Physiological changes in kidneys during pregnancy; [Физиологическая адаптация почек к беременности]

Pregnancy is a unique condition, with the onset of which the woman's body undergoes various adaptive changes aimed primarily at ensuring proper perfusion of the placenta, which is necessary for a successful pregnancy. The kidneys and cardiovascular system play a key role in the physiological adaptation to pregnancy. Already in the early stages of gestation, the changed in the hormonal background contributes to systemic vasodilation, an increase in circulating blood volume, followed by an increase in renal plasma flow and glomerular filtration rate (GFR). Vasodilation contributes to the activation of the renin-angiotensin-aldosterone system, which leads to sodium retention in the body and an increase of plasma volume. Hypervolemia and an increase in GFR cause a decrease in serum creatinine concentration, which today can be considered a favorable sign of obstetric and renal outcomes. Thus, the normal serum creatinine level in a healthy pregnant woman is always lower than the initial, pregestational one. Glomerular hyperfiltration is so pronounced that the urinary excretion of certain substances exceeds the maximum reabsorption capacity of the proximal tubules, and this leads to the appearance of protein and sometimes glucose in the urine. Hyperfiltration, along with changes in fluid and electrolyte balance, is an integral part of the physiological changes that characterize a healthy pregnancy. Although they are aimed at improving gestational outcomes, they can also be the subject of diagnostic errors if the physician is not aware of the physiology of pregnant women. An increase in the average age of women entering their first pregnancy increases the risk of developing extragenital diseases by the time of conception, including kidney disease, which can affect the characteristics of the adaptation process, which, in turn, can also become a source of diagnostic errors. Nephrologists and obstetricians-gynecologists need to have a clear understanding of the physiological gestational changes in the urinary system, which will contribute to the timely detection of pathology, determining the prognosis, and developing individual tactics for managing pregnancy. This article briefly describes the main mechanisms of the physiological adaptation of the kidneys to pregnancy, including the concept of the "physiological response of the kidneys to pregnancy". © 2023 JSC Vidal Rus. All rights reserved.