SAT-356 Unexpected Recovery of Renal Function After Treatment of Incidentally Discovered Hypothyroidism

Abstract Disclosure: H.K. Boparai: None. A. Randhawa: None. M. Sattar: None. Hypothyroidism and hyperthyroidism are both known to be associated with alterations in cardiac output and vascular resistance. Additionally, decreased vascular endothelial growth factor is noted with hypothyroidism. Immunocomplexes may also be deposited in the basement membrane of glomeruli in autoimmune thyroid disorders. All these mechanisms have previously been known to contribute to renal function derangements. Our case is about a 21-year-old female who went for a pre-employment checkup and was incidentally found to have a TSH of 368 with a free T4 <0.25. She was referred to an endocrinology clinic for further evaluation and management of hypothyroidism. During the interview, she reported some hair thinning, cold intolerance, fatigue, and irregular periods in the past few months. Her family history revealed that her maternal grandmother and aunt had thyroid disease. Concurrently, her labs also revealed an elevated creatinine of 1.8, along with albuminuria, prompting a referral to a nephrology clinic. Renal Doppler and urinalysis were unremarkable. A repeat set of TSH and T4, along with Thyroid peroxidase (TPO) antibody confirmed the diagnosis of hypothyroidism (elevated TSH, severely suppressed T4, and a positive TPO antibody) and she was started on a weight-based dose of levothyroxine 75 mcg daily. On follow-up visits, the patient’s thyroid hormone levels improved significantly and returned to normal, and her creatinine level also improved, coinciding with the initiation of thyroid hormone supplementation. The patient’s fatigue, cold intolerance, hair loss, and menstrual periods returned to normal with Levothyroxine administration. Since the patient’s kidney function returned to normal, a decision was made not to pursue a kidney biopsy or any further investigations, so the cause of the initial kidney disease remains uncertain. While thyroid hormone supplementation has been previously shown to delay the progression of chronic kidney disease, our case highlights an unusual complete resolution of significant kidney disease in a young, otherwise healthy individual after thyroid hormone supplementation. Literature suggests that hypothyroidism can cause renal dysfunction but also that renal dysfunction itself, in particular, nephrotic syndrome can cause hypothyroidism. In this patient, it is uncertain if protein losses from kidney disease contributed to her significant hypothyroidism or if the thyroid disease contributed to the kidney disease. This case not only highlights the importance of diagnosing and treating hypothyroidism with a subtle clinical presentation, but also explores the association between renal dysfunction and thyroid disease, and the need to investigate secondary causes of these disorders. Presentation: Saturday, July 12, 2025