Urea creatinine
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Transcript of Urea creatinine
Tapeshwar Yadav(Lecturer)BMLT, DNHE, M.Sc. Medical Biochemistry
Urea is the major end product of protein metabolism In humans.
Its formed in liver. Urea biosynthesis occurs in four stages: (1) transamination, (2) oxidative
deamination of glutamate, (3) ammonia
transport, (4) reactions of the
urea cycle
ammonia is produced in various ways by tissues are rapidly removed from circulation by the liver and converted to urea. This is essential, since ammonia is toxic to the central nervous system.
Urea is water soluble ,conversion of ammonia to urea is a kind of detoxification.
This is the importance of urea excretion and its estimation.
Any defect in any of the enzyme function of urea cycle can lead to various metabolic disorders.
More than 90% of urea is excreted through the kidneys(glomeruli), with losses through GIT and skin in minor fraction.
Determination of blood urea is important not only in many diseases of kidney but in a wide range of conds which r not primarily renal.
Causes of increase in serum urea
Causes r divided in pre-renal , renal and post-renal
PRE-RENAL :
dehydration pyloric n intestinal obstruction with vomiting sever n prolonged diarrhea chrn intestinal obstruction without vomiting ulcerative colitis with severe chloride loss diabetic coma
RENAL : acute glomerulonephritis malignant hypertension chronic pyelonephritis hydronephrosis congenital cystic kidney renal tuberculosis calcium deposition in kidney in hyperthyroidism n
hypervitaminosis D.
POST RENAL: enlargement of prostate
stones in urinary tract
stricture of the urethra
tumors of the bladder affecting the ureter
Cirrhosis of liver
Acute yellow atrophy of liver
Severe acidosis
Nephritis
Pregnancy
BLOOD UREA: Diacetyl monoxime method principle
when urea is heated with diacetyl(,containing two adjacent carbonyl group) under acidic condition yellow coloured compound is formed.the OD of the colour developed can be read at 420 nm.intensity of the color depends on conc of urea in serum.
additions BLANK STANDARD TESTProtein free filtrate
_ _ 1ml
Working standard _ 1ml _Distilled water 1ml _ _DAM reagent 0.4ml 0.4ml 0.4mlAcid mixture 1.6ml 1.6ml 1.6ml
OD of the test × conc of standard × 100 OD of the standard vol of the test
= T/S×100
BUN(blood urea nitrigen): = blood urea level× 28/60
Normal value - 5 -20 mg/dl
Principle: urease hydrolyses urea to ammonia and
CO2.the ammonia formed further reacts with a phenolic chromogen and hypo chloride to form a green colored complex. Intensity of colour is directly proportional to the amount of urea present in the sample. addition blank standard test
Working reagent
1.0 ml 1.0ml 1.0ml
Distilled water
0.01ml - -
Urea standard
- 0.01ml -
sample - - 0.01mlChorogen reagent
0.2ml 0.2ml 0.2ml
calculation: = T/S × 40
SERUM – 15 to 40mg/dl
The hypobromite method Principle: the vol of nitrogen liberated by the action of
hypobromite on the urea present in the urine is measured. the action is usually though not accurately, expressed
URINE - 15 to 30mg/day.
Urea clearance is less than GFR.Maximum urea clearance: =U × V/P U=mg of urea /ml of urine p=mg of urea/ml of plasma v=mg of urine excreted /minute
normal value - 75 ml /mint
Standard urea clearance: u × √v/p
normal value - 54ml/mint
Values below 75% is abnormal
Values fall progressively with increasing renal failure
Clearance values r the early indicator then plasma value
creatinine clearance is more preferred
Neither urea clearance nor blood urea r used as index of kidney function today
Creatine constitutes about 0.5% of total muscle weight. Its synthesized from 3 amino acids Glycine , Arginine &
Methionine. glycine arginine (occurs in mitochondia of kidney n
pancreas) Guanidoacetic acid ornithine SAM (in liver) SAH Creatine creatine phosphate (ck is pesent in muscle brain
n liver)
creatinine
CREATINE creatine kinase PHOSPHOCREATINE
SPONTANEOUS SPONTANEOUS
H₂O Pi
CREATININE
Stored creatine phosphate which is a high energy compound, stored in the muscle, serves as an immediate store of energy.
Inter conversion of phosphocreatine & creatine is an indicator of metabolic process of muscle contraction.
A particular proportion of muscle creatine is converted to creatinine spontaneously everyday.
So amount of creatinine produced in body is related to muscle mass .
Conc. Of creatinine in blood is mostly constant. Diet may influence the value with high meat intake. Its freely filtrated by glomerulus. Its an indicator of renal function.
Increased conc of creatine
Muscular disorders Myasthenia gravis Different myositis Starvation High fever Diabetes mellitus Hyperthyroidism
Causes of increase in serum Creatinine
Causes are divided in pre-renal , renal and post-renal
PRE-RENAL : Dehydration Pyloric & intestinal obstruction with vomiting Severe n prolonged diarrhea Chronic intestinal obstruction without vomiting Ulcerative colitis with severe chloride loss Diabetic coma
RENAL : Acute glomerulonephritis Malignant hypertension Chronic pyelonephritis Hydronephrosis Congenital cystic kidney Renal tuberculosis Calcium deposition in kidney in hyperthyroidism &
hyper-vitaminosis D .
POST RENAL: Enlargement of prostate
Stones in urinary tract
Stricture of the urethra
Tumors of the bladder effecting the ureter
Increased conc of creatinine
Conditions r same as increased urea conc. But in renal causes creatinine increases more
than the pre-renal causes.
Jaffe`s method (in urine) principle: creatinine in urine reacts with picric
acid in presence of NaOH to give orange colored compound.creatinine-picrate color read at 500 nm.
addition
BLANK STANDARD
TEST
Distilled water
3ml - -
Working standard
- 3ml -
Diluted urine
- - 3ml
Picric acid 1ml 1ml 1ml0.75 N NaOH
1ml 1ml 1ml
calculation: =gms of creatinine /lt =T/S×0.03/1000×1000/0.03 =T/S gm/lt
Normal value – 1 - 1.5gm/lt
Modified jaffe`s reaction: principle: cretinine reacts with alkaline
picrate to produce a reddish color. Absorbance of the color is directly proportional to creatinine conc in plasma n its measured in 500-520nm.
addition
blank standard
sample
Working reagent
- 1000ùl 1000ùl
Standard - 100ùl -serum - - 100ùl
Calculation: =T/S ×conc of standard(mg/lt)(2mg/dl)
normal value – 0.7 -1.4mg/dl (male) 0.6 – 1.2 mg/dl (female)
Uncorrected clearance =(u/p)× v
U=urinary creatinine conc. p=plasma creatinine conc v=urine flow in ml/min
Corrected clearance =u×v×1.73
p×A
Normal value: 85-125 ml/min (male) 80-115 ml/min (female)Clinical importance decreased creatinine clearance is an sensitive
indicator of GFR. UPTO 75% is nornal. Early detection of renal impairment Long term monitoring of renal patients Creatinine clearance is altered by body muscle mass
,drugs,age,sex