:60-3
|How to cite this URL:|
Rao KS, Ramalakshmi K, Rao DS, Seshaiah KV. A case of pituitary macro-adenoma with acromegaly and visual field defects. J NTR Univ Health Sci [serial online] 2013 [cited 2020 Apr 7];2:60-3. Available from: http://www.jdrntruhs.org/text.asp?2013/2/1/60/108518
| Introduction|| |
Incidence of acromegaly is 3-4 cases per million population, and its prevalence is estimated to range from 38 to 69 cases per million.  More than 99% of patients with acromegaly harbor a growth hormone (GH ) secreting pituitary adenoma. Average duration from symptoms onset to diagnosis is often 4-10 years. Pituitary tumors account for about 15% of primary intracranial neoplasms. Given the critical location of the gland, expanding tumors cause compressive symptoms. When tumors arise in pituitary somatotroph cells, aberrant secretion of GH leads to the distinctive features of acromegaly.
| Case Report|| |
A 45-year-old female presented with chief complaints of gradual increase in the thickness of her skin and prominence of lower jaw and forehead in the past 10 years. She also complained of hoarseness of voice, discomfort in swallowing, and snoring during sleep for past 1 year. She reported no history of diabetes or hypertension before admission. She was a multipara with normal menstrual and antenatal history. Family history was negative for similar complaints [Figure 1]a and b.
On examination, she had thick coarse skin; enlargement of nose, lips, fingers and hands; prominent heel pads; and macroglossia. Vitals were normal except her blood pressure (BP; 150/100 mmHg). Systemic examination including fundus was unremarkable. Confrontation method could not reveal any visual field abnormalities.
In biochemical evaluation, she was found to be diabetic with fasting and post-prandial blood glucose levels of 160 mg/dl and 236 mg/dl, respectively. Lipid profile showed serum cholesterol at 223 mg/dl, low-density lipoprotein (LDL) of 146 mg/dl, and high-density lipoprotein (HDL) of 38 mg/dl. Elevated serum insulin-like growth factor-1 (IGF-1) level was 869 ng/ml with unsuppressed serum GH levels (nadir levels of 7.86 ng/ml) during glucose suppression test, confirming the diagnosis of acromegaly. Other anterior pituitary hormonal values are unremarkable [Table 1]. X-ray skull revealed increased size of sella turcica. MRI brain revealed a pituitary adenoma of size 16 × 12 mm [Figure 2]. X-rays of both hands showed increased soft tissue densities, inter-phalangial joint spaces, and cortical densities of metacarpals and phalanges. X-rays lateral view of both feet showed increased heel-pad thickness of 35 mm (normal is 22 mm) [Figure 3]a and b. Perimetric study revealed binasal hemianopia with involvement of left upper temporal field [Figure 4]a and b. Computed tomography (CT) scan of chest and abdomen ruled out ectopic tumors.
|Figure 4: (a, b) Perimetry showing visual fi eld defects (binasal hemianopia with upper left temporal defect)|
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| Discussion|| |
Acromegaly, well described in antiquity, was recognized as a distinct clinical syndrome by Marie in 1886. The pituitary source of the disorder was confirmed in 1909 by Cushing, who postulated the excessive secretion of GH by a hyperfunctioning pituitary gland. 
Physiology of somatotrophs
The release of GH occurs in a pulsatile fashion. There are approximately 10 intermittent pulses of GH per 24 hours.  Secretion of GH is stimulated by hypothalamic GHRH and fasting, while suppressed by somatostatin, circulating GH and IGF-1, glucocorticoids as well as aging. The main biological effect of GH is promotion of linear growth in post-natal life, until completion of puberty. Excess production of GH prior to the closure of epiphyses leads to gigantism, while, in adults, it causes acromegaly. 
Pathogenensis of somatotroph adenoma
Both pituitary and hypothalamic factors influence pituitary tumor pathogenesis. These tumors are usually benign. Densely granulated adenomas grow slowly and are usually seen in older patients. Sparsely granulated adenomas are rapidly growing and are seen in younger individuals. About 25% of GH adenomas co-secrete prolactin. Tumors may be monomorphous or dimorphous and secrete single or multiple hormones.  In 98% of cases of acromegaly, the source of excess GH is pituitary somatotroph adenoma. Rarely, excess GH may be due to ectopic tumors, secreting either GHRH or GH. Familial acromegaly syndromes are rare.
The elevated GH and IGF-1 in acromegaly lead to a wide range of cardiovascular, respiratory, endocrine, and metabolic morbidities.  The clinical manifestations range from subtle signs of acral overgrowth, soft tissue swelling, arthralgias, jaw prognathism, fasting hyperglycemia, and hyperhidrosis to florid osteoarthritis, frontal bone bossing, diabetes mellitus, hypertension, and respiratory and cardiac failure.  Enlarging pituitary macroadenoma (>10 mm) may cause visual field defects and signs of raised intracranial tension. Although bitemporal hemianopia is the most common defect, any type of visual field defect can occur depending on the direction of growth and involvement of fibers as in our patient, who had binasal hemianopia with involvement of upper temporal field in left eye. Benign colonic polyps have been reported in 45% of patients. Colonoscopy is warranted every 3-5 years. 
The diagnosis of acromegaly can be made on the basis of characteristic clinical appearance. Serial photographs provide a good evidence for clinical diagnosis. Failure of GH suppression to <1 ng/ml is considered diagnostic. MRI with contrast is the gold standard for diagnosis. 
Aim of treatment is to normalize GH and IGF-1 levels, to remove tumor mass effect, and to preserve normal pituitary function.  Treatment options include surgery, drugs, and radiotherapy. 
Choice of therapy
Trans-sphenoidal surgery is recommended for most patients. But remission rates are 80% for microadenomas and only <50% for macroadenomas. Radiotherapy is reserved for tumors that have recurred or persisted after surgery in patients with resistance to or intolerance of medical treatment. Medical therapy includes somatostatin analogues (Octreotide LAR, Lanreotide, Pasreotide), dopamine agonists (Bromocriptine, Cabergoline), and GH receptor antagonists (Pegvisomant). Because of their cost, in Indian scenario, these drugs are used while waiting for the radiotherapy to be effective or after insufficient surgical removal of adenoma.  In our case, the patient and her attendants denied surgery in spite of repeated motivations. She has been under follow-up, twice monthly, for her hypertension and diabetes.
Criteria of cure 
GH levels <2.5 ng/ml, young age, shorter duration of disease, and absence of hypertension are predictors of longer survival.  Untreated acromegaly is associated with a significant morbidity and a reduced life expectancy.  Cardiovascular disease is the leading cause of death. 
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]