VMVirgilio Melgar

Virgilio Melgar

*This is an algorithmically generated author record based on publicly available information.

Current Organizations / Institutes

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Previous Organizations / Institutes

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Virgilio Melgar has a total of 48 co-authors. Here are the top co-authors by number of shared publications:


Latest Publications

  • An Update on Gastroenteropancreatic Neuroendocrine Neoplasms: From Mysteries to Paradigm Shifts

    by Claudia Ramírez-Rentería, Aldo Ferreira-Hermosillo, Daniel Marrero-Rodríguez, Keiko Taniguchi-Ponciano, Virgilio Melgar-Manzanilla, Moisés Mercado


  • Open Access

    An FSH and TSH pituitary adenoma, presenting with precocious puberty and central hyperthyroidism

    by Guadalupe Vargas, Lourdes-Josefina Balcazar-Hernandez, Virgilio Melgar, Roser-Montserrat Magriña-Mercado, Baldomero Gonzalez, Javier Baquera, Moisés Mercado

    A 19-year-old woman with a history of isosexual precocious puberty and bilateral oophorectomy at age 10 years because of giant ovarian cysts, presents with headaches and mild symptoms and signs of hyperthyroidism. Hormonal evaluation revealed elevated FSH and LH levels in the postmenopausal range and free hyperthyroxinemia with an inappropriately normal TSH. Pituitary MRI showed a 2-cm macroadenoma with suprasellar extension. She underwent successful surgical resection of the pituitary tumor, which proved to be composed of two distinct populations of cells, each of them strongly immunoreactive for FSH and TSH, respectively. This mixed adenoma resulted in two different hormonal hypersecretion syndromes: the first one during childhood and consisting of central precocious puberty and ovarian hyperstimulation due to the excessive secretion of biologically active FSH and which was not investigated in detail and 10 years later, central hyperthyroidism due to inappropriate secretion of biologically active TSH. Although infrequent, two cases of isosexual central precocious puberty in girls due to biologically active FSH secreted by a pituitary adenoma have been previously reported in the literature. However, this is the first reported case of a mixed adenoma capable of secreting both, biologically active FSH and TSH. Learning points: Although functioning gonadotrophinomas are infrequent, they should be included in the differential diagnosis of isosexual central precocious puberty. Some functioning gonadotrophinomas are mixed adenomas, secreting other biologically active hormones besides FSH, such as TSH. Early recognition and appropriate treatment of these tumors by transsphenoidal surgery is crucial in order to avoid unnecessary therapeutic interventions that may irreversibly compromise gonadal function.


    • 16 March 2017
      • Vol. 55  (2) , 214-222

    [Autism spectrum disorder: Etiological, diagnostic and therapeutic aspects].

    by César Reynoso, María José Rangel, Virgilio Melgar

    Autism spectrum disorder (ASD) was described for the first time in 1943 by Leo Kanner, and since 2004, 18 490 articles in the subject have been published, which in turn have been cited 48 416 times.1 Almost half of these publications come from the United States of America and the vast maority of the efforts to improve the quality of life of these patients have taken place in developed countries. This disorder consists of an inability to acquire social and emotional skills during early development that progressively results in variable degrees of social adaptation discapacity. The etiology is multifactorial and includes functional and structural neurological abnormalities, some of them with putative genetic and/or epigenetic origin. There is an alarming lack of knowledge in the subject among health care professionals. The purpose of this systematic review is to summarize the most relevant historical, diagnostic and therapeutic aspects of ASD.


  • The Mexican Acromegaly Registry: Clinical and Biochemical Characteristics at Diagnosis and Therapeutic Outcomes

    by Lesly A. Portocarrero-Ortiz, Alma Vergara-Lopez, Maricela Vidrio-Velazquez, Ana María Uribe-Diaz, Avril García-Dominguez, Alfredo Adolfo Reza-Albarrán, Daniel Cuevas-Ramos, Virgilio Melgar, Juan Talavera, Aleida de Jesus Rivera-Hernandez, et al.

