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La Rivista Italiana della Medicina di Laboratorio 2020 Oct 07

DOI: 10.23736/S1825-859X.20.00077-8


lingua: Inglese

Defining lower reference values for serum total testosterone in males with indirect methods by the use of laboratory big data: a new approach to the diagnosis of late-onset hypogonadism

Renato TOZZOLI 1 , Paolo METUS 2, Maria Paola SIMULA 2, Elisa FADI 2, Federica D'AURIZIO 3, Marina VITILLO 4

1 Endocrinology Unit, S. George Clinic, Pordenone, Italy; 2 Clinical Pathology Laboratory, S. Maria degli Angeli Hospital, Pordenone, Italy; 3 Clinical Pathology Laboratory, University Hospital, Udine, Italy; 4 Clinical Pathology Laboratory, S. Filippo Neri Hospital, Rome, Italy


BACKGROUND: Late onset hypogonadism (testosterone deficiency) is a clinical syndrome, with a high incidence in Europe and United States, responsible of several adverse effects that induce a decreased quality of life in males. The diagnosis of the syndrome requires both clinical and biochemical criteria, in particular the demonstration of hypotestosteronemia. Establishing lower reference values of total testosterone is a critical issue, due to the biological and analytical variability of the steroid in healthy individuals: different international guidelines proposed different values ranging from 8.0 nmol/L to 10.4 nmol/L.
METHODS: Due to uncertainty to define lower reference values for total testosterone with classical CLSI direct methods, we performed an evaluation study of local population-based reference limits in two big Italian endocrine specialty laboratories (Pordenone and Rome) using the big current data stored in each laboratory information system and the Kairisto’s indirect method.
RESULTS: The results showed that the total testosterone concentration presents a near-gaussian distribution in the adults, the levels of the steroid decrease significantly during the adult age, starting from the age class 20-40 years, the central centile of the distribution is similar to those of the main studies in the world and the testosterone cutoff are much lower (with a percentage of 7-30%) in comparison with the proposed cutoffs for male hypogonadism in United Kingdom and in the United States.
CONCLUSIONS: The study confirms the need for each laboratory to define its own age-dependent reference values.

KEY WORDS: Total testosterone; Reference intervals; Late onset hypogonadism; Testosterone deficiency; Indirect methods; Big data

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