Características ultrassonográficas, funcionais e de autoimunidade tireoideana em lipodistrofia generalizada congênita

Abstract

High prevalence of insulin resistance (IR) is a public health problem. It is usually related to secondary abnormalities and thyroid appears to be affected by IR. Early and severe IR is a characteristic of Congenital Generalized Lipodystrophy (CGL), characterized by the near to total absence of subcutaneous adipose tissue. There are no studies about thyroid in CGL. The evaluation of these patients may allow a correlation between these two disorders, without obesity. OBJECTIVES: To describe thyroid structure and function in patients with CGL. METHODS: The study was performed in the outpatient clinics of Endocrinology and Metabology and Pediatric Endocrinology of Hospital Universitário Walter Cantídio. All patients with clinical diagnosis of LGG were included. The exclusion criteria were history exposure of iodinated contrast material in the previous six months, irradiation or neck surgery, pregnancy and nursing. The patients were submitted to a medical interview, physical examination, thyroid ultrasonography and collection of fasting blood samples for assay of glucose, leptin, basal insulin, total cholesterol, HDL cholesterol, triglycerides, thyroid stimulating hormone (TSH), free thyroxine (fT4), triiodothyronine (T3), antithyroperoxidase (ATPO) and anti-titreoglobulin (ATG) antibodies. HOMA-IR and LDL cholesterol were calculated. Fisher's exact test was used, Mann-Whitney, Spearman correlation, Program: stata 13. Significant p <0.05. Continuous quantitative variables were described in median (minimum and maximum); and qualitative, by proportions. RESULTS: Twenty-three patients with a diagnosis of LGG were included, median age was 13.3 years (3.6 to 38.7), 15 (65%) were younger than 19 years. In relation to sex, 14/23 (60.8%) were women. Fourteen (60.8%) patients had a diagnosis of diabetes mellitus. All presented phenotypic characteristics of CGL. The standard deviation (SD) of body mass index (BMI) in children and adolescents was 1 (0.11 - 1.59) and adult BMI was 22.2 kg / m² (19.3 - 25). All patients had low leptin and HDL cholesterol, 78,2% (18/23) hypertriglyceridemia (316.55-1052mg / dL). The prevalence of hormonal dysfunction was 17.4% (4/23), and subclinical (1/23) and clinical hypothyroidism (1/23), subclinical (1/23) and clinical hyperthyroidism (1 / 23). TSH was 1.27 uUI / mL (0.48 - 6.71), fT4, 1.06 ng / dL (0.82 - 1.92) and T3, 1.27 ng / dL (0, 69 - 1.76). The ATPO was positive in 4% (1/23) and the ATG in 17.3% (4/23). There was a negative correlation between HOMA-IR and fT4 (Spearman's r 0.036). The thyroid volume was 4.3 cm³ (1.04 - 60.4), it was altered in 19% of the patients, 33% had nodules and another 33%, parenchyma heterogenicity. There was a positive correlation between HOMA-IR and volume (Spearman's r 0.035). A case of thyroid carcinoma was diagnosed in an 8 years-old girl. CONCLUSION: The prevalence of abnormalities in thyroid structure and function was higher than in population data, especially in a young population. IR correlated positively with thyroid volume and negatively with T4l levels. This study did not show correlation between IR and autoimmunity. These data support that thyroid may be directly influenced by the high levels of insulin present in CGL.