MO033: Parathyroid hormone determination as an early predictor of progression in autosomal dominant polycystic kidney disease

Abstract

BACKGROUND AND AIMS Total kidney volume (TKV) in patients with autosomal dominant polycystic kidney disease (ADPKD) is a known progression factor in these patients. Low levels of klotho and high levels of FGF23 in the blood of patients with ADPKD have been correlated with higher TKV even in early stages of the disease, even with glomerular filtration rate (eGFR) >90 mL/min/1.73 m2. Therefore, alterations in the levels of parathyroid hormone (PTH), vitamin D, tubular reabsorption of phosphates or urinary calcium could be correlated with the TKV and serve as an early serum biomarker of progression of kidney disease. METHOD Observational, cross-sectional, single-center study in a population of 87 patients under follow-up at our center during 2019–2020 for ADPKD. The TKV, obtained by the ellipsoid formula measured by magnetic resonance imaging (MRI) and the values of PTH, vitamin D, tubular phosphate reabsorption and urinary calcium were retrospectively collected. Subsequently, a statistical analysis of correlation between the different variables was performed. RESULTS Spearman's Rho correlation analysis obtained a positive correlation of moderate–strong intensity between the TKR of the sample and PTH levels (r = 0.638, P <0 0.0001) and a negative correlation of moderate intensity with tubular phosphate reabsorption (r = −0.479, P < 0.005). No statistically significant correlation was obtained between the TKV and the levels of urinary calcium or serum vitamin D. TKV was higher among patients with an eGFR >90 mL/min/1.73 m2 (CKD-EPI) with an elevated PTH (> 65 pg/mL), with a median of 530 mL (interquartile range 403–1184 mL), compared with the TKV of those patients with an eGFR >90 mL/min/1.73 m2 with normal PTH, whose median was 405 mL (interquartile range 258–576 mL). Despite this trend, the Mann–Whitney U test did not show a statistically significant difference between medians in the subgroup of patients with eGFR >90 mL/min/1.73 m2. However, the comparison of medians in the subgroup of patients with eGFR <90 mL/min/1.73 m2 was statistically significant with a P < 0.019, with higher TKR in those patients with high PTH. CONCLUSION The increase in PTH in patients with ADPKD has a strong positive correlation with TKV. Even with normal eGFR, elevated PTH is associated with a higher TKV, which could be an early serum biomarker of kidney disease progression in this group of patients.

Kidney Stones Account for Increased Imaging Studies in Autosomal Dominant Polycystic Kidney Disease

“…Parathyroid hormone may be an early predictor of progression in ADPKD, 21 which may explain why we saw more primary hyperparathyroidism in the ADPKD cohort despite matching for CKD stage. If our ADPKD cohort is a higher risk population, it may not accurately represent a broader ADPKD population.…”