Investigating the Relationship between Serum Phosphorus Level and Related Factors with Kidney Dysfunction in Chronic Kidney Patients

Chronic kidney disease or CKD is defined as functional failure or structural abnormality of the kidney. Diabetes and high blood pressure are the primary causes of this illness. Because the underlying causes of chronic kidney disease are more common now, the disease's financial burden on health systems around the globe has gone up. This disease can cause a wide range of complications, including changes in electrolytes and other known indicators in the blood. One of the less investigated indicators is the serum level of phosphorus in these patients. Therefore, we designed and implemented a study to investigate the relationship between serum phosphorus levels and kidney dysfunction in chronic kidney patients.

This study was a descriptive and retrospective study that was conducted on 110 patients with chronic kidney disease admitted to Imam Khomeini Teaching Hospital in Sari. The census sampling method and data collection tool was a checklist. Phosphorus values ​​obtained by blood tests and recorded in patients' files were studied. The comparison between the grouped variables was done with the chi-score test and Fisher's exact test. Quantitative variables were compared between 2 groups with a t-test and in more than 2 groups with an analysis of variance or their non-parametric equivalent. Also, the correlation between serum phosphorus level and GFR was done with Pearson or Spearman correlation coefficient. Partial Correlation was used to adjust the effect of confounding variables. Also, the normality of quantitative variables was evaluated with Shapiro-Wilks and based on skewness and kurtosis indices. Data analysis was done with SPSS software version 25

Of the 110 individuals that were examined, 51 (46.4%) were female and 59 (53.6%) were male. Of the 110 individuals, 95.5%, or 105 patients, had underlying medical conditions. During their time in the hospital, 21 patients (19.1%) were admitted to the intensive care unit. 19 individuals were in the G3 stage, 41 in the G4 stage, and 50 were in the G5 stage of CKD. Also, 69 patients were diagnosed with diabetes. Of these, 13 patients were in the G3 stage, 28 patients were in the G4 stage, and 28 patients were in the G5 stage of chronic kidney disease. The average level of blood urea and creatinine was reported to be 125.0255 mmol/L and 4.2975 mg/dL, respectively. Also, the calcium serum level was 8.9109 mg/dL and the phosphorus serum level was 4.6873 mg/dL. Also, the average eGFR among 110 evaluated patients was 19.2345 mL/min/1.73m^2. Serum phosphorus levels and eGFR in men are correlated, and this link is significant (P=0.000). However, the P-value of 0.087 indicates that there is no significant association between eGFR and blood phosphorus levels in women. This connection was significant in hypertensive individuals (P=0.003). Furthermore, in contrast to systolic blood pressure, there is a substantial correlation between patients' diastolic blood pressure and eGFR.

Phosphorus serum level plays a role in determining the severity and prognosis of chronic kidney disease. Also, there is a direct relationship between diastolic blood pressure and the severity of this disease.