Renal function tests
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Renal function tests

Renal function tests

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Renal function tests Renal function tests Presentation Transcript

  • RENAL FUNCTION TESTS
  • Vital role in body’s homeostasis
  • Functional unit of kidney is nephron Glomerular capillary network Bowman’s capsule Proximal tubule Loop of henle Distal tubule Collecting duct
  • STEPS IN URINE FORMATION GLOMERULAR FILTRATION TUBULAR REABSORPTION TUBULAR SECRETION
  •  RATE OF URINARY EXCRETION OF ANY SOLUTE = RATE OF GLOMERULAR FILTRATION + RATE OF SECRETION - RATE OF REABSORPTION
  • PHYSICAL TESTS i. URINE VOLUME  Assessment of fluid balance and kidney function. Normal value; adult : 800-2500 mL/day children : 500-1400 mL/day
  • CLINICAL IMPLICATIONS  1. polyuria with elevated BUN and creatinine . diabetic ketoacidosis partial obstruction of urinary tract tubular necrosis  2.polyuria with normal BUN and creatinine. diabetes mellitus and diabetes insipidus tumours of brain and spinal cord
  •  3.oliguria Renal causes renal ischemia renal disease due to toxic agents Dehydration caused by prolonged vomiting,diarrhoea,burns Obstruction of some area of the urinary tract Cardiac insufficiency  4.anuria Complete urinary tract obstruction Acute cortical necrosis Glomerulonephritis Acute tubular necrosis
  • INTERFERING FACTORS  1.polyuria a)intravenous glucose or saline b)thiazides c)coffee,alcohol,tea,caffeine  2.oliguria a)dehydration b)excessive salt intake
  • 2.URINE COLOUR  Yellow colour due to urochrome.  Normal; Pale yellow to amber Straw colour- low SG Amber colour-high SG
  • CLINICAL IMPLICATIONS  Almost colourless urine; large fluid intake chronic interstitial nephritis untreated diabetes mellitus diabetes insipidus alcohol and caffeine ingestion diuretic therapy nervousness  Orange colour; fever carrots or vitamin A phenazopyridine, nitrofurantoin
  •  Green urine; pseudomonal infection chlorophyll  Red urine RBCs haemoglobin myoglobin porphyrins  Black urine melanin phenol poisoning  Smoky urine - RBCs  Milky urine - fat,cystinuria,WBCs
  • INTERFERING FACTORS  Colour darkens on standing  Drugs alter the colour green - indomethacin brown - chloroquine,furazolidone pink to brown - laxatives red-pink - daunorubicin orange - rifampicin blue urine - triamterene black urine - chloroquine metronidazole
  • 3.URINE ODOUR  Faint odour owing to the presence of volatile oils. normal; aromatic odour.
  • CLINICAL IMPLICATIONS  Diabetes mellitus patients urine have a fruity odour.  UTIs result in foul-smelling urine .  Infants with a inherited disorder of amino acid metabolism urine smells like burnt sugar.  Cystinuria result in sulfurous odour.
  • 4.URINE SPECIFIC GRAVITY (SG)  Measurement of the kidneys ability to concentrate urine.  Compares the density of urine against the density of distilled water.  Normal; 1.005-1.030
  • CLINICAL IMPLICATIONS  Hyposthenuria ( low SG,1.001-1.010) diabetes insipidus  Hypersthenuria(increased SG, 1.025- 1.035) diabetes mellitus nephrosis excessive water loss congestive heart failure
  • INTERFERING FACTORS  Elevated readings Moderate amounts of protein Patients receiving intravenous albumin. Diuretics and antibiotics
  • 5. URINE pH  pH is an indicator of the renal tubules ability. normal; can vary widely 4.6 - 8 average value is about 6 (acidic).
