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 is found dissolved in blood and is excreted by the renal tubules. In addition, a small amount of urea is also excreted in sweat. Therefore, the BUN level may reflect functioning of the liver and/or kidneys. In the United States, blood urea nitrogen (BUN) is measured in mg/dL.To convert BUN to a concentration in mmol/L (SI units), multiply by 0.357 ([10 dL/1 L]/[28 mg of N/mmol of urea] = 0.357).n addition, a small amount of urea is also excreted in sweat. Therefore, the BUN level may reflect functioning of the liver and/or kidneys. The reference range of the BUN level is 3-20 mg/dL. Individual laboratories may have different reference ranges, since the procedure may vary.