RENAL FUNCTION TESTS.ppt
- 2. Why Important? • Mostly the kidney diseses are asymptomatic or have vague/nonspecific symptoms so Renal function tests are useful tests for estimation of renal function before any radiological procedure, in chronic diseases which effect kidney like HTN, DM and for general wellbeing.
- 3. FUNCTIONS OF KIDNEY • Excretes the waste products of metabolism • Precisely regulates the body’s concentration of water and salt • Maintains the appropriate acid base balance of plasma • Serves as an endocrine organ, secreting such hormones as erythropoietin, renin, and prostaglandins. • Conversion of Vit D into active Vit D3 form
- 4. Kidney carries out filtration of blood to form urine! The total blood volume is circulated through the kidneys about 300 times each day serves to convert more than 1700 liters of blood per day into about 1 liter of a highly specialized concentrated fluid called urine.
- 5. Basic RFTs • In Blood sample: BUN/UREA Serum Creatinine BUN and creatinine rise in kidney dyfunction.
- 6. BUN-Blood urea Nitrogen and Urea • Urea is a relatively nontoxic substance made by the liver to dispose of ammonia resulting from protein metabolism. • The real urea concentration is BUN x 2.14 • Normal BUN range is 8-25 mg/dL • BUN is a sensitive but not specific indicator of renal disease—can be raised in dehydration, CCF, Urinary tract obstruction
- 7. Serum creatinine • Creatine is made by body to supply energy to muscles. Muscles use creatine and form a byproduct creatinine as waste of creatine, kidney filters it from blood along with other waste products • In Kidney failure creatinine cannot be excreted properly by kidney so its level rises in blood
- 8. Serum CREATININE • It is generally a more sensitive and specific test for renal function than the BUN. • Normal range is 0.6-1.3 mg/dL • – *non pregnant state • % rise in urea and creatinine more useful in kidney diseases rather than single value bc each individual has different normal value depending upon his age, sex and body mass
- 9. AZOTEMIA? & UREMIA? • Azotemia is a biochemical abnormality that refers to an elevation of the blood urea nitrogen (BUN) and creatinine levels, and is related largely to a decreased glomerular filtration rate (GFR). • Types of azotemia: Prerenal azotemia (e.g., in hemorrhage, shock, volume depletion, and congestive heart failure)
- 10. Postrenal azotemia is seen whenever urine flow is obstructed beyond the level of the kidney • UREMIA: When azotemia becomes associated with a constellation of clinical signs and symptoms and biochemical abnormalities,it is termed Uremia. • S&S of uremia: Nonspecific: Nausea, vomiting, fatigue, sleep disturbances, leg cramps, Amenorrhea etc
- 12. Tests to estimate the rate of filtration of blood by kidney— Kidney function Creatinine clearance eGFR(Estimated GFR) • Both tests actually estimate the kidney function by estimating the filtration rate of creatinine, only estimate bc using creatinine and not whole blood as indicater which is not absorbed by tubules after filtration and secreted in very small amount
- 13. How CC is performed? • Patient collects his urine in container for oneday/24hours and then his blood sample taken for serum creatinine--- • Than both urine creatinine and serum creatinine levels put in formula to estimate the amount of creatinine cleared from body by kidney thus tells weather kidney functioning normally
- 15. eGFR • Nowadays eGFR is used instead of CC • Calculated by different formulas in which modifying factors age,sex,race and surface area applied along with serum creatinine • Timed urine creatinine collection not required
- 16. What is GFR?-Glomerular filtration rate sum of the filtration rates-amount/time filtered in all of the functioning nephrons
- 17. GFR decreases with chronic kidney failure
- 18. What is normal GFR value??
- 19. Estimated GFR bc creatinine used as a substance whose clearance is measured and not whole blood
- 20. Other tests • Urine R/E and microscopic examination: Gross/microscopic hematuria, RBCs Casts, WBCs and WBCs casts, Urine sediments/crystals • For Microalbuminurea--- 24 hours urine analysis or Spot urine protein/creatinine ratio(Spot PCR)
- 21. Other tests for kidney diseases…. • Serum Albumin • Serum electrolytes • Serum cholesterol USG: size of kidney; cortico-medullary delineation Optional: Viral serology (HIV, HBV, HCV), ASLO titer, ANA / dsDNA/ ANCA, serum complement (C3, C4) level
- 22. URINE ANALYSIS • Macroscopic or physical examination • Color : pale yellow- normal • Cloudiness, different colors • ODOUR
- 23. Specific gravity • Normal- 1.001- 1.040 • Normal ph: 4.5-8 • Usually slightly acidic between 6 & 6.5
- 24. Chemical characteristics and Urine R/E strip • Sugar • Ketones • Bile pigments • Bile Salts • Proteins • Blood • Serum elecrtrolytes
- 25. Microscopic examination • Crystals, Casts, cells/lpf • Epithelial cells,bacteria • Casts are cells wrapped in Tam-horsefall protein formed in renal convoluted tubules • WBCs casts---Kidney infection/pyelonephritis • RBCs Casts-- Glomerulonephritis
- 26. Casts in urine—Hyaline, WBCs, RBCs
- 27. Common Kidney disease TERMINOLOGY • VOLUME: 1-2.5 L/ day • Oliguria: < 400ml/day • Anuria< 100ml/day • Polyuria > 2.5 l/day
- 28. Minimumhistoryrequiredbeforeinterpretingbiopsy! Age; Onset: Rapid vs. insidious onset Duration Presenting complaints: Oliguria/anuria/ frothy urine/cola colored urine, edema, arthralgia/back pain, petechiae History: hypertension, diabetes, collagen vascular diseases (e.g. SLE, RA), congenital anomalies like deafness
- 29. Minimuminvestigationsbeforeinterpretingbiopsy! Urine routine: Gross/microscopic hematuria; dysmorphic RBCs +/-; RCBC casts +/-; Bland/active urinary sediments 24 hour urine protein / spot urine protein: creatinine ratio (spot PCR) Serum albumin Serum cholesterol Serum BUN, urea and creatinine (information about % rise in level compared to baseline is more informative than a single value) USG: size of kidney; cortico-medullary delineation Optional: Viral serology (HIV, HBV, HCV), ASLO titer, ANA / dsDNA/ ANCA, serum complement (C3, C4) level **UREA = BUN X 2.14
- 30. Definitionofsomeclinico-pathologicalterminologies • Significant proteinuria: > 150 mg per 24 hours • Sub-nephrotic proteinuria: < 3 g/ 24 hr • Nephrotic range proteinuria: > 3 to 3.5 g/ 24 hr or > 40 mg/m2/hr or spot urine PCR >2 • Nephrotic syndrome: Nephrotic range proteinuria + hypoalbuminemia (<2.5 g/ dL) + edema + hyperlipidemia (serum cholesterol >200 mg/dL) & lipiduria • Nephritic syndrome: Hematuria (dysmorphic RBCs/RBC casts/active sediments) + sub-nephrotic proteinuria (<3 g/dL) + Oliguria (<500 ml/24 hr) + hypertension + azotemia (rising BUN/urea/creatinine) • Rapidly progressive renal failure (RFRF): Rapid deterioration of renal function within 2 week to 3 months but normal sized kidney on USG (not synonymous with ARF)
- 31. Kidneybiopsy • Light microscopy (H&E, PAS, Silver, MTS optional – congo red) • Direct immunofluorescence (IgG, IgA, IgM, C3, C1q, kappa, & lambda) • Electron microscopy
- 32. • THANK YOU