MON-763 The relationship between folate, calcium and parathyroid hormone in patients with and without primary hyperparathyroidism: A National Health and Nutrition Examination Surgery (NHANES) study

Abstract Disclosure: L. Collado: None. F.J. Bennett: None. K.M. Oppat: None. V.J. Muralidharan: None. A.S. Jackson: None. S.G. Patel: None. N. Saunders: None. C. Weber: None. J. Sharma: None. T. Yamashita: None. Introduction: Folate is a vitamin that has been linked to altered metabolism in abnormal tissue growth and different types of neoplasia. In primary hyperparathyroidism (PHPT) abnormal growth of parathyroid gland(s) in the form of an adenoma, multigland disease, or rarely, carcinoma, leads to autonomous overproduction of parathyroid hormone (PTH), resulting in elevated serum calcium (Ca) levels. A correlation between folate levels and PHPT has not previously been studied. Methods: Using the National Health and Nutrition Examination Survey (NHANES) database, we identified patients (pts) with and without PHPT, defined as either PTH ≥ 65pg/mL with Ca ≥ 10.2mg/dL or as Vitamin D >30ng/mL and Ca≥ 10.2mg/dL in pts without available PTH levels. Logistic regression was used to evaluate the relationship between serum folate (Sf) and Red Blood Cell folate (RBCf) and Ca and PTH levels. Given cohort size discrepancy, PHPT pts were matched 1:2 to pts without PHPT based on demographics. Results: Of the 96,374 pts identified within the NHANES dataset from 2003-2016, 402 (0.42%) were identified to have PHPT and 95,972 (99.58%) did not. The mean age was 31.1 overall, 31.0 for non-PHPT and 39.8 for PHPT. Sex distribution was 50.8% female and 49.2% male. Within the total cohort, RBCf had a negative linear correlation with Ca (p<0.05) and positive linear correlation with PTH (p<0.05). Sf demonstrated a positive linear correlation with Ca (p<0.05) overall. This relationship held true within the non-PHPT cohort of unmatched pts only. When comparing PHPT to non-PHPT, the mean RBCf was higher in the non-PHPT cohort (102.64ng/mL vs. 155.63ng/mL, p< 0.05), while the mean Sf was higher in the PHPT cohort (28.08ng/mL vs. 9.4ng/mL, p< 0.05). RBCf had a positive linear correlation with Ca and PTH in the PHPT cohort (p< 0.05) while in the non-PHPT cohort there was a negative linear correlation with Ca (p=0.78) and PTH (p=0.3). Sf had a negative linear correlation on Ca (p=0.55) in the PHPT cohort yet a positive linear correlation on Ca (p=0.08) in the non-PHPT cohort. Conclusion: Significant differences were identified in serum levels and relationships between folate, Ca and PTH in pts with and without PHPT. Although mean RBCf was lower in PHPT, it presented a positive linear correlation with Ca and PTH, the opposite of what was seen in the non-PHPT cohort. Interestingly, Sf had the opposite effect on Ca; positive on non-PHPT and negative on PHPT. This suggests folate metabolism may be altered in parathyroid cells in PHPT, but additional studies are required to elucidate the exact mechanism driving this relationship and if causality exists. Presentation: Monday, July 14, 2025