Less Known and Neglected Renal Complication of Primary Hyperparathyroidism: Renal Cysts

INTRODUCTION: Simple renal cysts are lesions that are epithelial in origin, with a prevalence changing between 5 to 15% in the normal population. In animal studies, it was shown that PTH might stimulate cyst formation via intracellular signaling systems triggering epithelial cell proliferation. Our primary aim was to detect the simple cyst prevalence in a large cohort of PHPT and compare it with sex and age-matched health individuals. The secondary aim was to detect determinants of cyst formation in PHPT.
METHODS: A total of 307 PHPT patients and 112 healthy controls were enrolled in our study. PHPT group was compared with the control group regarding the biochemical parameters and presence, size and bilaterality of renal cysts in the US performed by a single experienced radiologist.
RESULTS: Prevalence (43.65% vs 25%, p=0.020) and size [28.40 mm (min-max: 4-82) vs 12.20 mm (min-max: 3-94) (p=0.013)] of simple renal cysts were higher in the PHPT group compared to controls. The presence of renal cysts was correlated with age but not sex and positively correlated with the serum PTH level in regression analysis. Serum Ca, P, and 24-hour urinary Ca excretion were not found to be associated with cyst formation.
DISCUSSION AND CONCLUSION: Simple renal cysts are a benign renal complication of PHPT that does not alter renal function significantly, and their presence is directly correlated with the hypersecretion of PTH.