Tyrosine kinase inhibitors are used for the treatment of different types of tumours, interfering in various cell proliferation pathways, and tumour angiogenesis. These oral agents have side effects, thyroid dysfunction outstanding among them. There are different mechanisms through which these agents lead to hypothyroidism, as well as thyrotoxicosis. There is still no consensus on the treatment and follow-up of the above mentioned effects.

Los inhibidores de la tirosina cinasa son utilizados para el tratamiento de diversas neoplasias interfiriendo en múltiples vías de proliferación celular y angiogénesis tumoral. Estos fármacos presentan efectos adversos de clase, destacándose entre ellos la afectación de la función tiroidea. Existen diferentes mecanismos propuestos por los cuales estos agentes orales llevan tanto al hipotiroidismo como a la tirotoxicosis. Aún no existe consenso sobre el seguimiento y tratamiento ante la aparición de estos efectos.

ABSTRACT Objective To evaluate melatonin secretion in adult hypopituitary patients with Growth Hormone deficiency (AGHD) on and off replacement therapy. Subjects and methods We studied 48 subjects: 12 (6 males) untreated AGHD (AGHDnt), 20 (10 males) treated AGHD (AGHDt) and 16 healthy subjects (8 males) as control group (CG). We measured urinary 6-sulfatoxymelatonin (6-SM) in total (24 h samples), nocturnal (6-SMn): 1800-0800 and diurnal samples (6-SMd): 0800-1800. Results Significant differences were observed among the 3 groups of male subjects, in total 6-SM (p < 0.05), nocturnal 6-SM (p < 0.02) and nighttime-daytime delta values (p < 0.003). CG had significantly higher values than the AGHDnt in total 6-SM (p < 0.01), nocturnal 6-SM (p < 0.05) and nighttime-daytime delta values (p < 0.01). AGHDt patients showed significantly higher levels in nighttime-daytime delta values than AGHDnt patients (p < 0.05). In females, no significant differences were found among the 3 groups studied in total, nocturnal, diurnal or nighttime-daytime delta values. In males, significant correlations were found among total 6-SM (r = 0.58; p = 0.029), nocturnal 6-SM (r = 0.70; p = 0.006) and nighttime-daytime delta values (r = 0.71; p = 0.004) vs. serum IGF-1 levels in subjects evaluated. In females, significant correlations were found among total 6-SM (r = 0.57; p = 0.02) vs. serum IGF-1 levels in subjects evaluated. A tendency towards a significant correlation was found in diurnal 6-SM (r = 0.48; p = 0.07). Conclusions Our findings show a sexual dimorphism in 6-SM excretion in AGHD patients and provide an interesting approach to a further understanding of some chronobiological disorders involved in GH deficiency.