The role of dehydration in the development of acute kidney injury in patients with COVID-19

Background. Acute kidney injury often complicates the course of COVID-19; in many patients it develops even before hospitalization, and the reasons for its development are not sufficiently clear.

Aim. To study the role of dehydration in the development of community-onset acute kidney injury in COVID-19.

Material and methods. 329 patients with COVID-19 were examined (age 58.0±14.3 years, 172 men, 157 women). Acute kidney injury was diagnosed according to the Russian recommendations of 2020. To determine prerenal acute kidney injury, the ratio of blood urea nitrogen to blood creatinine was calculated, and to diagnose dehydration — the calculated osmolarity of blood serum. Data are presented for a normal distribution as the arithmetic mean and standard deviation (M±SD), for a non-normal distribution — as a median (Me) and interquartile range (IQR). Univariate and multivariate logistic regression analyzes were used. To assess the diagnostic significance of quantitative characteristics in predicting a certain outcome, the ROC curve analysis method was used. Differences were considered statistically significant at p <0.05.

Results. Acute kidney injury was diagnosed in 70 (21.3%) patients, of which 58 (82.9%) were community-acquired. In 16 (27.6%) patients with community-onset acute kidney injury, it was of a prerenal nature, of which in 13 (81.3%) the calculated serum osmolarity exceeded 295 mOsm/L. Independent factors directly associated with prerenal prehospital acute kidney injury were estimated serum osmolarity (p <0.001), C-reactive protein level (p <0.001) and age (p=0.003) (R2=0.23, F=33,34).

Conclusion. Acute kidney injury complicates the course of COVID-19, and in most patients, it develops even at the prehospital stage. Estimated serum osmolarity is directly and independently associated with prerenal community-onset acute kidney injury, suggesting the important role of dehydration in its development.