Plasma creatinine levels in preterm infants

Preterm infants are well known to be at increased risk of acute renal failure as well as transient fluid and electrolyte disturbances particularly in the first few days of life.The etiology of neonatal acute renal failure is most often associated with hemodynamic disturbances such as hypotension, hypovolemia, and exposure to acute asphyxia.Plasma creatinine concentration reflects the balance between production from creatine stores in muscle and clearance by glomerular filtration. Because preterm infants have a small muscle mass, it would be expected that plasma creatinine concentration would be low if renal clearance was normal. In steady states in adults, muscle mass is constant, and creatinine is not reabsorbed by the renal tubule; therefore, creatinine concentration provides a proxy measure of GFR. Formulae have been derived to calculate GFR from plasma creatinine concentration although they are not valid in the early neonatal period when GFR is changing rapidly.