PHOSPHARIC-CALCIUM METABOLISM IN PATIENTS UNDER PROGRAM HEMODIALYSIS

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Relevance. The number of patients who suffer from stage 5 chronic kidney disease and therefore require permanent treatment on program hemodialysis is currently more than two million people worldwide [1, 2]. However, these are only those few who are lucky enough to have constant access to high-tech equipment and specialist assistance: this is only 10% of people who need hemodialysis [3]. Violation of phosphorus-calcium metabolism is a common pathology in patients on program hemodialysis [2, 4]. The effect of blood flow velocity to maintain optimal levels of calcium (Ca), phosphorus (P) and the ratio of calcium and phosphorus (Ca x P) in serum in patients with PGD has not been studied.

The purpose of the study was to determine the relationship between blood flow velocity and calcium-phosphorus metabolism (phosphorus, calcium, parathyroid hormone, calcium-phosphorus product) in patients undergoing program hemodialysis; determination of the number of patients who have reached the target indicators of calcium-phosphorus metabolism according to KDOQI and KDIGO.

Materials and research methods. A retrospective study of 67 medical records was conducted at the Ural Medical Center LLC from January to March 2022. Patients were included in the study if they had stage 5 CKD, established according to KDIGO, and were undergoing program hemodialysis therapy at least 2 times for 3 hours in the last six months, the age of patients over 18 years, the presence of vascular access through a prosthesis or arteriovenous fistula. The following variables were assessed: demographic data such as age, gender, laboratory parameters (calcium, phosphorus, parathyroid hormone (PTH), phosphorus-calcium product), blood flow velocity (mL/min, SCT). Target values of phosphorus-calcium metabolism according to KDOQI: PTH - 150-300 pg / ml, adjusted total calcium (Ca) - 2.1-2.37 mmol / l, phosphorus (P) - 1.13-1.78 mmol / l [5] ; according to KDIGO: PTH - 130-585 pg / ml, adjusted total calcium (Ca) - 2.1-2.6 mmol / l, phosphorus (P) - 0.8-1.5 mmol / l [6] .

According to the blood flow velocity, the patients were divided into 3 groups, in the 1st group 30 patients with STT more than 300 ml/min were distributed, in the 2nd group 30 patients with STT in the range from 300 to 350 ml/min were included, in the 3rd group with minimum SKT less than 300 ml/min were placed 7 patients.

Statistical analysis of the data was carried out using Statistica 13.0. The mean value, standard deviation was calculated, the correlation between blood flow velocity and laboratory parameters was determined using the Pearson method, p<0.05 values were considered statistically significant.

Research results.

The study included 67 patients: 38 women (56.7%) and 29 men (43.3%), mean age 59.5±11.3. Group 1 included 10 women (33.3%), 20 men (66.6%), age 57.8±8 years, group 2 included 23 women (76.6%) and 7 men (23.3% ), age 58.2±13.8 years, in group 3 - 5 women (71.4%), 2 men (28.5%), age - 71.7±9.2 years. MT was 269 ± 27.6 ml/min in group 1, 312 ± 15.9 in group 2, and 372 ± 26.8 ml/min in group 3 (p <0.05).

In all groups, the levels of calcium and phosphorus were within the normal range, while the target levels of PTH were not achieved in any group. The maximum calcium level was in group 2 (2.27 ± 0.14 mmol/l), slightly lower in group 1 (2.22 ± 0.14 mmol/l), and the lowest in group 3 (2.19 ± 0.08 mmol/l) (p<0.001). There were no significant differences in the levels of phosphorus and PTH between the study groups of patients. There was no correlation dependence of SKT with any indicator (p>0.05).

The second goal of our study was to compare the relative number of patients who achieved the target values of indicators of phosphorus-calcium metabolism according to KDOQ. The percentage of patients who achieved the desired level of calcium varied slightly between KDOQI and KDIGO - 76% and 64%, respectively. 67% of patients exceeded the KDIGO phosphorus target, while KDOQI recommendations were met by almost half of the patients - 47%. Similar discrepancies are typical for PTH levels: the majority of patients (65%) exceeded the KDOQI recommendation threshold, and the target value for KDIGO was achieved in 58% of patients. Judging by the results of our study, phosphorus and PTH turned out to be the most difficult indicators to control.

Discussion.

The control of phosphorus-calcium metabolism in patients on hemodialysis is important for maintaining not only the musculoskeletal system, but also cardiovascular pathology. There is a relationship between indicators of phosphorus-calcium metabolism and mortality from any cause in this category of patients [7, 8]. Hyperphosphatemia, in particular, is associated with more pronounced vascular calcification and mortality from cardiovascular diseases: according to Zhang Y et al. with an increase in the level of phosphorus by 0.323 mmol/l, the risk of death increases by 18% [9]. Unfortunately, diet and dialysis clearance do not always allow maintaining calcium-phosphorus balance within the target limits, so the search for other methods continues.

About the authors

Alexandra Alexandrovna Shtanova

Email: alekshtanova@gmail.com
ORCID iD: 0000-0002-8104-0017

5th year student of the medical and preventive faculty

Daria Artemovna Stepina

Email: d.stepina37@gmail.com
ORCID iD: 0000-0001-5365-7792

5th year student of the medical and preventive faculty

Inessa Nikolaevna Kupriyanova

Author for correspondence.
Email: 237380@mail.ru
ORCID iD: 0000-0002-9464-6560

Ph.D., Associate Professor Departments of Faculty Therapy, Endocrinology, Allergology and Immunology

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