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.
BUN stands for blood urea nitrogen and is the primary end product of protein metabolism. High levels indicate kidney failure or disease, dehydration, shock, high protein diet, certain toxin ingestions, poor circulation to the kidneys and urinary obstruction. Low levels indicate liver disease or starvation.