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.
Urea in high concentrations can cause oxidative stress in cells (R, R2). However, high BUN is also an indicator of other underlying conditions. High BUN indicates increased protein breakdown, which is associated with decreased immune function. A study shows that patients with elevated BUN (> 20 mg/dl) have an increased risk of infection .