Inborn errors of metabolism

The diagnosis of inborn errors requires in addition to a thorough assessment of the medical history and clinical examination specialised diagnostic testing, including biochemical and molecular tests. Genetic counselling should be offered to all families due to the increased recurrence risk for future pregnancies. Basic diagnostic testing of blood (full blood count, electrolytes, glucose, acid-base status, creatine kinase, triglycerides, lactate and ammonium) as well as of urine (urine dipstick for glucose, protein and ketone bodies) will give a first impression as to whether an inborn error of metabolism may be likely. Importantly, additional samples should be drawn during the acute presentation prior to initiation of treatment and stored until further analysis. Some variants and atypical forms of inborn errors of metabolism may not be detected by newborn screening. If such a disorder is suspected clinically specific metabolic testing should be initiated even following a normal newborn screening result. It should also be kept in mind that newborn screening programmes only screen for a limited number of inborn errors of metabolism and that a normal screening result does not preclude the diagnosis of an inborn error of metabolism.