This happens about 2-3% of the time in people with celiac disease and can lead to false-negative test results. Common tests for celiac disease include: 1  Anti-tissue transglutaminase antibody (anti-tTG), IgA: detects antibodies to tissue transglutaminase, an enzyme that causes the crosslinking of certain proteins. 2  Anti-tTG, IgA is the most sensitive and specific blood test for celiac disease.
A contour line is a line drawn on a topographic map to indicate ground elevation or depression. A contour interval is the vertical distance or difference in elevation between contour lines. Index contours are bold or thicker lines that appear at every fifth contour line.
Colors may also be used with contour lines. Normally contour lines are identified with the value at each end, or at the top of closed circular systems, as shown in figure 4-15. The change in numerical value between each contour line is called the contour interval..