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UREA TEST
UREA TEST
Definition :-
-Urea is formed in the liver through enzymatic breakdown of protein.
– Filtered by glomerulus , small amount reabsorbed in the tubules , the remainder is excreted in the urine.
-Elevation in blood called azotemia and may be a result of prerenal, renal or post renal reasons.
-Prerenal may be under factors that result inadequate renal circulation or high blood level of protein.
-Renal etiologies are those of impaired renal filtration and excretion of urea.
– Post renal etiologies are obstructions of lower urinary tract result in diffusion of urea back into blood through tubules. Uremia is a term to describe symptoms resulting from elevation of urea in blood of about 200 mg/dl and more.
Clinical Significance :-
Increased in : Impaired kidney function and
Increased in : Impaired kidney function and
decreased renal perfusion as in congestive heart failure ( CHF) , dehydration, shock in combination with increase protein catabolism as in GIT bleeding , burns, AMI , stress, acute or chronic renal disease, post renal obstruction to urine flow, high protein diet.
Decreased in :- Low protein , increased utilization of proteins for synthesis , late pregnancy , acromegaly , IV feeding only , sever liver damage , drug poisoning and impaired absorption [Celiac disease ].
Methodology :-
Diacetyl monoxime , urease / chromogen and , urease / GLDH.
Guiding Reference Value :-
Adult 13 – 43 mg/dl.
60 – 90 years 17 – 49 mg/dl.
>90 years 21 – 66 mg/dl.
Limitation :-
– Some drugs cause elevation of urea levels such as: – corticosteroids , tetracyclines , excess thyroxine , androgens , methyldopa , morphine , nalidixic acid and vancomycin.
– Streptomycin , growth hormone , thymol cause reduction in blood level.
-Plasma or serum level in higher than blood level by about 12%.
– In sever hepatic disease liver unable to synthesize urea from protein result in build up of blood ammonia causing hepatic encephalopathy.
UREA TEST
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