Otherwise, if furnace flue is being abandoned because no longer needed, I would require the top be removed and replaced with a domed galvanized metal cap to keep insects and maybe rodents from taking up residence or using it as a nut cache - cost probably about $50-75 additional.
The creatinine levels in both urine and blood are determined and compared. Normal creatinine clearance for healthy women is 88-128 mL/min. and 97 to 137 mL/min. in males (normal levels may vary slightly between labs). Blood urea nitrogen (BUN) level is another indicator of kidney function.
Creatinine is a metabolic by-product of muscle metabolism, and normally appears in urine in relatively constant quantities over a 24 hour period with normal liquid intake. Therefore, urine creatinine can be used as an indicator of urine water content or as a marker identifying a specimen as urine. Greater than normal intake of water will increase the urine water content (lowering the creatinine level) consequently diluting the amount of drug in urine.