Assessment of Volume Status in Chronic Kidney Disease

Abstract

Overhydration and dehydration remain a difficult balance to maintain for children with chronic kidney disease (CKD). For clinicians managing children with CKD, especially those on dialysis, an accurate assessment of volume continues to be one of the most difficult issues and one that needs regular evaluation to maintain optimal sodium and water homeostasis. Traditional tools including clinical history, physical examination, and measurement of blood pressure may not provide an accurate assessment of fluid overload, which remains one of the main drivers of arterial hypertension in children with CKD and those receiving kidney replacement therapy (KRT). Various techniques have been proposed to assess volume accurately in these patients including singleand multifrequency bioimpedance analysis and, for children on hemodialysis (HD), blood volume monitoring. Both have gained much attention over the past few years, while limited experience and scarce data are available for lung ultrasound, inferior vena cava echography and use of N-terminal pro-brain natriuretic peptide in children with severe CKD and those requiring dialysis. For the clinician, it remains important to remember that patients often have a combination of etiologies (e.g., volume overload and increased renin). A detailed clinical history and examination, supported by serial measurements using one or more of the above techniques of volume assessment, can guide management and maintain the child in an euvolemic state, avoiding the deleterious effect of fluid excess or depletion. Currently, no single technique can be considered as gold standard, but each method, at best, contributes to improving volume assessmentwhen repeated over time on the same patient.