  • CLINICAL IMPLICATIONS  1. Acidic urine (pH<7.0) Starvation UTIs caused by Escherichia coli respiratory acidosis pyrexia  2. Alkaline urine (pH>7.0) UTIs caused by urea-splitting bacteria renal tubular acidosis respiratory alkalosis potassium depletion
  • INTERFERING FACTORS  alkaline urine Sodium bicarbonate potassium citrate acetazolamide  acidic urine ammonium chloride mandelic acid
  • CHEMICAL EXAMINATION OF URINE  ENDOGENOUS MARKERS a) SERUM CREATININE (kreas) breakdown product of muscle creatine phosphate. excreted by glomerular filtration and tubular secretion. doubles with each 50% decrease in GFR. if SCr is 1mg/dl, 100% renal function 2mg/dl, 50% renal function
  •  Normal; URINE CREATININE men : 14-26mg/kg/24 hours women: 11-20mg/kg/24 hours SERUM CREATININE men : 0.6-1.2 mg/dL women : o.4-1.0 mg/dL
  • CLINICAL IMPLICATIONS  SERUM CREATININE increased in; ingestion of roast meat muscle disease prerenal azotemia postrenal azotemia decreased in; pregnancy
  • SERUM CREATININE INCREASED BY DECREASED BY ACE inhibitors Ascorbic acid Alprazolam Captopril Aspirin Dopamine Cefixime Valproic acid Methotrexate Prednisone Ranitidine Triamterene Ibuprofen
  • CLINICAL IMPLICATIONS URINE CREATININE Increased by decreased by Acromegaly Anemia Hypothyroidism Leukemia Gigantism Diabetes mellitus Muscular dystrophy Hyperthyroidism
  • URINE CREATININE INCREASED BY DECREASED BY Ascorbic acid Anabolic steroids Corticosteroids Captopril Methotrexate Thiazides Methyldopa Ketoprofen Cefoxitin
  • CREATININE CLEARANCE  Rate at which creatinine is removed from the blood.  Useful measure of glomerular filtration rate excreting capacity of the kidney.
  •  Normal values; men : 90-140 ml/sec/m² women: 72-110 ml/sec/m²
  • SCHWARTZ FORMULA crcl(ml/min) = k x ht in cm/scr(mg/dl) k = 0.45 ,infants < 1 year of age k = 0.55 ,children and adolescent females. k = 0.7, adolescent males.
  • COCKCROFT-GAULT equation  CrCl = (140-age) x weight(kg) 72 x SCr (mg/dl) X 0.85
  • CLINICAL IMPLICATIONS INCREASED State of high cardiac output pregnancy burns carbon monoxide poisoning DECREASED Impaired kidney function dehydration hemorrhage congestive heart failure
  • INTERFERING FACTORS  Exercise may increase creatinine clearance and urine creatinine.  Pregnancy increases CrCl  Proteinuria and advanced renal failure make CrCl an unreliable method for determining GFR.
  • BLOOD UREA NITROGEN  End product of protein metabolism (liver)  It travels through the blood and is excreted by the kidney.  BUN measures the amount of nitrogen in the blood in the form of urea.
  •  Normal value; Adults : 6-20 mg/dl Elderly patients : 8-23 mg/dl Children : 5-18 mg/dl AZOTEMIA; excessive retention of nitrogenous waste products. Renal azotemia ; renal disease (glomerulonephritis and chronic pyelonephritis). Prerenal azotemia; severe dehydration hemorrhagic shock excessive protein intake. Postrenal azotemia; urethral stones tumours prostatic obstructions.
  • CLINICAL IMPLICATIONS  1.Increased BUN levels (azotemia) a.impaired renal function congestive heart failure salt and water depletion stress acute MI b. chronic renal diseases c. Urinary tract obstruction d. hemorrhage into GI tract. e. diabetes mellitus  2. Decreased BUN levels a. liver failure b. acromegaly c. malnutrition
  • INTERFERING FATCORS  Decreased BUN levels late pregnancy combination of a low protein and high carbohydrate diet.
  •  ACE inhibitors  Indomethacin  Penicillin  Thiazides  Rifampin  Spironolactone  Timolol  Cefotaxime  Phenothiazines  Chloramphenicol  Levodopa  Amikacin • BUN increased by  BUN decreased by
  • GLOMERULAR FILTRATION RATE  GFR is the volume of water filtered or cleared out of the plasma per minute.  GFR is approximated by measuring the urinary excretion rate of a marker substance.  Example for marker inulin.
