Decline in Kidney funtion

Hi,
I have an appointment to see a Kidney Specialist.  I phoned-up to see what exactly the appointment is for, and they said it's just for a 'talk.'  They said over the past couple of years, I have had a decline in kidney function.
What does that mean?  Is it necessarily a bad thing?
I did have some blood tests recently and they noted raised creatinine levels, but I don't really know what that means.

Can anyone shed some light on this so I have a bit of an idea of what's going on before I see the Doctor?
I was asked to bring a urine sample and any medications I'm on.  I'm on 'simvastatins' and 'atenonols' to high cholesterol and high blood pressure.
I'm a 31 year old white male.
Thank you.

[doubleaaaron]

Well they just want to talk with you and discuss what may be going on. Your creatinine Is the waste in your blood the more there is the less your kidneys are doing their job of filtering it out. I can't tell you if it is serious or not but one thing is for sure anytime your kidney function declines you should have it checked. But that doesn't always mean that you are in trouble, there are a lot of factors.

[Dr Santos]

How are you? The kidneys perform many vital functions, including removing metabolic waste products from the bloodstream, regulating the body's water balance, and maintaining the pH of the body's fluids. Just like doubleaaron said, creatinine  is a waste product of muscle metabolism  and is removed by the body through the kidneys into the urine. Creatinine has been found to be a fairly reliable indicator of kidney function. As the kidneys become impaired the creatinine level in the blood will rise.

Some drugs affect the creatinine levels in the blood that is why the doctors would want to know what you are taking. There are a variety of urine tests that assess kidney function.Urinalysis is one simple test, however, if results indicate a possibility of impaired kidney function, one or more of the following additional tests is usually performed:  creatinine clearance test, urea clearance test, urine osmolality test, or urine protein test.

I hope this helps. Take care and keep us posted.