RFT.pptx Renal function tests are divided into the following Urine analysis Blood examination Glomerular Function Test Tubular Function Test
- 2. Kidney Functions Excretory • Formation and excretion of urine • Glomerular filtration • Tubular reabsorption • Tubular secretion • Excreting toxic substances in synergy with liver Homeostatic • Regulation of blood volume • Regulation of blood pH • Regulation of serum electrolytes; Na, K, Cl and Ca • Reabsorption of essential nutrients
- 3. Endocrine • Erythropoietin • Renin Angiotensin system • Vitamin D activation • Degradation of hormones like insulin and aldosterone Metabolic • Along with liver site for gluconeogenesis
- 4. Renal function tests; Why needed? To assess functional capacity of kidneys To diagnose renal impairment To assess the severity and progression of renal impairment To assess the effectiveness of treatment Monitor the safe and effective use of drugs which are excreted in the urine
- 5. When should we assess renal function? •Older age •Family history of Chronic Kidney disease (CKD) •Decreased renal mass •Diabetes Mellitus (DM) •Hypertension (HTN) •Autoimmune disease •Systemic infections •Urinary tract infections (UTI) •Nephrolithiasis •Obstruction to the lower urinary tract •Drug toxicity
- 6. Causes of renal disease Pre-renal • Any condition that results in reduced blood flow to kidneys • Severe blood loss • Hemolysis Renal • Damage to renal tissue, glomerular basement membrane or tubules • Glomerulonephritis • Diabetic or hypertensive nephropathy • Tubular damage due to toxic substances Post Renal • Obstruction to urine outflow • Ureteric or urethral stone • Prostatic cancer
- 7. Renal function test Renal function tests are divided into the following Urine analysis Blood examination Glomerular Function Test Tubular Function Test
- 8. Renal function test The following parameters are commonly included in assessing renal function (the normal values/reference range is mentioned) • Serum Urea ( 15-45 mg/dl) • Serum Creatinine (0.6 – 1.2 mg/dl) • Serum Uric acid (males 3.5-7.2 mg/dl, females 2.6-6 mg/dl) • Total protein (6.4-8.1 g/dl) • Serum albumin (3.2-4.6 g/dl) • Serum electrolytes • Na (136-146 mEq/L) • K (3.5-5.1 mEq/L) • Cl (101-109 mEq/L) • Phosphate (2.8-4 mg/dl) • Calcium (8.8-10.2 mg/dl)
- 9. Complete hemogram Hemoglobin total RBC RBC indices MCH (Mean corpuscular hemoglobin) MCV (Mean corpuscular volume PCV (Packed cell volume) MCHC (Mean corpuscular Hemoglobin concentration) ESR
- 10. Urine Analysis • includes physical or macroscopic examination, chemical examination and microscopic examination of the sediment
- 11. Colour Blue Green Pink-Orange- Red Red-brown-black Methylene Blue Haemoglobin Haemoglobin Pseudomonas Myoglobin Myoglobin Riboflavin Phenolpthalein Porphyrins Red blood cells Homogentisic Acid Rifampicin L -DOPA Melanin Methyldopa Colour of urine depending upon it’s constituents.
- 12. Specific Gravity • Measured by urinometer or refractometer. • It is measurement of urine density which reflects the ability of the kidney to concentrate or dilute the urine relative to the plasma from which it is filtered. • Normal :- 1.001- 1.040 S.G Osmolality (mosm/kg) 1.001 100 1.010 300 1.020 800 1.025 1000 1.030 1200 1.040 1400
- 13. Specific Gravity Increase in Specific Gravity seen in • Low water intake • Diabetes mellitus • Albuminuruia • Acute nephritis. Decrease in Specific Gravity is seen in • Absence of ADH • Renal Tubular damage. Isosthenuria-Persistent production of fixed low Specific gravity urine isoosmolar with plasma despite variation in water intake
- 14. Urine Analysis
- 15. Blood examination to measure substance in blood that are normally excreted by kidney. their level in blood increases in kidney dysfunction. markers of renal function creatinine, urea, uric acid and electrolytes are done for routine analysis
- 16. Serum creatinine • Creatinine is filtered but not reabsorbed in kidney • Not increased above normal until GFR<50 ml/min • The methods most widely used for serum creatinine are based on the Jaffe reaction. This reaction occurs between creatinine and the picrate ion formed in alkaline medium (sodium picrate); a red-orange solution develops which is read colorimetrically at 520 nm
- 17. Blood urea • major nitrogenous end product of protein and amino acid catabolism • filtered freely by the glomeruli • Many renal diseases with various glomerular, tubular, interstitial or vascular damage can cause an increase in plasma urea concentration • High protein diet causes significant increases in plasma urea concentrations and urinary excretion • Enzymatic Berthelot Method is used for blood urea estimation
