Viteri and Alvarado developed the creatinine height index to compare a child's measured urine creatinine excretion relative to that expected based on body height.
Patient selection: child
creatinine height index =
= (actual 24 hour urine creatinine excretion for the child) / (24 hour creatinine excretion of a normal child with same height)
actual urine creatinine excretion in mg per 24 hours =
= (24 hour urine volume in mL) / 100 * (urine creatinine in mg per dL)
expected urine creatinine excretion in mg per 24 hours =
= 252 - (8.01 * (height in cm)) + (0.0817 * ((height in cm)^2))
where:
• According to Tietz (Clinical Guide to Laboratory Tests, Third Edition, page 188), the reference range for a child's urine creatinine excretion should be 8-22 mg per kg per day.
• The 24 hour urine creatinine for normal children from 0 months to 8 years of age are given n Table I, page 697 in Viteria and Alvarado (1970)
ratio of actual to expected urine creatinine excretion =
= (actual urine creatinine excretion) / (predicted urine creatinine excretion)
Interpretation:
• A normal child should have a ratio close to 1.
• A malnourished child with protein deficiency would have a significantly reduced ratio. With protein repletion the ratio should increase towards 1.
Limitations:
• As with any 24 hour urine study, a complete 24 hour urine collection is required for an accurate result.
• Using the urine creatinine as a measure of protein malnutrition assumes normal renal function.
