IGF-1 Optimal Reference Ranges

Written by Tommy Wood MD, PhD

June 11, 2017

We know that the normal range your laboratory gives you for a specific blood marker doesn’t necessarily imply what’s truly optimal. Based on this paper showing the U-shaped curve of IGF-1 levels and mortality, and age-specific IGF-1 “normal” ranges from the Mayo Clinic laboratories, I have created something close to an “optimal” range for IGF-1 (see table below). I did this by taking the average (mean) of the normal range, then including just ½ of a standard deviation either side. This will cover the 38% of people either side of average, and captures the region where the error margin suggests a measured IGF-1 level is associated with the lowest mortality rate. As the truly lowest mortality rate is in those with the 55th percentile of IGF-1 level (i.e. just above average), being in the upper half of our optimal range may be a bit better. However, if you’re worrying intensely about your IGF-1 level and it’s within the range below, we think there are probably other things you can optimise that will be more impactful. Like closing the computer and going for a walk.

  Estimated optimal range (ng/ml)
Males (Age) Mean Minimum Maximum
18-22 267 223 310
23-25 206 171 241
26-30 195 161 228
31-35 182 150 214
36-40 170 140 201
41-45 160 131 188
46-50 150 122 177
51-55 141 115 167
56-60 133 108 158
61-65 127 103 150
66-70 121 98 143
71-75 116 95 137
76-80 113 93 132
81-85 109 90 128
86-90 106 88 124
>91 103 85 120
       
Females (Age)      
18-22 228 192 263
23-25 197 166 227
26-30 185 155 214
31-35 169 142 197
36-40 156 131 182
41-45 145 121 168
46-50 136 113 158
51-55 129 106 151
56-60 123 101 144
61-65 118 97 139
66-70 114 94 134
71-75 111 91 130
76-80 108 90 127
81-85 106 88 123
86-90 104 86 122
>91 102 83 121

 

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