- 18. Plasma Cystatin C one of the latest small molecular weight proteins to be considered and used as KFT also seems to be subject to the tubular mechanisms for handling low molecular mass proteins, the rate of hepatic protein synthesis, and thyroid dysfunction
- 19. Serum Uric Acid uric acid is the major product of the catabolism of the purine nucleosides, adenosine and guanosine Overproduction of uric acid may result from increased synthesis of purine precursors may increase in chronic kidney disease but not sufficient to cause gout raised uric acid is a bad prognostic indicator for chronic renal disease
- 20. Total protein and albumin Both serum total protein and albumin is decreased in chronic kidney disease (CKD) due to increased proteinuria Even though proteinuria may also be seen in acute kidney disease but it usually does not alter the total protein and albumin
- 21. Serum electrolytes Sodium is decreased (hyponatremia) and potassium is increased (hyperkalemia) in chronic kidney disease (CKD) as kidney reabsorb sodium in exchange of potassium Chloride and phosphate is increased in CKD Calcium is decreased as vitamin D is deficient
- 22. CBC decreased in advanced stages of kidney disease due to deficiency of erythropoietin
- 23. Clearance test • Clearance of substance is defined as the volume of plasma that is cleared of that substance in unit time • Inulin clearance accurately measures GFR as it is neither secreted or absorbed by the renal tubules; 51 Cr-EDTA •However it is not routinely done in patients. • In clinical setting estimated GFR (eGFR) is more commonly used; it is calculated from serum creatinine value
- 24. Clearance •U = Concentration of the substance in urine. •V = Volume of urine in ml excreted per minute. •P = Concentration of the substance in plasma
- 25. Creatinine Clearance Test • Creatinine is an excretory product derived from creatine phosphate. • The excretion of creatinine is rather constant & is not influenced by body metabolism or dietary factors. • Creatinine is filtered by the glomeruli & only marginally secreted by the tubules
- 26. GFR Significance State Grade GFR ml/mt/1.73m2 Minima damage with normal GFR 1 >90 Mild damage with slightly low GFR 2 60-89 Moderately low GFR 3 30-59 Severely low GFR 4 15-29 Kidney failure 5 <15
- 27. •Cockroft Gault Formula • Creatinine Clearance =(140-age)* weight in kg / S.creat.*72 • (multiplied by 0.85 for females) •MDRD Nomogram • GFR(ml/min)=170*S.creat.-0.999 *age-0.176 * BUN-0.170 *albumin0.318 • (multiplied by 0.742 if female)
- 28. Urea Clearance Test • Urea is the end product of protein metabolism. • After filtered by the glomeruli, it is partially reabsorbed by the renal tubules. • Urea clearance is less than the GFR & it is influenced by the protein content of the diet. • Urea clearance is not as sensitive as creatinine clearance
- 29. Tests for tubular function Urine Concentration Test • The ability of the kidney to concentrate urine • This test requires a water deprivation for 14 hrs in healthy individuals. • A specific gravity of > 1.02 indicates normal concentrating power. • Specific gravity of 1.008 to 1.010 is isotonic with plasma and indicates no work done by kidneys. • The test should not be performed on a dehydrated patient
- 30. TFT Vasopressin Test Urine Dilution (Water Load) Test • After overnight water deprivation patient is asked to take 1200ml of water in half hour, urine specific gravity is measured in samples collected over next 4 hours. At least one sample should show sp gr of 1.003 or below • The test should not be done if there is oedema or renal failure; water intoxication may result
- 31. TFT Para Aminohippuric Acid Clearance • PAH is unique in that it is completely excreted in one passage through kidney as it is both filtered and secreted • Maximum secretory capacity of tubules for PAH is nearly constant at about 80mg/min. • A decrease in the TmPAH indicates tubular damage
- 32. TFT Acidification test • In this the ability to acidify urine is tested after administering 0.1g/kg ammonium chloride gelatin coated samples
- 33. TFT Micropuncturing • Micropuncturing various part of tubule and analysis of fluid for volume and composition. Microcryoscopic study • Studying slices of renal tissue at different depths. Microelectrode study • Measuring membrane potential of the tubular cells
- 34. Enzymes in urine useful in detection of acute renal damage specifically, proximal tubular damage • Cytosolic lactate dehydrogenase (LDH) proximal tubular brush border enzymes • alanine aminopeptidase (AAP) • leucine arylamidase • gamma glutamyl transferase • alpha-glutathione S-transferase distal tubular enzyme • rat tau-glutathione S-transferase lysosomal enzyme • N-acetyl-beta-glucosaminidase (NAG)