Higher rates of hypothyroidism have been identified in patients with degenerative spine disease. This study examines the rate of hypothyroidism in patients with adult spinal deformity and aims to identify any potential relationships between Cobb angle and markers of thyroid dysfunction.In this multi-center retrospective study, adults aged 60 years or older with imaging evidence of spinal deformity as measured by Cobb angle from August 2015 to November 2024 were reviewed. Demographic data, hypothyroidism diagnosis, and thyroid panel values were obtained from medical records. Imaging was used to identify spinal deformity, Cobb angle, and bone mineral density.Among 834 patients, the mean age was 80 years, with 596 females. Adult spinal deformity patients were subcategorized into adult degenerative scoliosis (80.3%) and adolescent idiopathic scoliosis that progressed into adulthood (19.7%) with an average Cobb angle of 18.3° and 28.4°, respectively. Hypothyroidism was diagnosed in 278 patients (33.3%). Hypothyroidism, an increase of 1 mIU/L in TSH, and female gender were significantly associated with severity of disease as measured by an increase in Cobb angle in patients with adult degenerative scoliosis. Neither hypothyroidism, TSH, nor free T4 was not associated with worsened bone mineral density.The prevalence of hypothyroidism was higher in patients with adult spinal deformity compared to the general population. Hypothyroidism, TSH values, and female gender were significantly associated with larger Cobb angles. Bone mineral density was not associated with Cobb angle. Future studies are needed to understand the relationship between hypothyroidism and spinal deformity.