Poster Presentation ESA-SRB-ANZOS 2025 in conjunction with ENSA

Bone health in phenylketonuria (127321)

Jodi Hart 1 , Young How Lam 1 , Catherine Manolikos 1 , Yi Xian Chan 1 2 , Samantha Hodge 1 , Suchitra Raj 1 , Nely Shrestha-Khatri 1 , Damon Bell 1 , Kharis Burns 1 2
  1. Endocrinology and Diabetes, Royal Perth Hospital, Perth, Western Australia, Australia
  2. Medical School, University of Western Australia, Nedlands, Western Australia, Australia

Aims: Phenylketonuria (PKU) is the most common inborn error of amino acid metabolism. With improved life expectancy due to early diagnosis and dietary management, attention has turned to long-term outcomes, including bone health. Adults with PKU may be at risk of compromised bone health, though contributing factors and utility of routine screening remain uncertain.1-3

Methods: We retrospectively reviewed 59 adults with PKU attending Western Australia’s Inborn Errors of Metabolism clinic. Data included demographics, body mass index (BMI), adherence to dietary protein restriction, plasma phenylalanine (Phe) levels, bone turnover markers and bone mineral density (BMD) via dual-energy X-ray absorptiometry.

Results: The cohort (57.6% female) had a mean age of 40.2 ± 16.5 years (range: 18-78 years) and BMI of 27.7 ± 7.4 kg/m². Of these, 40.7% were always adherent to diet, 50.8% were partially adherent, and 8.5% were non-adherent. Mean 12-month plasma Phe level was 851.7 ± 371.8 µmol/L. Among 36 patients with BMD data, 27.7% had Z-scores >-2 to <–1 and 11.1% had Z-scores ≤–2. Among patients over 50 years of age (n=12), osteopaenia (T-score >-2.5 to <–1) and osteoporosis (T-score ≤–2.5) were present in 50% and 17%, respectively. Most were vitamin D replete and normocalcaemic (mean 25-OH vitamin D: 91.8 ± 36 nmol/L; adjusted calcium: 2.28 ± 0.08 mmol/L).

There was no association between BMD Z-scores and BMI, Phe level, or dietary adherence. No correlation was observed between Phe levels and bone turnover markers (serum CTX or ALP).

Conclusion: Consistent with previous studies, a substantial proportion of adults with PKU have low BMD. However, most BMD values remain within the expected range for age. These findings support the need for regular bone health assessment in this population. Further research assessing risk factors for low BMD and in examining future fracture risk is required to identify patients with PKU requiring earlier screening.
GEKO:52996

  1. Rocha JC, Hermida Á, Jones CJ, et al. Meta-analysis of bone mineral density in adults with phenylketonuria. Orphanet J Rare Dis. 2024;19(1):338. doi:10.1186/s13023-024-03223-9.
  2. de Castro MJ, de Lamas C, Sánchez-Pintos P, et al. Bone status in patients with phenylketonuria: a systematic review. Nutrients. 2020 Jul 20;12(7):2154. doi:10.3390/nu12072154.
  3. Demirdas S, Coakley KE, Bisschop PH, et al. Bone health in phenylketonuria: a systematic review and meta-analysis. Orphanet J Rare Dis. 2015;10:17. doi:10.1186/s13023-015-0232-y.