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Published on: September 23, 2015
Disorder in the serotonergic system due to tryptophan hydroxylation impairment: a cause of hypothalamic syndrome?
D A Schott1, J Nicolai, J E de Vries
1Department of Paediatrics, Maastricht University Medical Centre, Maastricht, The Netherlands. da.schott@mumc.nl
Background:
The hypothalamus regulates basic homeostasis such as appetite, circadian rhythm, autonomic and pituitary functions. Dysregulation in these functions results in the hypothalamic syndrome, a rare disorder of various origins. Since serotonin (5-HT) modulates most of the above-mentioned homeostasis, a defect in the serotonergic system can possibly participate in this syndrome.
Methods:
We describe a girl suffering from hypothalamic syndrome with a decreased concentration of 5-hydroxytryptophan (5-HTP) and a normal level of tryptophan in the cerebrospinal fluid (CSF) suggesting a functional defect in tryptophan hydroxylase (TPH). TPH is a rate-limiting enzyme in the synthesis of the neurotransmitter 5-HT.
Results:
Therapeutic intervention with 5-HTP, carbidopa and a specific serotonin reuptake inhibitor significantly improved her clinical symptoms and caused biochemical normalisation of neurotransmitters.
Conclusion:
The girl described had the typical symptoms of a hypothalamic disorder and a defective serotonergic metabolism, a relationship which has not been reported before. Therapeutic interventions to restore 5-HT metabolism resulted in clinical improvement. We suggest that investigation of 5-HT metabolism in CSF of patients with this rare disorder is included in the aetiological work-up.
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