Evaluating Respiratory Enzyme Activity in Kidney Biopsies May Help Diagnose Mitochondrial Disease, Study Finds

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by Alice Melão |

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Mitochondrial diagnosis study

Determining the respiratory chain enzyme activity in kidney tissue samples could provide useful information for diagnosing mitochondrial dysfunction in children with renal impairment, according to a report in the Journal of Clinical Medicine.

Diseases stemming from mitochondrial dysfunction can be difficult to diagnose because of symptoms similar to other conditions. This often leads to misdiagnosis or delayed treatment of mitochondrial disorders.

Kidney problems are among the symptoms associated with mitochondrial disorders. They include poor re-absorption of bicarbonate, sodium, potassium, glucose, amino acids, and proteins.

These symptoms may not respond to steroids, and they may progress to kidney failure that can be treated only with a transplant.

Diagnosing mitochondrial diseases based only on kidney symptoms can be extremely challenging. Doctors often resort to examining other organs where mitochondria activity is crucial — such as the heart, muscles, and brain — for signs of mitochondria-related dysfunction.

Finding ways to link kidney symptoms more directly to mitochondrial disease could improve patient care.

Researchers at Birmingham Children’s Hospital in the United Kingdom wanted to know if they could use respiratory chain enzyme activity (RCEA) to measure mitochondrial function in kidney tissue biopsies. They also wanted to know if the enzyme activity could help them identify mitochondrial dysfunction in children with kidney problems.

Their study was titled “Measurement of Respiratory Chain Enzyme Activity in Human Renal Biopsy Specimens.

“The results of this study will provide pilot data for a more thorough validation study to assess the reliability of renal RCEA assessment as a diagnostic investigation,” the researchers wrote.

They assessed the activity of respiratory chain enzyme complexes I, II/III, and IV in 13 kidney tissue samples collected from children between 3 and 16 years old who had had routine renal biopsies.

The team discovered that it was possible to evaluate RCEA in all mitochondrial complexes, and that the activity in the different complexes was related.

They found no association between the age of the children and RCEA in kidney tissue. This suggested that kidney RCEA could be used as a biomarker regardless of age.

They also saw no relationship between an index of chronic kidney damage and RCEA values, suggesting that kidney RCEA reflects a healthy-tissue response. This finding indicates the test could be used in children with a suspected mitochondrial disorder and chronic kidney disease.

“We have shown that it is feasible to obtain samples from routine renal biopsies,” the researchers wrote. However, due to lack of samples from patients with a confirmed mitochondrial disease, it was not possible for them to determine which kidney RCEA values should be used as references when making diagnoses.

Additional studies with larger groups are necessary to establish a reference range and to confirm the diagnostic value of kidney RCEA, the researchers said.