Ultrasound transmission time: an in vivo guide to nail thickness

Human fingernail thickness was measured distally in 39 subjects using an adapted electronic micrometer and ultrasound transmission time was measured both distally and proximally. Distal ultrasound nail transmission time correlated well with micrometer measurements. There was a clear rank order of distal and proximal nail transmission times: thumb greater than index greater than middle greater than ring greater than little fingers. Male nails had greater transmission times than female nails on the ring and little fingers. Distal nail transmission time was 8.8% less than proximal transmission time.