For this telescope, the lenses are a concave convex (one side curved out and the other curved in) and a plano concave (one flat side and one side curved in). The plano concave lens is used as the eyepiece with the plano (flat) side facing the eye.
If kidney function begins to decline, BUN and creatinine rise. A normal creatinine depends on muscle mass and age. In general, a normal creatine is 0.5 to 1.2 milligrams per deciliter (mg/dL). A normal BUN is 7 to 20 mg/dL.
Quick Answer. Normal levels of blood urea nitrogen, or BUN, for adults and children range from 10 to 20 and 5 to 18 milligrams per deciliter, respectively, according to WebMD. For adult men and women, normal creatinine levels range between 0.7 to 1.3 and 0.6 to 1.1 milligrams per deciliter, respectively, according to Healthline. Keep Learning.