Metabolic Demand, Renal Mass, and Glomerular Filtration Rate Changes in Men and Women: Lessons from Living Kidney Donors and Recipients
Abstract
BACKGROUND: The determinants of glomerular filtration rate (GFR) and its changes over time are multiple and diverse. Nephron endowment is the starting point for GFR. Low renal endowment due to maternal undernutrition or premature birth as well as the loss of renal mass because of surgical procedures have a major impact on GFR. Eventually low renal mass may lead to organ damage when combined with metabolic syndrome and obesity or diabetes. The kidney has a major role in maintaining homeostasis. Changes in metabolic demand have a major influence in renal function. Increments in metabolic demand may determine a compensatory increase in GFR to cope with the new metabolic status. Clear examples of these conditions are pregnancy and obesity. Also, GFR may vary in response to the stimulation of renal reserve and the ageing process. All these aspects are different in men and women and may explain gender differences in renal function in health and disease. SUMMARY: In general, women have lower renal mass and lower metabolic demand. However, the study of these aspects in humans is complex. A living donor has two healthy kidneys and after nephrectomy, one of them remains in the same subject undergoing mechanisms of compensation whereas the other is transplanted in a patient with CKD that might have different body size, sex or age, than the donor. This makes the living kidney donation a unique setting to study the determinants of GFR. In this review, we take advantage of data from living kidney donors and recipients to understand diverse determinants of GFR, focusing on gender differences in renal function. KEY MESSAGES: In health and disease, several factors influence GFR like renal mass, the presence or absence of renal reserve, metabolic demand, the capacity of the kidney to adapt to it and the effect of ageing and senescence. In all of them, gender differences play a relevant role, making differences between men and women a factor to consider in the analysis of GFR.
