Congratulations Dr. Helena Rodríguez González
In important day
Today, July 9, 2026, Helena Rodríguez González successfully defended her doctoral thesis — Statistical characterization of laboratory results in pediatric patients for the establishment of reference intervals: a methodological framework for clinical laboratory interpretation — within the Programa de Doctorat en Enginyeria Biomèdica at the Universitat Politècnica de Catalunya.
On behalf of the entire B2SLab team, I want to extend our warmest congratulations to Dra. Helena Rodríguez González. This defence is the culmination of years of rigorous, clinically grounded, and genuinely important work.
A collaboration between two laboratories
This thesis is the fruit of an especially meaningful partnership. Helena’s work was co-directed by Rafael Artuch Iriberri, head of the Laboratory of Inborn Errors of Metabolism at Hospital Sant Joan de Déu, and Alexandre Perera Lluna, head of B2SLab at the Institut de Recerca i Innovació en Salut (IRIS) of the Universitat Politècnica de Catalunya.
The image of Rafa and Àlex together after the defence speaks to something beyond formality. This collaboration between a world-class clinical metabolic laboratory and a biomedical signals and bioinformatics research group is exactly the kind of interdisciplinary bridge that makes impactful translational research possible. Clinical expertise in rare metabolic diseases on one side; statistical and computational methodology on the other. Helena worked perfectly at that intersection, and the result is a thesis that is as relevant at the hospital bench as it is in the methods literature.
We are proud of what we have built together with the Sant Joan de Déu team, and grateful for a collaboration built on mutual respect, shared curiosity, and a genuine commitment to improving the lives of children with rare diseases.
About the context
Interpreting biochemical laboratory results in pediatric patients is harder than it sounds. Children are not small adults — their metabolism changes rapidly across development, creating a strong age dependency in almost every measurable biomarker. At the same time, many of the analytes most relevant to rare metabolic disease diagnosis (cerebrospinal fluid neurotransmitters, amino acids, trace elements) are measured in populations where true healthy controls are difficult or impossible to obtain: you do not routinely perform a lumbar puncture on a healthy child.
These challenges — age dependency, confounding factors like medication or inflammation, and the absence of reference healthy cohorts — make it unreliable to use traditional stratified reference intervals for clinical decision-making. Patients may be misclassified; real deficiencies may be missed; false positives generate unnecessary anxiety and follow-up.
Helena’s thesis develops a unified statistical framework to address these problems, validated across three distinct clinical use cases.
Three studies for a unique methodological thread
CSF neurotransmitters: defining normality without healthy controls
The first study addressed cerebrospinal fluid (CSF) concentrations of homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) — the end products of dopamine and serotonin metabolism, respectively — in a cohort of 1,533 pediatric patients. Since lumbar puncture is not performed in healthy individuals, there are no true healthy controls for these analytes. Helena applied regression models to capture age dependency and Gaussian mixture models to discriminate between deficient and non-deficient subpopulations within the patient data itself. The resulting continuous reference intervals more accurately reflect biological reality and reduced the detection of secondary alterations without clinical significance.
CSF amino acids in epilepsy: medication matters
In a second study, Helena characterised the CSF amino acid profile in a cohort of 410 neuropediatric patients including children with epilepsy and neurological controls. Age-adjusted reference intervals were established, and the impact of antiepileptic medication on individual amino acid levels was assessed using regression and multivariate models. The results showed a pronounced pharmacological effect — particularly on glutamine — that would be invisible if medication were not accounted for. This has direct implications for how clinicians should interpret amino acid profiles in children on chronic medication.
Serum copper: inflammation as a confounder
The third study turned to blood and addressed serum copper reference intervals in a cohort of 1,141 pediatric patients. Copper presents a specific additional challenge: inflammation elevates ceruloplasmin (the main copper-carrying protein), which drives up measured copper concentrations. A child with an ongoing infection or chronic inflammatory condition may appear copper-replete while actually being at risk of deficiency. Helena constructed a composite inflammatory index using partial least squares regression on three acute-phase biomarkers (ESR, fibrinogen, CRP), incorporated it into the age-continuous reference model, and demonstrated that inflammation accounts for approximately 24% of residual variability in measured copper. The result is the first age- and inflammation-adjusted reference model for paediatric serum copper.
It matters
Across all three studies, the message is consistent: reference intervals in paediatrics must account for continuous age effects, clinical confounders, and the structure of the available data — which is rarely from healthy populations. Helena’s framework is not only methodologically sound; it is transferable. The same statistical approach can be extended to other analytes and other clinical contexts, providing a reusable toolkit for the interpretation of paediatric biomarkers in rare disease.
This is the kind of work that does not generate headlines but changes daily clinical practice, quietly and durably.
Helena brought to this project not only statistical talent but also a clarity of purpose. Working at the interface of a clinical laboratory and an engineering research group requires intellectual flexibility, and she navigated that space with grace and determination. It has been a real privilege work with her during this perior.
We are equally grateful to Rafa and the entire Sant Joan de Déu team for the years of shared dedication that made this possible.
Congratulations, Dra. Rodríguez González :)
/Àlex