Childhood age classes, Tissue Volumes and Other Helpful Facts and Numbers

Neonate

0-28 days

Chronic Kidney Disease

GFR <60mL/min/1.73 sqm OR evidence of injury (haematuria or proteinuria)

Surface area of the Small Intestine

Size of a tennis court (250 sqm); 7 metres long

Small Intestine pH

6-7.5 from duodenum to ileum

Plasma Volume

3 L

Blood Volume

7 L

Extracellular water volume

15 L

Intracellular water volume

27 L

Total body water volume

42 L

Infant

>28 days - 12 months

Tissue sequestration volume of distribution

>70 L

Toddler

12-23 months

Preschool Child

2-5 years

School age child

6-11 years

Adolescent

12-17 years

Nephron proximal tubule absorption

100% of filtered glucose and amino acids/proteins, 70% of filtered water and ions (Cl, Na, K, HCO3)

Nephron descending Loop of Henle reabsorption

Water only

(*no solutes reabsorbed*)

Nephron ascending Loop of Henle reabsorption

Solutes (Na, K, Cl, Ca, Mg) only (*no water reabsorbed!*)

Nephron distal tubule and collecting duct reabsorption

Solutes (ions) and water reabsorption

Water reabsorption is regulated by ADH (vasopressin) and aldosterone

Glomerular Filtration Rate in a healthy young adult

120 mL/min

Average GFR of a healthy elderly person 60+ years

75-85 mL/min

CrCl in moderate kidney impairment

< 50-60 mL/min

CrCl in severe kidney impairment

< 30 mL/min

Urine pH range

pH 5-8

Ideal Body Weight

Adjusted Ideal Body Weight