    Context: Acromegaly is a systemic disorder caused by a GH-secreting pituitary adenoma. As with other rare diseases, acromegaly registries developed in various European countries have provided us with important information. Objective: The objective of the study was to analyze the epidemiological, clinical, biochemical, and therapeutic data from the Mexican Acromegaly Registry (MAR). Setting: The setting of the study was a nationwide patient registry. Design and Methodology: The MAR was created in 2009. It gathers data from 24 participating centers belonging to three different institutions using a specifically designed on-line platform. Only patients diagnosed after 1990 were included in the program. Results: A total of 2057 patients (51% female, mean age at diagnosis 41.1 ± 24.5 y) have been registered for an estimated prevalence of 18 cases per 1 million inhabitants. Hypertension, glucose intolerance, diabetes, and dyslipidemia were present in 27%, 18.4%, 30%, and 24% of the patients, respectively. The IGF-1 level at diagnosis and the concomitant presence of hypertension were significantly associated with the development of diabetes. Transsphenoidal surgery was the primary treatment in 72% of the patients. Pharmacological treatment, mostly with somatostatin analogs, was administered primarily and adjunctively in 26% and 54% of the patients, respectively. Treatment choice varied among the three participating institutions, with the predominance of pharmacological therapy in two of them and of radiation therapy in the third. Therapeutic outcomes were similar to those reported in the European registries. Conclusions: The MAR is the largest and first non-European registry of the disease. Our findings highlight important within-country differences in treatment choice due to variations in the availability of resources.


  • AIP mutations in young patients with acromegaly and the Tampico Giant: the Mexican experience

    by Claudia Ramírez-Rentería, Laura C. Hernández-Ramírez, Lesly Portocarrero-Ortiz, Guadalupe Vargas, Virgilio Melgar, Etual Espinosa, Ana Laura Espinosa-De-Los-Monteros, Ernesto Sosa, Baldomero González, Sergio Zúñiga, et al.

    Although aryl hydrocarbon receptor-interacting protein (AIP) mutations are rare in sporadic acromegaly, their prevalence among young patients is nonnegligible. The objectives of this study were to evaluate the frequency of AIP mutations in a cohort of Mexican patients with acromegaly with disease onset before the age of 30 and to search for molecular abnormalities in the AIP gene in teeth obtained from the “Tampico Giant”. Peripheral blood DNA from 71 patients with acromegaly (51 females) with disease onset T (p.Arg304Ter), well-known truncating mutation was identified; in one of these two cases and her identical twin sister, the mutation proved to be a de novo event, since neither of their parents were found to be carriers. In the remaining three patients, new mutations were identified: a frameshift mutation (c.976_977insC, p.Gly326AfsTer), an in-frame deletion (c.872_877del, p.Val291_Leu292del) and a nonsense mutation (c.868A > T, p.Lys290Ter), which are predicted to be pathogenic based on in silico analysis. Patients with AIP mutations tended to have an earlier onset of acromegaly and harboured larger and more invasive tumours. A previously described genetic variant of unknown significance (c.869C > T, p.Ala299Val) was identified in DNA from the Tampico Giant. The prevalence of AIP mutations in young Mexican patients with acromegaly is similar to that of European cohorts. Our results support the need for genetic evaluation of patients with early onset acromegaly.


    • 29 January 2016
      • Vol. 54  (1) , 111-21

    [Current diagnosis and treatment of hyperprolactinemia].

    by Virgilio Melgar, Etual Espinosa, Ernesto Sosa, María José Rangel, Dalia Cuenca, Claudia Ramírez, Moisés Mercado

