Section 4 Creatinine-1.PDF

Creatinine section 4  Do you remember tests of renal function? ◼ Glomerular filtration rate=GFR ◼ Urine protein ◼ Plasma creatinine= Pcr ◼ Urine glucose ◼ Plasma urea-Purea ◼ Hematuria ◼ Urine urea- Uurea ◼ Osmolality ◼ Urine volume= V ◼ Cystatin...

Creatinine section 4  Do you remember tests of renal function? ◼ Glomerular filtration rate=GFR ◼ Urine protein ◼ Plasma creatinine= Pcr ◼ Urine glucose ◼ Plasma urea-Purea ◼ Hematuria ◼ Urine urea- Uurea ◼ Osmolality ◼ Urine volume= V ◼ Cystatin C in plasma  Tests of Glomerular Filtration Rate (GFR) ◼ Volume of blood filtered across glomerulus per unit time ◼ Best single measure of kidney function Including: ◼ Urea ◼ Creatinine ◼ Creatinine Clearance ◼ Cystatin C  Creatine Creatine (methyl guanido acetic acid) CH2 – COOH Creatine Is a nitrogenous organic acid. l CH3 – N l Its main role: HN = C – NH2 1. Facilitate recycling of adenosine triphosphate (ATP), the energy currency of the cell, primarily in muscle and brain tissue 2. Creatine also acts as a pH buffer in tissues 3. Present in blood, urine and muscles 4. Present in muscle in creatine phosphate form for energy storage 5. Is synthesized from 3 amino acids: Arginine (basic) Glycine (neutral) Methionine (sulfur) 6. Creatine normal blood level = 0.2 : 0.6 mg/dl 7. Normally there is no creatine in urine  Creatinine Creatinine is considered a NPN compound (nitrogenous compounds, which are not precipitated by protein precipitating reagents). Creatinine is a chemical waste molecule that is generated from muscle metabolism. Approximately 2% of the body's creatine is converted to creatinine every day. Creatinine is transported through the blood stream to the kidneys. The kidneys filter out most of the creatinine and dispose of it in the urine.  Creatinine production Creatine phosphate Creatine phosphokinase Creatine (methyl guanido acetic acid) (liver, brain, muscle) Slow Rapid Non enzymatic (spontaneous) H2O Pi Creatinine Excreted in urine Creatinine normal blood level = 0.8 -1.2 mg/dl. Creatinine normal urine level = 0.5-1.2 mg/dl (24 hr.). “depending on muscle mass” Increase Decrease ◼ Male ◼ Age ◼ Meat in diet ◼ Female ◼ Malnutrition ◼ Muscular body type ◼ Muscle wasting ◼ Cimetidine & some other ◼ Amputation medications  Creatinine Clearance ❑ The best test to show the efficiency of kidney (Why?!) 1. Show the kidney function for last 24 hour 2. Combine between creatinine levels in blood (serum) and in urine for last 24 hour ❑ Normal creatinine clearance is 88 – 128 ml/min for healthy women. ❑ Normal creatinine clearance is 97 – 137 ml/min for healthy men.  [Cr ]urine  Tv CrCl = [Cr ]serumX 60 X 24 ◼ This ratio is decreased in: 1. Narrow kidney artery 2. Hypotension 3. Depletion of water  EXAMPLE (female specimen): If you know that: 1. UCr = 72 mg/dl 2. SCr = 2.0 mg/dl 3. V = 2 liters(2000ml) 4. Time = 24 hours Calculate CrCl value and write your recommendation if this woman may has a problem with her kidney or not. 72 mg/dl  2000 ml / day CrCl = = 50 ml / min 2.0 mg/dl  24 hrs / day  60 min/ hour