7443 Severe Hypothyroidism and Adrenal Insufficiency in a 27-Year-Old Male with Klippel-Feil Syndrome: A Case Report

Abstract Disclosure: S. Almardini: None. F. Haddadin: None. L. Aoun: None. F. Saliba: None. J. Zaidan: None. Background: Klippel-Feil syndrome (KFS) is a rare congenital disorder characterized by improper segmentation of the cervical vertebrae. The classical clinical triad consists of short neck, low posterior hairline, and limited neck mobility. It is uncommonly associated with endocrine abnormalities. We present a rare case of KFS with severe primary hypothyroidism. Case Presentation: A 27-year-old male with KFS presented for evaluation of profound fatigue and lack of energy. His vital signs revealed a heart rate of 50 and a borderline low blood pressure. On physical exam patient was noted to be lethargic and icteric, thyroid exam was limited due to patient short neck. Labs were consistent with severe hypothyroidism TSH of 825 mIU/L, total T4 <0.4 mcg/dL, low 8 AM cortisol of 4.3 mcg/dL, elevated LDL at 333 mg/dL, elevated liver enzymes AST 491 U/L, ALT 294 U/L, neutropenia with WBC 2.69 x10^3/uL 20% neutrophils and anemia Hb 12 g/dL. TPO and thyroglobulin antibodies were positive at 149.0 and 109.0 IU/mL respectively, 21 hydroxylase antibodies were negative. Thyroid Ultrasound showed small and diffusely heterogenous thyroid. Patient was started on Levothyroxine 125 mcg daily and hydrocortisone with improvement in his symptoms as well as normalization of his lipid panel, liver enzymes and neutropenia. The patient was continued on levothyroxine 125 mcg, hydrocortisone was tapered and repeat cortisol levels were normal. Discussion: This case demonstrates an unusual association between KFS and hypothyroidism secondary to Hashimoto thyroiditis, likely representing an incidental finding rather than a causative relationship. The cervical spinal abnormalities and short neck characteristic of KFS could potentially lead to compression of neurological and vascular structures in the neck. However, this is unlikely to fully explain our patient's hypothyroidism. There are few published case reports of KFS with endocrine disorders in the literature that describe incidental findings like autoimmune thyroiditis and hypoparathyroidism, but there is no known biological mechanism linking KFS and endocrine dysfunction. Moreover, there is no evidence in either our patient's case or in existing literature to suggest a higher occurrence of autoimmune disorders like Hashimoto in such individuals. Conclusion: we present a novel case of KFS found incidentally with primary hypothyroidism. While these endocrine disorders could compound the growth delay and developmental issues typically seen in KFS, they do not appear to be causally related. This case highlights the need to monitor endocrine function in KFS patients and serves as a reminder that common conditions may co-occur simply by chance. Presentation: 6/3/2024