Title: Creatinine Assay Aim: To determine the creatinine clearance of a selected undiluted urine samples by graphical extrapolation from a creatinine curve. Materials and Apparatus: University of the West Indies: Department of Basic Medical Sciences Laboratory Manual: BC35A, Creatinine Assay, pages 6-8, 2012 Changes to the Method: The experiment utilized one undiluted urine samples for concentration determination instead of five aliquots of twenty four hour urine samples.
The urine sample and standard creatinine solutions were analyzed spectrophotometrically approximately five minutes after they were made up instead of using the allotted time interval (minutes) as suggested by the laboratory manual.
Results: Please see attachments. Discussion Creatinine is a chemical waste molecule that is generated from muscle metabolism. It is an anhydride of creatine, the end product of phosphocreatine metabolism; measurements of its rate of urinary excretion are used as diagnostic indicators of kidney function and muscle mass. The experiment utilized serum creatinine.
Creatinine is filtered out of the blood by the kidneys (glomerular filtration). There is little tubular reabsorption of creatinine. If the filtering of the kidney is deficient, creatinine blood levels rise. Therefore, creatinine levels in blood and urine may be used to calculate the creatinine clearance which reflects the glomerular filtration rate (GFR). The GFR is clinically important because it is a measurement of renal function . A more complete estimation of renal function can be made when interpreting the blood (plasma) concentration of creatinine along with that of urea.
BUN-to-creatinine ratio (the ratio of blood urea nitrogen to creatinine) can indicate other problems besides those intrinsic to the kidney; for example, a urea level raised out of proportion to the creatinine may indicate a pre-renal problem such as volume depletion. The typical human reference ranges for serum creatinine are 0. 5 to 1. 0 mg/dl (about 45-90 ? mol/l) for women and 0. 7 to 1. 2 mg/dl (60-110 ? mol/L) for men. While a baseline serum creatinine of 2. 0 mg/dl (150 ? mol/l) may indicate normal kidney function in a male body builder.
The experimental creatinine levels obtained for the undiluted sample of creatinine is ____________, the values obtained are significantly higher than the normal creatinine values for a healthy male or female. Factors that may contribute to the elevated levels of serum creatinine may include; a disorder of the kidneys and impaired renal function. These disorders include glomerulonephritis characterized by inflammation of the blood vessels in the kidneys, bacterial infection of the kidneys or pyelonephritis and acute tubular necrosis, or cell death in the kidneys’ small tubes caused by toxic substances.
Obstruction of the urinary tract, such as with prostate disease or kidney stones, can also cause impaired kidney function and lead to elevated creatinine levels. Increased muscle mass indicates increased creatine phosphate, which translates to increased creatinine levels in the blood. Acromegaly and gigantism are disorders caused by abnormality of the pituitary gland and can be associated with increased muscle mass also the ingestion of steroidal substances that stimulates an increase in muscle mass.
When medical conditions affect normal blood flow to the kidneys, renal function becomes impaired thus increasing creatinine levels in the blood. Shock, or a sudden critical drop in blood flow to the body, compromises renal status because the kidneys are not being nourished. Dehydration causes reduced renal blood flow, as well. In people with congestive heart failure, the heart is not adequately pumping blood towards the kidneys and other organs. Atherosclerosis, or narrowing of the arteries, and diabetic nephropathy are other conditions that reduce blood flow to the kidneys.
Precautions/Sources of Error: 1. The experiment utilize spectrophotometric machines that are susceptible to light interfence from the external environment and interference from glassware that is not properly cleaned, this may cause inaccurate readings. 2. Contamination of serum standard solutions of creatinine may give inaccurate readings when using the spectrophotometric machines, hence contamination should be prevented by using clean glassware and wearing all the protected clothing that is applicable. Questions a) Factors that may contribute to varying creatinine levels include: (1)The most common abnormality in a creatinine blood level is a change in kidney function. The kidneys are composed of around a million filters for each kidney, called nephrons. Each of these nephrons contains tubular structures that accomplish the filtering of waste materials and the re-absorption of necessary materials in the blood that passed through the nephrons. Most creatinine is normally filtered out along two structures called the glomerulus and proximal convoluted tubule, maintaining the low levels of creatinine in the blood.
A rise in creatinine blood levels indicates that this filtration is not taking place, suggesting there is a problem with kidney function. (2) Creatinine levels can be affected by transient or non-disease factors that are not kidney malfunction. Bodybuilders, because of the excess of muscular tissue that creates creatinine, will typically have high levels of creatinine. Severe dehydration will cause higher than normal creatinine. Eating a great deal of meat just hours before blood is drawn can elevate creatinine levels.
Some drugs will cause higher than normal creatinine blood levels. These causes are ruled out before a follow up test to determine the cause of elevated creatinine. Low creatinine levels may indicate muscular dystrophy or myasthenia gravis. (3) Preeclampsia is a condition during pregnancy, the cause of which is poorly understood. Elevated creatinine may indicate preeclampsia in pregnant women, especially women on their first pregnancy. Untreated preeclampsia can lead to eclampsia, a life-threatening seizure disorder.
Elevated creatinine in conjunction with swelling of the hands and face is an early sign of preeclampsia. Later signs may include persistent headache, pain in the upper-right quadrant of the abdomen, inadequate urination, agitation and nausea. 2b) The amount of creatinine the body produces each day depends on the person’s muscle mass: a young, muscular man produces more creatinine than a average non athletic male. Because muscle mass normally changes very little, creatinine is usually produced at about the same rate every day in each person.
However, if continuous exercise is performed as in the case of an athlete the muscle employs the creatine phosphate metabolism more often and hence more creatine and creatinine is metabolized which will eventually increase the muscle mass of the individual. Athletes may also ingest creatine which will stimulate the production of creatinine in the body and will contribute to an increase in muscle mass. 2c) The blood urea test is a measure of the amount of nitrogen in the blood in the form of urea, and a measurement of renal function.
Urea is a by-product from metabolism of proteins by the liver and is removed from the blood by the kidneys. The liver produces urea in the urea cycle as a waste product of the digestion of protein. Normal human adult blood should contain between 7 to 21 mg of urea nitrogen per 100 ml (7–21 mg/dL) of blood. BUN is an indication of renal health. Normal ranges 2. 5-6. 5mmol/L. If Glomerular Filtration Rate (GFR) and blood volume then BUN will increase. Conclusion The experimental results indicate that there was a elevated serum creatinine level that was above the normal levels.
Elevated serum concentration may indicate impaired liver function. The serum creatinine level was found to be ______________. References 1. Delanghe J; De Slypere JP, De Buyzere M, Robbrecht J, Wieme R, Vermeulen A (Aug 1989). “Normal reference values for creatine, creatinine, and carnitine are lower in vegetarians”. Retreived October 3, 2012. 2. “The creatine-creatinine equilibrium. The apparent dissociation constants of creatine and creatinine. Retrieved October 3, 2012. 3. “International Society of Sports Nutrition position stand: creatine supplementation and exercise”. October 3, 2012.