Quadrant -I (Video)
Estimation of blood urea
Quadrant - II (Study Material)
1. Estimation of blood urea
EXPERIMENT No. 6 ESTIMATION OF BLOOD UREA (BUN) (Diacetyl monoxime Method) BLOOD UREA : Urea is the major end product of protein catabolism. Amino acids on deamination yields ammonia which is neurotoxic. In the liver ammonia detoxified into urea by urea cycle. Urea is highly water soluble therefore excreted through urine. Being end product of protein, urea concentration varies with dietary intake of proteins even under normal healthy conditions. Abnormally increased blood urea level observed in diseased kidney, glomerulonephritis: nephrosis etc. Similarly in perirenal conditions such as enhanced protein catabolism. Dehydration, diarrhoea, vomiting and post renal conditions that obstruct the lower urinary tract e.g. enlarged prostate glands, strictures of urethra or stone in ureter etc. Decreased blood urea observed in hepatic disease such as hepatocellular Jaundice or cirrhosis due to impairment in ureagenic function of liver. PRINCIPLE : At higher temperature, diacetyl monoxime (on heating) form diacetyl. Urea reacts with diacetyl under strong acidic condition in presence of ferric ion and thiosemicarbazide to give a pink coloured diazine complex. The intensity of the pink colour is compared with a standard solution of urea treated similarly. REACTION : CH3 - CO - C - CH3 + H20 Δ CH3 - CO - CO - CH3 + NH4OH NOH , Diacetyl Diacetyl Monoxime (DAM) CH3 - CO - CO - CH2 + NH2 - CO - NH2 Acidic, Ferric ion (Fe+++), Thiosemicarbazide CH3 - C - C - CH3 N N + H2O Diacetyl Urea C Diazine Complex (pink) O Reagents : Mixed Colour Reagent - DAM, TSC Mixed acid reagent - H2SO4, FeCl3, Phosphotungstic acid Serum Std urea : 100 mg% ..24.. Procedure : Label three test tubes as S (Standard), T (Test) & B (Blank) make addition as follows to dilute the sample and standard. T (Test) S (Standard) B (Blank) 1) Diluted Serum 1 ml -- -- 2) Distilled Standard -- 1 ml -- 3) Dist. Water 1 ml 1 ml 1 ml 4) Mixed colour reagent 2 ml 2 ml 2 ml mix it well then add T (Test) S (Standard) B (Blank) 5) Mixed acid reagent 2 ml 2 ml 2 ml Again mix thoroughly. Then keep in boiling water bath for 20 minutes Cool and measure O.D. of the coloured solutions, using 520 nm green filter. Colour is stable for 24 hrs. at room temp, if kept in the dark. Observation : Filter used 520 mm green. Optical Density Absorbance of T = ................ Absorbance of S = ................ Conc.ofStd = 100mg% Calculations : Blood urea in mg% = S−BT−B x 100 Reference range : 15 - 45 mg% (mg/dl) Result : The concentration of urea in blood is........................................................... mg% Blood urea : Urea contains two atoms of nitrogen and its molecular weight is 60, of which 28 is due to nitrogen. Hence, the relationship of total blood urea to urea nitrogen is given by the ratio. 2860 = 2.14 Therefore Blood urea nitrogen (mg/dl) = 2.14Blood urea (mg/dl) i.e. Blood urea (mg/dl) = Blood urea nitrogen (mg/dl) x 2.14 ..25.. Reference range ; On ordinary diet, the reference range for blood urea nitrogen is 10 -18 mg/dl and that of blood urea is 15-40 mg/dl. Interpretation : Urea is the main end product of protein catabolism Its blood level depends on dietary intake of protein. It is synthesized in liver and constitutes a major nonprotein nitrogenous (NPN) substance. The condition, in which blood urea is increased, is called as uremia. This can be of three types. a. Pre-renal uremia: Decrease in blood volume: In dehydration due to prolonged diarrhoea, vomiting, burns, etc. The reduced plasma volume leads to low blood pressure, which decreases effective filtration rate in glomeruli and reduces filtration of urea. Increased tissue protein breakdown : In diabetes and in different types of fevers Hematemesis i.e. bleeding within the gastrointestinal tract . Cardiac failure and circulatory collapse due to other causes. b. Renal uremia : In this, increase in blood urea is due to improper functioning of the kidney. Nephritis Acute glomerulonephritis Renal tuberculosis Mercurial poisoning. ..26.. c. Post renal uremia : It is due to obstruction in the pathway of urinary excretion. Important causes of post-renal uremia are. Enlarged prostate Stone in the urinary tract Stricture of the urethra Tumors of the bladder affecting the ureteric junction Blood urea level decreases rarely. In certain terminal stages of liver failure, blood urea level is lowered. Use of blood urea estimation in the assessment of renal function : Since route of urea excretion is through kidneys, blood urea level is estimated to assess renal function. As blood urea level is affected by dietary protein and other pre-renal factors, serum creatinine estimation should also be done simultaneously. Results : Blood urea nitrogen = mg/dl Blood urea = mg/dl ..27..
2. Estimation of blood urea
Quadrant - III (Assignments)
1. Estimation of blood urea
Write the answer to the following question and upload it as PDF : Describe the principle, expected reference range, and clinical significance of the blood urea test by Diacetyl Monoxime method and how to interpret elevated or decreased blood urea levels in relation to kidney function.