Chapter 5 - Sodium Physiology

Question 1

most abundant ion is ECF

Answer 1

Sodium

Question 2

Normal serum sodium concentration

Answer 2

135-145 mEq/l

Question 3

daily sodium requirement

Answer 3

in children - 2-3mEq/kg body weight

Adult – 1.5mEq/kg/day

Question 4

Formula to calculate fraction of excretion of Na

Answer 4

FENa% = (urine Na/ Serum Na) / ( Urine Cr/serum Cr) x 100

Question 5

FENa interpretation

Answer 5

• FENa helps to differentiate acute tubular necrosis from pre renal state
• FENa >2% –>ATN
• FENa <1% –> Pre renal state ( eg: dehydration etc)
  FENa 1-2% –> maybe seen in both