Full HTML 09 V1 I3


Dr.Bhupendra Kr.Sharma* and Ms.Priyanka Mishra
Department of Chemistry, Mewar University, Chittorgarh, Rajastshan, India


Kidney is an important organ of the human body. It removes the waste product of the body metabolism and reabsorbs certain things which are required by the body. The function of the kidney is measured by Kidney Function Test(K.F.T).In this test other biochemical wastes of the body like creatinine,uric acid,urea,potassium,chloride and sodium are measured. Excreted creatinine levels can be correlated to the renal function as creatinine is not reabsorbed by kidney. In this study the creatinine levels of both clinically normal and critical ranges are correlated with other renal bio-chemical parameters. Studies indicate that excretion of bio-chemical parameters don’t follow any definitive patter within the normal range of the creatinine clearance, but beyond the critical value other parameters also increase with creatinine.Studies indicate the consideration of the creatinine excretion values are not co-linear with other parameters.

Keywords: Kidney Function Test (K.F.T), creatinine, uric acid, renal function.


The kidney participates in whole-body homeostasis, regulating acid-base balance, electrolyte concentrations, extracellular fluid volume, and blood pressure. The kidney accomplishes these homeostasis functions both independently and in concert with other organs1.

Many of the kidney’s functions are accomplished by relatively simple mechanisms of filtration, reabsorption, and secretion, which take place in the nephron. Filtration, which takes place in renal corpuscle, is the process by which cells and large proteins are filtered from the blood to make an ultra filtrate that eventually becomes urine. The kidney generates 180 liters of filtrate a day, while reabsorbing a large percentage, allowing for the generation of only approximately two liters of urine. Reabsorption is the transport of molecules from this ultra filtrate and into the blood. Secretion is the reverse process, in which molecules are transported in the opposite direction, from the blood into urine 2.

Urinary excretation rate = Filtration rate – Reabsorption rate + Secretion rate1.

Renal failure is mainly determined by a decrease in glomerular filtration rate, the rate at which blood is filtered in the glomerular of the kidney. This is detected by a decrease in or absence of urine production or determination of waste products (creatinine, urea) in the blood 2.

GFR will become important in future to predict functioning of the kidney3. Strangely, there is very little consensus as to what exactly constitutes acute renal failure. In effect, renal function and renal physiological reserve involves the ability to filter and clear unwanted substances, and to reabsorb essential, though filtered, material. Ideally, it will be better to measure the plasma level of a substance that is neither secreted nor reabsorbed by the kidney, measure the urinary concentration and volume, and calculate the clearance of the substance and thus the glomerular filtration rate (GFR). No such substance is readily and inexpensively available. Consequently, physicians have had to “make do” with urea and creatinine4.

Urea is produced as a break down product of protein. It is completely filtered by the kidney, but unfortunately is also reabsorbed. Thus urea clearance grossly underestimates GFR. In addition, the amount of urea reabsorbed increases with dehydration.

Creatinine is a metabolic by product of muscle metabolism (it is derived from creatine and phosphocreatine). For the majority of patients the muscle turnover varies little from day to day, and the serum creatinine is more or less constant. Creatinine is removed from the blood chiefly by the kidneys, primarily by glomerular filtration, but also by proximal tubular secretion. Little or no tubular reabsorption of creatinine occurs. If the filtration in the kidney is deficient, creatinine blood levels rise. Therefore, creatinine levels in blood and urine may be used to calculate the creatinine clearance (CrCl), which correlates with the glomerular filtration rate (GFR). Serum creatinine is probably the most widely used indirect measure of GFR; it is easy and inexpensive to measure. Its importance comes from the fact that it is an easily measured byproduct of muscle metabolism that is excreted unchanged by the kidneys3. Serum creatinine is so highly dependent on age, sex and body size, a number of corrections and formulae have been developed to estimate the muscle mass and assumed creatinine production3.

Kidney Function Test (K.F.T) is a collective terms for a variety of individual tests and procedures that can be done to evaluate how well the kidney are functioning. In Kidney function test (KFT) the level of Urea,Creatinine,Uric acid, Sodium(Na+1),Potassium(K+1),chloride(Cl-1) are determined and Urinalysis is also a part of this test5.

K.F.T test results give quantitative values of different biochemical parameters as pointed above. The present study will endeavor to understand the variation of the different biochemical parameters with that of creatinine. We try to understand the variations of the other parameters like of Urea, Uric acid, Sodium (Na+1), Potassium (K+1), chloride (Cl-1) with creatinine for healthy as well as with creatinine values outside the clinically safe range. The objective is to find whether any predictive pattern of the other bio-chemical parameters exist with that of the cretainine readings.

Material and Methods

Serum analysis data are taken from tests carried out in the Saras Hospital Clinical Pathology Lab, Badarpur, and Faridabad.All the tests were performed as per the standard clinical practice. Though urine analysis is part of K.F.T, we have not taken into account the results. Since our study is limited to only observing the correlation between creatinine release and other Kidney Function Test parameters, we have overlooked the sex, body weights and age of the people whose samples have been analyzed.

Results and Discussion

As stated earlier the objective of the study is to co-relate the different parameters of the KFT and observe their variation with respect creatinine. Also to see if the the rate of glomerular filtration rate (GFR) determines the release of the other products from kidney in addition to creatinine.

In the present study we analyze the data of the seventeen samples. We plot the all the parameters versus the serum creatinine as it is considered to be the indicator of filtration rate of the kidney to analyse and decipher the rate of the release of the other products with respect to the serum creatinine.The other K.F.T parameters are studied as function of  creatinine excreted. The values are plotted with creatinine as the independent variable (Figures 1 to 5). The figures give an interesting correlation between the creatinine excretion and the other parameters like urea, sodium, potassium, chloride and uric acid. The clinically safe range for the ceatinine is 0.6-1.4 mg/dl though it might differ a little bit in males because of the muscle variation6. It can be observed that the in the normal range the release of the parameters are not following any definitive pattern. But, beyond the highest value i.e. at about the when creatinine clearance is indicative of the stage of renal mal-function, the others parameters also are found to   increase almost sharply except for the last sample in whose case the other parameters have declined compared to creatinine.Though there is no linear progress, overall all the parameters have increased with increase in creatinine value.

Figure 1:Chloride(mmol/L) vs Serum Creatinine(mg/dl)

Figure 2:Potassium(mmol/L) vs Serum Creatinine(mg/dl)

Figure 3:Sodium(mmol/L) vs Serum Creatinine(mg/dl)

Figure 4:Uric Acid(mg/dl) vs Serum Creatinine(mg/dl)


Figure 5:Urea(mg/dl) vs Serum Creatinine(mg/dl)


The serum creatinine and other parameters of KFT are not co-related linearly. Hence, excretion of serum creatinine has no bearings on the value of other K.F.T parameters at least within the medically safe range.Secreation of other parameters have been found to increase almost linearly when the creatinine clearance has reached the clinically critical value. Serum creatinine may not be any help in predicting the other K.F.T parameters. We need to expand our study and more data are required for a proper analysis and conclusion regarding the interconnectedness of the filtration, reabsorption and secretion process of kidney. Moreover the data need to be considered with respect to the sex and body weights.


We acknowledge the assistance of  Mr.Khalid , Saras Hospital Clinical Pathology Lab, Badarpur, Faridabad in getting the K.F.T data.


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