Clinical features, Presentation and Investigation
Dr Rajesh Rajendran
ST3 Endocrinology / Diabetes
Recognise him ?
Now... Richard Keil
Clinical Features
• Incidence is ~ 4 cases per 1 million per
year
• Prevalence is about 40-60 per million
• Develop insidiously over decades
• Delay of 7 to 10 years in diagnosis after
the estimated onset of symptoms
• Most cases are diagnosed at 40-60 years
Clinical Features
> 95% of patients harbour a GH secreting
pituitary adenoma
Extra pituitary source 2 mcg/L: 85 percent of patients with acromegaly
• Gold standard for determining control of GH secretion after
surgical treatment
• Not useful in assessing biochemical control in patients receiving
medical therapy with somatostatin analogs
• A single two-hour serum GH measurement is usually adequate
Oral glucose tolerance test
• Newer, highly sensitive assay:
immunoradiometric or
immunochemiluminescent GH assay
• Normal: Serum GH falls to ≤ 0.3 mcg/L
• Acromegaly: Serum GH > 0.3 mcg/L
• Better discrimination between those with and
without acromegaly
Other dynamic tests
TRH: (500 mcg iv)
• ↑ serum GH by 50% or more in one-half of patients
with acromegaly
• peak values occurring at 20 to 30 minutes
• serum GH does not rise in normal subjects
L-dopa: (500 mg orally)
• ↓ serum GH by 50% or more in about one-half of
patients with acromegaly
• while it raises the GH in normal subjects
GH dependant molecules
Serum IGFBP-3:
• Elevated in patients with acromegaly
• Considerable overlap of these values with those in normal
persons
• Limits the utility of this measurement
Serum IGF-1:
• Invariably elevated in acromegaly
• Exception: severe intercurrent illness
• The results must be interpreted according to the patient's
age
• Values from one laboratory may not be comparable to
those from another laboratory
• Measured in mcg/L
Others:
Random GH:
• not useful in diagnosis but if < 1mU/L then
the diagnosis is excluded
Pituitary function testing:
• Insulin tolerance test
• Prolactin
GHRH:
• If pituitary tumour not identified
MRI Pituitary
• Somatotroph adenoma of the pituitary is by far the
most common cause
• Tumours as small as 2 mm in diameter can be
detected
• Dimensions & anatomic extent accurately identified
• Does not distinguish between functioning and non
functioning tumours
• This is an important concern because approximately
10 to 20 percent of normal subjects have MRI or
autopsy evidence of a pituitary microadenoma
Other causes for elevated GH
Pain Heart failure
Pregnancy Diabetes Mellitus
Puberty Malnutrition
Adolescence if tall Prolonged fast
Stress Severe illness
Chronic Renal Failure Heroin addiction
Chronic Liver Failure
Investigation algorithm
Thank you