  •  Normal value; Average GFR in young male adult: 120ml/min/1.73m²
  • URINE PROTEINS  Increased amounts of protein is an important indicator of renal diseases.  Normal value; Adult male:10-140 mg/dl Female:30-100 mg/dl
  • CLINICAL IMPLICATIONS  Proteinuria Glomerular damage Diminished tubular reabsorption Renal artery stenosis Tumours Renal transplant rejection
  • INCREASED BY  Mefenamic acid  Theophylline  Penicillin  Furosemide  Carbamazepine
  • URINE GLUCOSE  Present in glomerular filtrate and is reabsorbed by the PCT.  Blood glucose level >reabsorption capacity glucose
  •  Normal values;  Random specimen : negative  24-hour specimen :1-15 mg/dl
  • CLINICAL IMPLICATIONS Increased glucose diabetes mellitus liver and pancreatic disease endocrine disorders impaired tubular reabsorption Increase of other sugars Lactose - pregnancy,lactation Xylose - excessive ingestion of fruit
  • URINE GLUCOSE  Increased by Chlorpromazine Phenytoin Ofloxacin Sulfonamide Tetracycline  Decreased by Ampicillin Insulin Carvidopa Furosemide
  • URINE SODIUM  Helps to regulate acid-base balance.  Normal value; adult : 40-220 mEq/24 hours child : 41-115 mEq/24 hours
  • CLINICAL IMPLICATIONS  Increased sodium Adrenal failure Renal tubular acidosis Diabetic acidosis  Decreased sodium Excessive sweating Congestive heart failure Cushing’s disease
  • SODIUM IN URINE  Verapamil  Clofibrate  Aspirin  atenolol  Omeprazole  Propranolol  Ramipril  lithium  INCREASED BY  DECREASED BY
  • URINE POTASSIUM  Vital function in the body’s overall electrolyte balance. normal; adult : 25-125 mEq/24 hours child : 10-60 mEq/24 hours
  • CLINICAL IMPLICATIONS  Primary renal disease  Starvation  Diabetic and renal tubule acidosis  Cushing’s syndrome  Addison’s disease  Severe renal disease  INCREASED POTASSIUM  DECREASED POTASSIUM
  • POTASSIUM IN URINE  Oral contraceptives  Chlorthalidone  Antibiotics  Isosorbide  Diuretics  Anesthetic agents  Felodipine  Ketoconazole  Trimethoprim  Ramipril  INCREASED BY  DECREASED BY
  • URINE CHLORIDE  Diagnose dehydration or as a guide in adjusting fluid and electrolyte balance.  Also useful in monitoring the effects of reduced salt diets( CVD,HTN)  Normal value; adult: 140-250 mEq/24 hours child : 64-176 mEq/24 hours
  • CLINICAL IMPLICATIONS  Increased salt intake  Adrenocortical insufficiency  Potassium depletion  Vomiting,diarrhoea  Gastric suction  Addison’s disease  Cushing’s syndrome  Conn’s syndrome  INCREASED CHLORIDE  DECREASED CHLORIDE
  • URINE CHLORIDE  Ammonium chloride administration  Excessive infusion of normal saline  Ingestion of sulfides, cyanides, halogens, bromides and sulfhydril compounds.  Carbenicillin therapy  Reduced dietary intake of chloride  Ingestion of large amounts of licorice  Alkali ingestion  Dehydration  INCREASED CHLORIDE  DECREASED CHLORIDE
  • URINE KETONES  From fatty acid and fat.  Consists mainly of three substances : acetone, β-hydroxybutyric acid acetoacetic acid. normal value; urine: negative (<0.3 mg/dl)
  • CLINICAL IMPLICATIONS  Hyperthyroidism  Fever  Pregnancy or lactation  Diabetes mellitus  Starvation  Anorexia  INCREASED METABOLIC STATES  DECREASED METABOLIC STATES
  • KETONES IN URINE  Amino salicylic acid  Cefixime  Valproic acid  Dimercaprol  Captopril  Aspirin  Phenazopyridine  INCREASED BY  DECREASED BY
  • MACROSCOPIC EXAMINATION of centrifuged urine.  1) Hematuria it indicates trauma, tumour, systemic bleeding.  2) casts Casts are cylindrical elements with parallel sides
  • HYALINE CASTS Particularly in dehydration
  • RED CELL CASTS  Glomerulonephritis
  • WHITE CELL CAST  Pyelonephritis
  • GRANULAR CASTS  Renal parenchymal disease  Dehydration
  • EPITHELIAL CAST  Tubular damage
  • EXOGENOUS MARKERS  INULIN CLEARANCE normal value; men : 127ml/min/m² women: 118ml/min/m²  Fructose polysaccharide.  Patient receives inulin to achieve a steady blood concentration.  The quantity in plasma and the amount excreted in urine is measured.
  • IOTHALAMATE  Normal value; men : 127 ml/min/m² women: 118 ml/min/m²  Injection of the radioactive exogenous marker .  These are not widely used.
  • REFERENCES  A manual of laboratory and diagnostic tests; by Frances Fischbach, Marshall B.Dunning, Edition 8.  Textbook of therapeutics; Drug and disease management by Eric.T.Herfindal,sixth edition.  Comprehensive pharmacy review by Leon shargel,fourth edition.  Basic skills in interpreting laboratory data by Mary Lee,fourth edition.  Principles of anaatomy and physiology by Tortora, tenth edition.
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