On the basis of the first symptoms people usually go to their general physician. Mostly these first symptoms will be weakness of the muscles or unexplained fatigue. In many cases the general physician will try to find out the cause of these complaints. With respect to mitochondrial disease this will turn out to be a difficult road. A referral to a specialist (neurologist, paediatrician or internist/internal specialist) will be the next step. It is to be advised that the referral involves an appropriate expertise or research centre with a specific metabolic research laboratory.
When the symptoms point towards a suspicion of mitochondrial disease, different ways exist to establish the disease. In all cases the level of lactate in the blood and also in the brain liquids will be determined. The last is done by means of an epidural. Additionally, in most cases a urine sample is tested for lactate and other substances. Another kind of screening test is the exercise test with a home trainer or a treadmill, where the level of oxygen uptake is measured. By comparing these measurements with standards this will result in an indication into the cause of the disease.
In cases of intellectual disability or development issues a brain scan is done, usually a MRI scan. With DNA tests established and occurring mutations can be determined. Additionally, research into certain symptoms in the family (deafness, migraines, short stature) can be useful for a final diagnosis. For a final and complete diagnosis a biopsy of a small piece of muscle is required, with the purpose of testing it for mutated mitochondria. Such a biopsy can only be executed by qualified medical centres. Despite these methods many cases do not receive a specific diagnosis.
Mitochondrial disease is very difficult to diagnose and requires specialist knowledge. Therefore, it is essential for patients to find the appropriate research centre, which sometimes is not a simple task to do. Not all general physicians or clinicians are familiar with mitochondrial disease and know the way towards the right research centre. In addition, a single blood or urine lab test with normal results does not rule out a mitochondrial disease. This is true for organic acids, lactic acid, carnitine analysis and amino acid analysis. Even muscle biopsies are not 100% accurate.
If you wish to find the appropriate centre for diagnosis of mitochondrial disease, please contact your national patient organisation or contact IMP.
