When IGF-1 Misleads: Discordant Biochemical Findings in Acromegaly
https://doi.org/10.15605/jafes.041.S1
- Author:
Ashwini Chandrasekaran
1
;
Subashini Rajoo
1
;
Gayathri Devi Krishnan
1
;
Shazatul Reza
1
;
Sharifah Noor Adrilla
1
;
Xe Hui Lee
2
Author Information
1. Hospital Kuala Lumpur
2. Hospital Pulau Pinang
- Publication Type:Journal Article
- MeSH:
Acromegaly;
Insulin-Like Growth Factor I
- From:
Journal of the ASEAN Federation of Endocrine Societies
2026;41(S1):90-
- CountryPhilippines
- Language:English
-
Abstract:
Introduction:Acromegaly is an endocrine disorder caused by excess
growth hormone (GH), causing somatic overgrowth,
multiple comorbidities, and premature mortality. It is
confirmed biochemically by an elevated GH level, which
is not suppressed post oral glucose tolerance test (OGTT).
The serum level of insulin-like growth factor-1 (IGF-1) is
recommended for diagnosis, monitoring, and screening,
and a normal level effectively excludes the disease. We
report a patient with acromegaly who presented with
normal IGF-1.
Case:A 21-year-old female, with no known medical illness,
presented with a persistent, progressive headache and
amenorrhea for the past 6 months. She also noticed
a change in facial appearance and an increase in the
size of her hands and feet. Blood parameters revealed
raised GH level of >50 ng/mL, normal IGF-1 30.3 nmol/L
(12.17–44.80), mildly raised prolactin 692 mIU/L, low am
cortisol 62 nmol/L (166–507), thyroid-stimulating hormone
of 0.63 mIU/L (0.27–4.20), free thyroxine 4 11 pmol/L
(12–22), low follicle-stimulating hormone 0.90 IU/L,
luteinizing hormone <0.30 IU/L, estradiol <18.4 pmol/L,
and fasting blood sugar of 17.7 mmol/L with hemoglobin
A1c 9%. In view of normal IGF-1 with a high index of
suspicion for acromegaly, she underwent OGTT which
showed unsuppressed GH. Magnetic resonance imaging
pituitary showed sellar mass 2.4 × 2.9 × 2.1 cm with
suprasellar extension as well as extension into the right
cavernous sinus, suggestive of pituitary macroadenoma.
She was diagnosed with acromegaly with secondary
adrenal insufficiency and central hypothyroidism with
hypogonadotropic hypogonadism, complicated with
poorly controlled diabetes. She was started on thyroxine
and hydrocortisone replacement and required basal bolus
insulin of 1.3 u/kg/day. Repeated IGF-1 showed a raised value, 85.4 nmol/L, after optimization of diabetes. She
underwent endoscopic transsphenoidal surgery with
normalization of blood sugar post-surgery. Blood pressure
was normal throughout.
Conclusion:False negative or normal IGF-1 levels may result in patients
with hepatic or renal failure, hypothyroidism, malnutrition, use of oral estrogen, severe infection, and poorly
controlled diabetes mellitus. Hence, a low or normal IGF1 does not exclude acromegaly in patients with a high
index of suspicion and warrants further investigation.
- Full text:2026080414531565427EP_A128.pdf
