QUESTION:   Bloodwork consistently shows that my "creatinine" level is high. Nurses and doctors advise me to drink more water, but lots of water has no effect. Any advice?

ANSWER:   What you're describing is one of several markers doctors use to figure out how well your kidneys are working.

The serum BUN (blood urea nitrogen) level is another important blood level that goes hand in hand with a blood creatinine level. It would be helpful to know your BUN level, too. Blood urea nitrogen and creatinine are just breakdown products of blood and muscle, respectively. In a normal healthy state, there's a fairly steady and predictable breakdown of old red blood cells and muscle so that the amount of BUN and creatinine in the blood remains within a normal range. But if either too much blood or muscle breakdown occurs, or the kidneys can't properly get rid of these waste products, the blood levels of BUN and creatinine will rise.

What's more, in a state of dehydration, the level of BUN rises much faster in proportion to the level of creatinine. An abnormally high BUN-to-creatinine ratio suggests dehydration. The problem with interpreting your rise in serum creatinine is that it could mean several different things. Yes, it could mean that you're dehydrated, but I don't have enough information to be sure.

One very common cause for an unexplained recent rise in creatinine is a side effect from a medication. For example, if you're taking a water pill for blood pressure or fluid retention, that could dehydrate you a bit and make both the BUN and creatinine levels rise. I'd recommend that you review your medication list with your doctor to determine whether some drug is affecting your creatinine level.

If no offending medication is found, I'd see a kidney specialist. A 24-hour urine collection can measure creatinine and protein excretion and determine extent of kidney impairment. Your problem may be acute and reversible, or it might be a chronic decline in kidney function from high blood pressure, diabetes, or kidney disease.

Mild impairment isn't necessarily cause for concern, but it does need to be watched.

Lastly, make sure your doctor isn't giving you any pills that can hurt your kidneys.