P364 Fat and glucose metabolism during exercise in patients with methylmalonic and propionic acidemia
Methylmalonic acidemia (MMA) and propionic acidemia (PA) are inherited metabolic disorders causing a deficiency in the catabolism of branched-chain amino acids, cholesterol, and odd-chain fatty acids. Both patient groups report exercise intolerance and fatigue. A previous case study found impaired l...
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| Published in: | Neuromuscular disorders : NMD Vol. 33; p. S186 |
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| Main Authors: | , , , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Elsevier B.V
01-10-2023
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| Online Access: | Get full text |
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| Summary: | Methylmalonic acidemia (MMA) and propionic acidemia (PA) are inherited metabolic disorders causing a deficiency in the catabolism of branched-chain amino acids, cholesterol, and odd-chain fatty acids. Both patient groups report exercise intolerance and fatigue. A previous case study found impaired lipolysis and blunted fat oxidation during exercise in a patient with PA, suggesting PA being a metabolic myopathy. This may partly explain the exercise intolerance and fatigue reported in the patient group. This study aimed to investigate fat and glucose metabolism during exercise in patients with PA and MMA. We included four patients, two patients with MMA and two with PA. The patients performed a submaximal exercise test on a cycle ergometer, working at a workload corresponding to 50% of their maximal oxygen capacity. Fat and glucose metabolism were quantified during exercise via continuous infusion of stable isotope-labeled glucose and palmitate (long-chain fatty acid) and indirect calorimetry. The results were compared to matched healthy controls. We found that all patients presented with impaired lipolysis, reflected by low lipolytic rate compared to healthy controls (1.5±0.3 vs. 4.0±0.4, p=0.005). The patients had low work capacity as illustrated by significantly higher perceived exhaustion (Borg scale) and heart rate than healthy controls (Borg: 13.8±0.3 vs. 8.0±0.4, p<0.001. Heart rate: 115.6±5.9 vs. 84.6±2.1, p=0.0004). Lastly, the patients could not increase their fat oxidation to the same extent as the healthy controls during exercise, reflected by the low mean rate of palmitate oxidation (0.8±0.3 vs 2.1±0.3, p=0.02). Our findings indicate that both PA and MMA should be considered metabolic myopathies, which may explain the reported exercise intolerance and fatigue. |
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| ISSN: | 0960-8966 1873-2364 |
| DOI: | 10.1016/j.nmd.2023.07.471 |