Renal excretion function in primary hyperparathyroidism: cardio-renal syndrome

Abstract

Background. Primary hyperparathyroidism (PHPT) is an endocrine disease, due to the formation of excess parathyroid hormone secretion and a disturbance of phosphorus-calcium metabolism. PHPT is associated with reduced renal function and related increased mortality, therefore renal function impairment defined as a glomerular filtration rate (GFR) less than 60 mL/ min/1.73 m 2 is considered as an indication for surgical treatment. Some patients with PHPT have secondary cardio-renal syndrome (type 5), which is characterized by the presence of combined renal and cardiac pathology. THE AIM: Evaluate the GFR in patients with mild and symptomatic PHPT and its changes after parathyroidectomy and on medical treatment. Patients and methods : A cross-sectional comparative and prospective study was conducted on 100 patients with confirmed PHPT. A clinical and laboratory examination was performed at 6, 12, and/or 24 months and included an assessment of the PHPT complications as well as expression of cardio-renal syndrome according to the selected management tactics. Changes in GFR were evaluated in 29 patients after surgical treatment and in 27 patients on conservative management. Glomerular filtration rate was calculated by the Modification of Diet in Renal Disease Study (MDRD) formula. The chronic kidney disease (CKD) stage was estimated accordingly to current recommendations. Results: We included 100 patients (10 men and 90 women) with PHPT: 33 with mild and 67 with symptomatic PHPT. The median age was 57 years [51;61]. Mean GFR was 84,1 [73,3; 97,9] ml/ min/1,73 m 2 . Prevalence of CKD 3-4 in patients with PHPT was recorded at 11 %. Patient management tactics were determined in accordance with international recommendations. In the long-term period after surgery, we observed the decrease of GFR in patients with mild form within the limits of CKD 1-2 (p=0,013, W-test). No significant changes in GFR were noted during medical management and monitoring. Summary, the cardio-renal syndrome (CKD of any stage and cardiovascular pathology) was revealed in 26 % of patients. Arterial hypertension was registered in 40 %. Conclusions : We found a high frequency of renal function impairment in patients with PHPT, including patients with a mild form of the disease. We did not observe any significant improvement in renal filtration function, after surgical treatment and remission of PHPT. The safety of conservative tactics has been confirmed. The high frequency of cardiovascular pathology in patients with PHPT is beyond doubt and requires prospective studies in the larger cohorts of patients.