Filter paper collection of plasma for IGF-I test in patients with acromegaly.

The concentration of insulin-like growth factor I (IGF-I) was determined in paired specimens of liquid plasma and of plasma that had been applied to a filter paper disk, dried, and eluted; the measurements were performed by an immunochemiluminometric assay (ICMA). The 129 paired assays showed good correlation: y = 1.04x + 4.99; R2 = 0.934, where y is the result on dried samples and x is that on liquid samples. In 18 patients with acromegaly who lived on an island off the West Pacific Rim, plasma specimens were collected, applied to filter paper, dried, and mailed to a laboratory in the Upper Midwest of the United States. IGF-I was eluted from the filter paper disks and measured by ICMA. IGF-I concentrations ranged from 101 to 254 ng/ml in 11 patients with newly diagnosed but untreated acromegaly, 138 to 503 ng/ml in 4 patients with recurrent acromegaly, and 27 to 88 ng/ml in 3 patients with surgically cured acromegaly. These data demonstrate that plasma specimens of patients with acromegaly can be collected on filter paper disks and mailed to a laboratory on a distant continent for measurement of IGF-I. Such use of laboratory resources in one continent to help another continent, "Laboratories Without Borders," is somewhat analogous to the program "Doctors Without Borders."