Evaluations of exercise intolerance with cardiopulmonary exercise tests in a 24-year-old young male with obesity with tetrahydrobiopterin deficiency: A case report

Authors

Chun-Yu Chen, Department of Physical Medicine and Rehabilitation, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
Shin-Tsu Chang, Department of Physical Medicine and Rehabilitation, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
Ko-Long Lin, Department of Physical Medicine and Rehabilitation, Kaohsiung Medical University Chung-Ho Memorial Hospital, Kaohsiung, Taiwan
Mu-Hsun Wu, Department of Physical Medicine and Rehabilitation, Kaohsiung Medical University Chung-Ho Memorial Hospital, Kaohsiung, TaiwanFollow

Abstract

Phenylketonuria (PKU) is a rare amino acid metabolism genetic disorder. Tetrahydrobiopterin (BH4) metabolism defects cause variant PKU. BH4 coenzyme deficiency disables phenylalanine metabolism into tyrosine, causing brain damage and intellectual impairment. Patients follow a low-phenylalanine diet for life, increasing the risk of obesity, hypertension, and metabolic syndrome. A 24-year-old male patient with BH4 deficiency underwent a pulmonary function test and cardiopulmonary exercise test (CPET). Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were within normal values, with an 80.68% ratio. The 20-watt bicycle exercise test indicated moderate functional impairment (27.3 ml/kg/min of peak oxygen intake). The test achieved 81% and 70% of the target and reserve heart rates, respectively. The patient’s body mass index was 29.9 kg/m2, causing a high resting metabolic rate and oxygen uptake. The need for oxygen uptake is more prominent during high-intensity exercise, thus his functional impairment was caused by obesity. CPET evaluates cardiorespiratory fitness in patients with PKU, providing appropriate aerobic and resistance training to improve prognosis with a weight control program.

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Recommended Citation

Chen, Chun-Yu; Chang, Shin-Tsu; Lin, Ko-Long; and Wu, Mu-Hsun (2024) "Evaluations of exercise intolerance with cardiopulmonary exercise tests in a 24-year-old young male with obesity with tetrahydrobiopterin deficiency: A case report," Rehabilitation Practice and Science: Vol. 2024: Iss. 1, Article 6.
DOI: https://doi.org/10.6315/3005-3846.2235
Available at: https://rps.researchcommons.org/journal/vol2024/iss1/6