to degenerative changes in the tubular epithelium. Cellular casts - are hyaline or granular casts with t

or immunoglobulin incorporated in their matrix. They are found in same conditions as excess hyaline casts. (ii) Densely granular -are found in all forms of glomerulonephritis, diabetic nephropathy, and in large numbers in amyloid disease, and malignant phase of essential hypertension. Waxy - Advanced stages of glomerulonephritis and renal amyloid disease. Fatty - Fat droplets embedded in hyaline casts in nephrotic syndrome Granular, epithelial, fatty and lipoidal casts all point to degenerative changes in the tubular epithelium. Cellular casts - are hyaline or granular casts with tubular epithelial cells on their surface. Those with only an occasional cell are common in many forms of renal disease; casts thickly covered with tubular cells are characteristic of acute tubular necrosis and the rapidly progressive and acute types of glomerulonephritis. White cell casts in acute pyelonephritis 'Renal failure casts' - Broad and large casts probably originating in distal tubules. Renal tubular epithelial cells - A sharp rise in these cells may be produced by certain drugs. Their number is greatly increased in acute tubular necrosis Malignant cells - may be visible as syncitia with prominent nuclei in stained filter preparations. "Telescoped urinary sediment" - Presence of more than 2 types of casts in a single urinary specimen together with leucocytes and erythrocytes usually implies lupus nephritis IV BACTERIOLOGICAL EXAMINATION - Bacteria - most commonly found are E. Coli, Pseudomonas pyocyaneus, Staphylococcus aureus, Proteus vulgaris, Klebsiella pneumoniae and Streptococcus faecalis. A clear relationship has been demonstrated between in vitro sensitivity of the organism and the outcome of treatment, and laboratory control of chemotherapy improves the chances of successful treatment. Spirochetes - Leptospira icterohemorrhagica Ova and parasites - Trichomonas vaginalis and ova of oxyuris vermicularis and of schistosoma hematobium Larvae of filaria Scolices and booklets of hydatid cysts Spermatozoa - sometimes found following nocturnal emissions, convulsions or prostatic massage. V. SPECIAL TESTS -Pregnancy test - Concentration of human chorionic gonadotrophin (HCG) increased (1-5 IU/ml) within one week after the first missed period Urinary free cortisol, catecholamines, etc - See Chapter 5. Assessment of Renal Function Indications -1. Renal disease - (a) Detection (b) Evaluating its severity. (c) Following its progress. 2. Evaluation of safety and effectiveness of drugs excreted by the kidneys TESTS AND INTERPRETATION OF RESULTS - I. Urine examination and usually a quantitative measurement of proteinuria II Glomerular filtration rate (GFR) is the most widely used test of renal function CALCULATION OF CLEARANCE GRF is assessed by estimating the clearance of a substance excreted by glomerular filtration The most commonly performed tests are - 1 Measurement of plasma concentrations of creatinine and urea which indirectly reflect GFR 2 Creatinine clearance estimations, which are much less convenient. and performed at infrequent intervals to follow the long-term course of diseases potentially causing renal failure Formula: The rate at which a substance is filtered will be the same as the rate of appearance in urine, that is, UV mmol/minute, where U is the concentration in urine (mmol/ml) and V is urine flow rate (ml/minute) The clearance (volume/time) can then be calculated by determining the volume of plasma which contains UV/mmoI/minute of the sustance, that is where P(mmol/1) is the plasma concentration To summarize formula for clearance Clearance = GFR if the substance is freely filtered Since the rate of glomerular filtration depends broadly on the number of glomeruli (hence nephrons) present, the amount of renal damage and therefore the severity of renal failure can be assessed by measuring GFR Factors influencing GFK: Increase - (a) Pre-renal factors - dehydration, hypotension, severe cardiac failure (b) Renal damage. (c) Urinary tract obstruction. (d) Low-protein diet. (e) Drugs-ACE inhibitors, NSAIDS Increase. - (a) High protein diet/meal. (b) Early diabetes. (c) Pregnancy (d) Growth hormone. (e) Acromegaly. (f) Diurnal variation (increased in afternoon) Plasma creatinine and creatinine clearance Creatinine is the most useful endogenous metabolism for assessing glomerular function, and is virtually all excreted by the kidneys, mainly by process of glomerular filtration To measure creatinine clearance, patient's urine output is collected for 24 hrs Plasma creatinine concentration (Per mmol/1) and urine creatinine concentration (Ucr mmol/ 1) are measured and the duration of urine collection and volume collected are recorded Normal creatine clearance is about 120 ml/minute (varies with body size). Creatinine Clearance (ml/min) - Plasma creatinine concentration - Normal Per is 0 04-0 11 mmol/1. Factors influencing plasma creatintine concentration - Increase- (a) Reduced GFR. (b) Increased creatinine load (increased muscle mass). (c) Reduced tubular creatinine secretion due to drugs (e g trimethoprim, triamterene, amiloride, spironolactone, probenecid). (d) Hemoconcentration (e.g. diabetes insipidus). Decrease - (a) Increased GFR. (b) Reduced creatinine load. (reduced muscle mass, liver failure). (c) Hemodilution (eg antidiuretic hormone excess) Plasma urea concentration: Normal equal to or <>