Reserva funcional renal. Concepto y aplicabilidad potencial en la práctica clínica

Abstract

Renal functional reserve. Concept and potential application in clinical practice Renal functional reserve (RFR) is the capacity of the kidney to increase its glomerular filtration rate (GFR) in response to physiological or pathological stimuli. The most commonly used stimuli to assess this reserve are an oral load of proteins of animal origin, amino acid infusions, dopamine, glucagon or combinations of them. RFR is calculated as the difference between stimulated and baseline GFR. Vegetarians have lower baseline GFR than the general population and an increased RFR. Subjects with only one kidney and those suffering from chronic nephropathies usually have a reduced or absent RFR despite having normal basal GFR. Quantification of RFR may be useful to detect subclinical renal damage, physiological conditions that reduce baseline GFR, evaluation of potential donors for kidney transplantation, suspected hyperfiltration, detection of renal lability against acute injuries or pregnancy and the evaluation after an acute renal injury when renal function seems to be recovered and residual subclinical damage is suspected.

Estimativa da taxa de filtração glomerular na prática clínica: posicionamento consensual da Sociedade Brasileira de Nefrologia (SBN) e Sociedade Brasileira de Patologia Clínica e Medicina Laboratorial (SBPC/ML)

“…Outro conceito importante é a reserva funcional renal, caracterizada como a capacidade dos rins em aumentar a TFG em resposta a estímulos fisiológicos ou patológicos 23 . O estímulo conhecido e mais comum que estimula essa reserva, aumentando a TFG, é a sobrecarga de proteínas.…”

“…A reserva funcional renal é calculada pela diferença entre a TFG estimulada (aumentada pelo estímulo) e a TFG basal. Alguns exemplos práticos são descritos a seguir: indivíduos vegetarianos têm TFG basal menor que a da população geral e maior reserva funcional renal; pacientes com nefropatias crônicas e rim único usualmente têm reserva funcional renal reduzida ou ausente, mesmo se tiverem TFG normal 23 .…”

Estimated glomerular filtration rate in clinical practice: Consensus positioning of the Brazilian Society of Nephrology (SBN) and Brazilian Society of Clinical Pathology and Laboratory Medicine (SBPC/ML)

“…Another important concept is renal functional reserve, characterized as the capacity of the kidneys to increase GFR in response to physiological or pathological stimuli 23 . The best-known and most common stimulus that boosts this reserve, increasing GFR, is protein overload.…”

“…Renal functional reserve is calculated by the difference between stimulated GFR (increased by the stimulus) and baseline GFR. Some practical examples are described as follows: vegetarian individuals have a lower baseline GFR compared to the general population, and higher renal functional reserve; patients with chronic nephropathies and a solitary kidney usually have reduced or absent renal functional reserve, even if they have normal GFR 23 .…”

Evaluación de la recolección de orina de 24 horas a partir de la creatininuria: fórmulas para estimarla y su rendimiento

“…Influyen en forma importante la ingesta de proteínas y el ejercicio, que la aumentan 1,3 . La ingesta de carne de res y de pescado, que contienen creatinina, se suma a la creatinina endógena y aumenta su excreción renal 4,8,14 .…”