(Birth – 36 Months) • Head Occipital-frontal Circumference Percentile (Birth - 36 Months)

[Khurram Shahzad]

One question so far which is regarding Vital “Occipital-frontal Head Circumference Percentile (Birth - 36 months) ”

 

Data we get from following link

 

 

LMS :

https://www.cdc.gov/growthcharts/percentile_data_files.htm

1. HCAGEINF Cdc-excel[XLS – 34 KB]  HCAGEINF Cdc-excel[CSV – 12 KB]    
   Head circumference-for-age charts, birth to 36 months, LMS parameters and selected smoothed head circumference percentiles in centimeters, by sex and age

 

Z Score:

 

https://www.cdc.gov/growthcharts/zscore.htm

1. ZHCAGEINF Cdc-excel[XLS – 42 KB] ZHCAGEINF Cdc-excel[CSV – 17 KB]    
   Head circumference-for-age charts, birth to 36 months, selected head circumference z-scores in centimeters, by sex and age

The Formula to calculate is following:

 

Z-score = ((Headcircumference/M)L - 1) / (L * S)

 

 

The case is following

 

Patient age 27 months

Head Circumference is 13.5

 

Z Score = -8.70

Expect value as per following link is 0.1%

https://reference.medscape.com/calculator/673/cdc-nchs-infant-head-circumference-for-age-percentiles-lt-36-months

 

 

But our z score is this -16.27791, which look wrong because value range is between 3.00 to -3.00.