Reference chart for relative weight change to detect hypernatraemic dehydration.
OBJECTIVE
The validity of the rule of thumb that infants may have a weight loss of 10% in the first days after birth is unknown. We assessed the validity of this and other rules to detect breast-fed infants with hypernatraemic dehydration.


METHODS
A reference chart for relative weight change was constructed by the LMS method. The reference group was obtained by a retrospective cohort study.


METHODS
1544 healthy, exclusively breast-fed infants with 3075 weight measurements born in the Netherlands and 83 cases of breast-fed infants with hypernatraemic dehydration obtained from literature.


RESULTS
The rule of thumb had a sensitivity of 90.4%, a specificity of 98.3% and a positive predictive value of 3.7%. Referring infants if their weight change is below -2.5 SDS (0.6th centile) in the reference chart in the first week of life and using the rule of thumb in the second week had a sensitivity of 85.5%, a specificity of 99.4% and a positive predictive value of 9.2%.


CONCLUSIONS
The rule of thumb is likely to produce too many false positive results, assuming that for screening purposes the specificity needs to be high. A chart for relative weight change can be helpful to detect infants with hypernatraemic dehydration.
van Dommelen
Paula
P
TNO Quality of Life, Leiden, The Netherlands. P.vanDommelen@pg.tno.nl
van Wouwe
Jacobus P
JP
Breuning-Boers
Jacqueline M
JM
van Buuren
Stef
S
Verkerk
Paul H
PH
D001942:Breast Feeding; D003681:Dehydration / Q000175:diagnosis* / Q000453:epidemiology; D004812:Epidemiologic Methods; D019317:Evidence-Based Medicine; D005260:Female; D006801:Humans; D006955:Hypernatremia / Q000175:diagnosis* / Q000453:epidemiology; D007224:Infant Care / Q000379:methods*; D007231:Infant, Newborn; D008297:Male; D009426:Netherlands / Q000453:epidemiology; D012016:Reference Values; D012017:Referral and Consultation; D015431:Weight Loss