La variante de la ataxia cerebelosa asociada con anticuerpos contra la descarboxilasa de ácido glutámico 65 (GAD-Ab) está relacionada con la diabetes mellitus tipo 1 (DM1). Presentamos el caso de una mujer de 63 años con ataxia cerebelosa de causa no identificada, que luego fue diagnosticada con DM1 y, gracias a la identificación de GAD-Ab en el líquido cefalorraquídeo, se demostró la asociación entre ambas patologías. El diagnóstico requiere demostrar el aumento en la síntesis intratecal de GAD-Ab. Resaltamos la importancia de considerar dentro de las causas de ataxia cerebelosa a la asociada con GAD-Ab, a fin de brindar un tratamiento oportuno y efectivo.

Introduction: Refractory hypothyroidism (RH) represents a challenge in the diagnosis and treatment within the field of thyroidology. It is defined as the inability to achieve disease control despite using levothyroxine (LT4) doses of 1.9 mg/kg/d or higher. Methods: A comprehensive review, encompassing 103 articles, was conducted using the Scielo, Scopus, and EMBASE databases, providing an approach to evaluation and diagnosis of this condition. Results: LT4 disintegrates and dissolves within an acidic gastric environment before being absorbed in the jejunum and ileum. It then extensively binds to serum transporter proteins and undergoes deiodination to yield tri-iodothyronine, the biologically active hormone. There are various nonpathological causes of RH, such as noncompliance with treatment, changes in the brand of LT4, food and drug interferences, as well as pregnancy. Pathological cau...