Glossary

ultrasound
an imaging technique used to examine organs, in which ultrasound waves are sent through the skin into the body; at tissue and organ boundaries, the sound waves are reflected back, picked up by a receiver (transducer) and converted into corresponding images with the help of a computer.

undifferentiated
here: immature, not yet functional and usually capable of unlimited division (e.g. stem cells); the development from undifferentiated to differentiated cells and tissues (differentiation) takes place in stages. Accordingly, there are many different degrees of differentiation.
Example / Relevance Pediatrics: the degree of differentiation of cancer cells refers to their similarity or difference to healthy, functional cells of the organ in which the tumour originated: highly differentiated cancer cells largely resemble normal cells, while undifferentiated cancer cells differ greatly from them. As a rule, the more undifferentiated a tumour is, the more malignant it is.

Undine syndrome syn. congential central hypoventilation syndrome
a rare congenital disease of the central nervous system associated with a disorder of respiratory regulation; in addition, there are other dysregulations (such as cardiac arrhythmias, swallowing disorders, body temperatures that are too high or too low, formation of tumours). About a quarter of children with this syndrome also suffer from Hirschsprungs disease.
Example / Relevance Pediatrics: patients with Undine syndrome may develop tumours of the nervous system (neuroblastomas and ganglioneuroblastomas).

urea
a component of urine produced in the liver (in the so-called urea cycle) and excreted by the kidneys; an important end product of protein metabolism; urea is used to detoxify the metabolic toxin ammonia, which is produced during the breakdown of amino acids.
Example / Relevance Pediatrics: elevated urea levels may indicate poor or absent kidney function (renal insufficiency) and may occur as a side effect and/or complication of some cancers and their treatment. Urea determination is mainly carried out as part of diagnostic testing and follow-up monitoring in patients with renal insufficiency.
References: protein

uric acid
end product of purine metabolism (as part of nucleic acid degradation); is largely excreted by the kidneys;
Example / Relevance Pediatrics: elevated uric acid levels in the blood (hyperuricaemia) occur with increased cell breakdown (e.g. in leukaemia and lymphoma as a consequence of chemotherapy, so-called tumour lysis syndrome). If tumour lysis is not managed appropriately, severe kidney damage will occur.
References: leukaemia - lymphoma - tumour lysis syndrome - chemotherapy