Diagnosis
To make the diagnosis of an OAD or a UCD can be very simple in some patients but extremely laborious in others.
There are few metabolites which are highly specific for single disorders and if these can be identified, the diagnosis is almost certain. Examples are:
- Presence of both urinary glutaric acid and 3-hydroxyglutaric acid for glutaric aciduria type 1
- Presence of even small amounts of argininosuccinic acid in blood or urine for argininosuccinic aciduria
More often, it is the combination of clinical presentation and metabolite profiles that lead to the suspicion of any OAD or UCD. Then, further test are required such as enzyme or mutation analysis. A detailed description of the metabolic work-up of OADs and UCDs can be found on this website.
There are only few key metabolic investigations that should be done in a patient with a suspicion of an OAD or UCD:
- In blood: ammonia, amino acids, acylcarnitines
- In urine: ketone bodies, organic acids, orotic acid
To establish the diagnosis of an OAD or UCD requires in first place to think of these disorders. It is known from many patients that the time to diagnosis was very long mostly because OADs or UCDs have not been on the first list of differential diagnosis. Thus, an increased awareness of all healthcare professionals is necessary to improve the time to diagnosis in unknown patients.