Acromegaly: Balance, Falls and Fracture Risk

Patients with an established diagnosis of acromegaly will be recruited from March 2023 to March 2025. Patients will be informed of the study during scheduled visits to the pituitary endocrinology outpatient clinic at Aalborg University Hospital by one of two specialists in pituitary endocrinology. Patients will be given information regarding the study, and if interested, they will be provided with a form to fill out with their contact information, so they can be contacted by the investigators or other staff affiliated with the study. Should the patient agree to be contacted via telephone or e-mail, they will be given an instruction regarding their rights as a participant in a scientific study ("Dine rettigheder som forsøgsperson i et sundhedsvidenskabeligt forskningsprojekt") as well as written material specifically pertaining to the study ("Deltagerinformation"). Should the subject be deemed fit for the study, based on the in- and exclusion criteria, contact will be made via phone or e-mail and they will receive further information regarding the study, and offered a personal meeting with one of the investigators, where details of the study procedures will be outlined. The meeting will take place in a dedicated, undisturbed office at the disposition of the Department of Endocrinology, in order to ensure due privacy during the meeting. In advance, the subject will be informed of the opportunity to bring a relative or other representative to the meeting. At the meeting, the participant and any representative will be informed of the 24-hour deliberation period before providing informed consent. No study procedures will be performed until the informed consent form has been signed by both the participant and the investigator.

As mentioned above, healthy controls will be recruited via the aforementioned database, social media and websites such as www.forsoegsperson.dk. Potential participants who contact the principal investigator through these channels will be provided with written material pertaining to the study ("Deltagerinformation") and a description of their legal rights as a participant ("Dine rettigheder som forsøgsperson i et sundhedsvidenskabeligt forskningsprojekt"). Should the potential participant meet the in- and exclusion criteria, they will be invited to a personal meeting, where details of the study are explained, having been informed of the opportunity to bring a representative or relative to the meeting in advance. Should they wish to participate, a 24-hour deliberation period will be given prior to obtaining written informed consent.

After providing informed consent, the participants will undergo a series of study procedures. Bone quality will be assessed by way of High-Resolution peripheral Quantitative Computed Tomography (HR-pQCT) images of the distal radius and tibia. Bone material strength index (BMSi) is assessed using an OsteoProbe. In addition to this, postural control will be assessed using a balance board to obtain a surrogate measure of fall risk. Body composition, bone mineral density and vertebral fracture assessment (VFA) will be analyzed via Dual X-ray Absorptiometry (DXA) scans and peripheral muscle strength will be assessed via hand grip strength and knee extension torque measurements, and visual acuity tested with standard methods. Data will be analyzed using relevant statistical analyses and presented as a cross-sectional study.

HIGH RESOLUTION PERIPHERAL QUANTITATIVE COMPUTED TOMOGRAPHY (HR-PQCT) HR-pQCT is a 3-dimensional imaging modality that can be applied to bone and joints in vivo, in order to non-invasively assess the quantity and quality of trabecular and cortical bone compartments separately. HR-pQCT will be applied to peripheral skeletal sites, namely the distal radius and tibia, where image slices equivalent to 9 mm of bone will be acquired. From this, parameters such as volumetric bone mineral density (vBMD), cortical density, cortical porosity, trabecular density, trabecular thickness, trabecular spacing and others will be calculated using specialized software. In the same scanning session, images of the wrist and ankle joints will be produced and analyzed for features of arthrosis, such as erosions, osteophytosis and others.

The scanner's gantry is relatively narrow and shallow (rear physical stop) only allowing the distal peripheral skeleton to be accommodated. The limb being scanned is immobilized in a carbon fiber shell. A scout view, essentially a two-dimensional x-ray scan, is obtained so that the operator can identify a precise region for the three-dimensional measurement. Because HR-pQCT uses a polychromatic X-ray source it is subject to beam hardening as well as scatter artefacts, which can significantly impact geometric and densitometric measures. Once the images have been acquired, a default patient evaluation protocol is used to analyze the scans over the entire 9 mm three-dimensional region to assess a wide range of standard and optional structural and density parameters.