    Hyperprolactinemia is a frequent neuroendocrinological condition that should be approached in an orderly and integral fashion, starting with a complete clinical history. Once physiological causes such as pregnancy, systemic disorders such as primary hypothyroidism and the use of drugs with dopamine antagonistic actions such as metochlopramide have been ruled out, the most common cause of hyperprolactinemia is a PRL-secreting pituitary adenoma or prolactinoma. Prolactinomas are usually classified as microprolactinomas (less than 1 cm) or macroprolactinomas (larger than 1 cm), which can either be confined or invasive. The hormonal consequence of hypeprolactinemia is hypogonadism; in women, this is manifested as amenorrhea/oligomenorreha, anovulation and galactorrhea, whereas in men the main complaints are a diminished libido and erectile dysfunction. Macroprolactinomas can also present with symptoms and signs resulting form mass effect of the tumor, such as headaches and visual field defects. Other structural causes of hyperprolactinemia include non-functioning pituitary adenomas and infiltrative disorders, which can interrupt the inhibitory, descending dopaminergic tone. The primary treatment of prolactinomas is pharmacological with dopamine agonists such as cabergoline.


  • Giant prolactinomas: are they really different from ordinary macroprolactinomas?

    by Etual Espinosa, Ernesto Sosa, Victoria Mendoza, Claudia Ramírez, Virgilio Melgar, Moisés Mercado

    Giant prolactinomas (gPRLomas) are rare tumors of the lactotroph defined by an unusually large size (>4 cm) and serum PRL levels >1000 ng/mL. The purpose of this study is to characterize the clinical spectrum of gPRLomas comparing them with non-giant prolactinomas. This is a retrospective study at a large referral center. Data from patients harboring gPRLomas and macroprolactinomas were retrieved from medical records of the Prolactinoma Clinic. Analysis was focused on clinical, biochemical, and tumor volume characteristics, as well as on the response to treatment with dopamine agonists. Among 292 patients with prolactinomas followed between 2008 and 2015, 47 (16 %) met the diagnostic criteria for gPRLomas (42 males). The most common complaint was a visual field defect; headache was reported by 79 % and sexual dysfunction was present in over half of the patients. Median basal PRL level and tumor volume were 6667 ng/mL (3750–10,000) and 32 cm3 (20–50), respectively; hypogonadotropic hypogonadism was documented in 87 %. Cabergoline treatment resulted in the normalization of PRL levels in 68 % and in the reduction of >50 % in tumor volume in 87 % of the gPRLoma patients. The composite goal of PRL normalization and >50 % tumor reduction was achieved by 55 % (n = 26) of patients with gPRL and by 66 % (n = 100) of patients with no giant macroprolactinomas (p = 0.19). Recovery of hypogonadism and improvement of visual fields defects occurred in 32 % and 68 % of the patients, respectively. Cabergoline treatment was equally effective in patients with gPRLoma and those with macroprolactinomas in regard of achieving treatment goals, although the median CBG dose was slightly higher in the gPRLoma group (2 vs. 1.5 mg/w). Six patients required surgery. Beyond their impressive dimensions and the huge amount of PRL they secrete, the clinical behavior of gPRLoma is not different from macroprolactinomas. These tumors are highly responsive to cabergoline treatment, and pituitary surgery is seldom required.


    • 15 February 2015
      • Vol. 53  (1) , 74-83

    [Current diagnosis and treatment of acromegaly].

    by Virgilio Melgar, Etual Espinosa, Dalia Cuenca, Vanessa Valle, Moisés Mercado

    Acromegaly is a rare condition characterized by the excessive secretion of growth hormone (GH), usually by a pituitary adenoma. The clinical manifestations of acromegaly include enlarged hands, feet and face, headaches, arthralgias, fatigue and hyperhydrosis. This condition is also associated with comorbidities such as hypertension and diabetes in a significant proportion of patients and frequently compromises life quality and life expectancy. The biochemical diagnosis of acromegaly rests on the demonstration of an autonomous secretion of GH by means of the measurement of glucose-suppressed GH levels and the serum concentration of insulin like growth factor type 1 (IGF-1). The localizing method of choice is magnetic resonance image of the selar area, which in 70 % of the cases reveals the presence of a macroadenoma. Even though the primary treatment is usually the transsphenoidal resection of the adenoma, the majority of patients require a multimodal intervention that includes radiotherapy, as well as pharmacological therapy with somatostatin analogs and dopamine agonists. The latter approach has resulted in a significant reduction in mortality and in an improvement in the quality of life.