urea generation - (a) High protein diet. (b) Upper Gl bleedng. (c) Catabolic Illness. (d) Corticosteroid or tetracycline
Increased tubular urea resorption -(a) Dehydration (b) Salt depletion. (c) Hypotention Both factors may coexist.radioisotope marker clearance: 51Cr-EDTA and 125I-iothalamate ara excreted entirely by glomerular fiftration The substance is lnjected i.v. and clearance determined by measurement ol radioactivity in plasma or urine the test is most appropriate for assessment of renal function in patients with normal or near normal plasma creatinine. Technetium dethylamine penta-acetic acid (DTPA) is injected iv;the rate of excretion is followed by surface scanning of the kidneys, to determine if renal function is divioded equally between the kidneys Radiocontrast agent clearance Assessing the blood clearance of these agents after i.v. Injection is useful in patients in whom GFR is changing rapidly. (e.g. evolving or recovering acute renal failure). IlI. Assessment of filtration barrier Normal filtration barrier is impervious to molecules of molecular wt. > about 60.000 Daltons. Proteinuria - (a) In glomerular injury, the amount of albumin increases. (b) Microalbuminuria helps early detection of dabetic nephropathy. (c) Assessing the 'selectivity' filtration barrier by calculating the proportional claarance of a large molecule. such as lg-G (150,000 Daltons) compared with a small molecul such as albumin (66.500 Daltons) is of use in childrean with nephrotic syndrome, a selectivity index <0.10>1015) In more formal tests.fluid deprivaiion for upto 24- hrs or injection of antiduratic hormone (vasopressin tannate) should increase urinary osmolality to 750 mOsmol/1 or more. 2. Urinary acidifition - Kidneys must axcrate 70-100 m mol of non-valatile acids/'day. otherwise plasma pH 'falls and urine pH is high. ph of urine can be assessed by dipstic A more formal testl is the add load test Ammonium chloride 100 mg/kg is given orally over 30-60 minutes (to avoid vomiting). Urine pH and plasma bicarbonate are measured over 3 hrs. "the Bicarbonate concerrtration should falI below 18 mmol/1 and urine pH below 5.3. In metabolic acidosisr plasma bicarbonate is allready <>
Increased tubular urea resorption -(a) Dehydration (b) Salt depletion. (c) Hypotention Both factors may coexist.radioisotope marker clearance: 51Cr-EDTA and 125I-iothalamate ara excreted entirely by glomerular fiftration The substance is lnjected i.v. and clearance determined by measurement ol radioactivity in plasma or urine the test is most appropriate for assessment of renal function in patients with normal or near normal plasma creatinine. Technetium dethylamine penta-acetic acid (DTPA) is injected iv;the rate of excretion is followed by surface scanning of the kidneys, to determine if renal function is divioded equally between the kidneys Radiocontrast agent clearance Assessing the blood clearance of these agents after i.v. Injection is useful in patients in whom GFR is changing rapidly. (e.g. evolving or recovering acute renal failure). IlI. Assessment of filtration barrier Normal filtration barrier is impervious to molecules of molecular wt. > about 60.000 Daltons. Proteinuria - (a) In glomerular injury, the amount of albumin increases. (b) Microalbuminuria helps early detection of dabetic nephropathy. (c) Assessing the 'selectivity' filtration barrier by calculating the proportional claarance of a large molecule. such as lg-G (150,000 Daltons) compared with a small molecul such as albumin (66.500 Daltons) is of use in childrean with nephrotic syndrome, a selectivity index <0.10>1015) In more formal tests.fluid deprivaiion for upto 24- hrs or injection of antiduratic hormone (vasopressin tannate) should increase urinary osmolality to 750 mOsmol/1 or more. 2. Urinary acidifition - Kidneys must axcrate 70-100 m mol of non-valatile acids/'day. otherwise plasma pH 'falls and urine pH is high. ph of urine can be assessed by dipstic A more formal testl is the add load test Ammonium chloride 100 mg/kg is given orally over 30-60 minutes (to avoid vomiting). Urine pH and plasma bicarbonate are measured over 3 hrs. "the Bicarbonate concerrtration should falI below 18 mmol/1 and urine pH below 5.3. In metabolic acidosisr plasma bicarbonate is allready <>
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