Acromegaly Associated With Lacrimal Gland Volume, IGF-1, Serum Growth Hormone Increases

Lacrimal gland volume may be larger in patients with acromegaly, which correlates with an increase in levels of insulin-like growth factor-1 (IGF-1) and serum growth hormone (GH), according to research results published in Growth Hormone & IGF Research. 

In a prospective, multidisciplinary study of patients with controlled or uncontrolled acromegaly, researchers sought to both investigate lacrimal gland volume changes spanning a 6-month period and evaluate the effect of these changes on tear film function. Patients with acromegaly were compared with a control group of patients with nonfunctioning pituitary adenoma. 

The primary study outcome was lacrimal gland volume at baseline, month 3, and month 6, with secondary study outcomes of serum GH and IGF-1 levels, Schirmer test results, tear breakup time (TBUT), and ocular surface disease index (OSDI) score. Lacrimal gland volume was calculated by T1-weighted FLAIR sequence orbital MRI; each patient underwent a Schirmer test without anesthesia followed by TBUT measurement after 30 minutes. 

The total study cohort included 38 eyes from 38 patients with uncontrolled acromegaly, 48 eyes from 48 patients with controlled acromegaly, and 44 eyes from 44 patients in the control group. Mean age for acromegaly patients (n=86) was 46.4±12.8 years and 47.5±11.0 for controls (66.3% and 68.2% women, respectively). 

Mean disease duration for uncontrolled acromegaly was 7.0±6.3 years; 5.8% of patients had hypothyroidism, 1.2% had hypoparathyroidism, and 2.3% had hypopituitarism. 

In the acromegaly group, mean lacrimal gland volume was 116.0±33.2 mm³ and 119±36.4 mm³ at baseline and month 3, respectively. This measurement was higher than that of the control group: 65.2±22.3 mm³ and 63.2±22.3 mm³. In the control group, lacrimal gland volume did not significantly change in 3 months; in the acromegaly group, mean lacrimal gland volume did not show any significant changes at month 6. 

No significant changes for Schrimer, TBUT, and OSDI scores were seen in the acromegaly or control group for 3 consecutive visits. Both IGF-1 and GH levels demonstrated a strong positive correlation with lacrimal gland volume, although no correlation was noted in the control group. Also in this group, IGF-1 demonstrated a negative correlation with Schirmer and TBUT values. 

In an additional analysis, the acromegaly group was divided into controlled and uncontrolled acromegaly patients (mean ages, 45.2±13.3 and 47.4±12.4 years, respectively; 72.9% and 57.9% women). 

Lacrimal gland volume in both acromegaly groups was significantly higher vs participants in the control group, with no significant difference between controlled and uncontrolled patients. At month 3, mean lacrimal gland volume of those with uncontrolled acromegaly was higher than those with controlled acromegaly and the control group (129.4±36.5 mm³ vs 117.3±34.7 mm³ and 63.2±22.3 mm³); at 6 months, mean lacrimal gland volume remained elevated in uncontrolled vs controlled acromegaly. 

For patients with controlled acromegaly, lacrimal gland volume did not show any significant changes across the 3 visits, and the between-group analysis of these 3 visits did not demonstrate any significant differences. 

No significant differences were seen in terms of tear film functions among the 3 groups. IGF-1 levels were higher in uncontrolled vs controlled acromegaly and in controlled acromegaly vs the control group; this difference persisted throughout the month 3 visit. GH levels were also higher in people with acromegaly compared with controls. 

Study limitations include difficulties in determining the lacrimal gland volume increase prior to diagnosis, a low number of patients on hormone replacement therapy, and the potential effect of somatostatin analogs on tear film function. 

“We observed a higher [lacrimal gland volume] in acromegaly patients compared to the control group,” the research shows. “The increased [lacrimal gland volume] did not seem to cause any change in the tear film functions. Further histopathological studies are needed to better understand the mechanism of action of IGF-1 on the functions of the lacrimal gland.” 

Reference

Mergen B, Arici C, Kizilkilic O, Tanriover N, Kadioglu P. Lacrimal gland enlargement and tear film changes in acromegaly patients: A controlled study. Growth Horm IGF Res. Published online May 11, 2021. doi:10.1016/j.ghir.2021.101397

This article originally appeared on Ophthalmology Advisor