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Urinalysis in The Clinical Practice Bassam Saeed MD. FRCP. DIS. DIU, Jahra Hospital - Kuwait The 2nd Int. Al-Jahra Pediatric Conference . May 5-7, 2017 Kuwait The Urinary Sediment Today Mostly performed in central laboratories – Far from bedside – Without the correct equipment and knowledge Too often neglected even by nephrologists A Correct Urine Collection Give the patient written and simple instructions Collect the first or the second urine of the morning Avoid strenuous physical effort Wash the external genitalia Uncircumcised male: uncover the glans Female: spread the labia of the vagina Collect mid-stream urine Avoid urine collection during menstruation Give the patient a proper urine container A Proper Microscope Phase Contrast & Polarized Light Why Phase Contrast …? The particles are much better seen against the background Why Polarized Light …? Polarized light is extremely useful to correctly recognize the crystals. Uric acid crystals assume a typical polychromatic appearance Why Polarized Light …? Polarized light is also important to correctly identify lipid particles Lipid particles appear as “Maltese crosses” which is, “shining” particles containing a “black cross” A Proper Report Particles of Nephrological Importance Cells Lipids Casts Crystals Microorganisms Erythrocytes A frequent finding Two main types: 1- Glomerular (Dysmorphic) 2- Non-glomerular (Isomorphic) Hematuria A simple method for identifying glomerular bleeding Urinary erythrocytes Glomerulonephritis Urological disorders Dysmorphic 55/58 0/30 Isomorphic 0/58 30/30 Mixed 3/58 0/30 Fairley, Birch, Kidney Int. 1982;21:105 Detection of Glomerular Bleeding by Phase Contrast Microscope > 80% cut-off for the definition of a hematuria as glomerular or non-glomerular Fassett RG. et al, Lancet 1982; I: 1432-34 Problems Associated With The Analysis of U-RC Morphology Requires experience Is exposed to the risk of low interobserver reproducibility Still lack of univocal criteria for defining hematuria as glomerular or non-glomerular Acanthocyturia: A subtype of dysmorphic erythrocyte A characteristic marker for glomerular bleeding Kohler H, Wandel E, Brunck B,. Kidney Int. 1991;40:115-20 What is the main indication for the evaluation of urinary erythrocyte morphology in clinical practice? Leukocytes [more often PMNs] Leukocyturia = Inflammation of whatever cause including immunological disorders such as glomerular diseases . Pyuria ● Present in practically all episodes of symptomatic UTI ● Lacking in more than 50% of covert bacteriuria ● Pyuria is not diagnostic of UTI ● Pyuria may be found in: 1- febrile children with infections outside UT. 2- Inflammatory diseases in or near to the UT. 3- Contamination from the vagina. Nitrite Test ● Ability of most U. pathogens to reduce nitrate to nitrite ● Requires a long bladder time (preferably > 4 h) ● The sensitivity is only 40-50% in infants (frequent voiding) In girls: ● The specificity is over 99% ● Practically equivalent to bacteriuria In boys: ● less reliable ● the nitrite accumulate under the prepuce false positive result Casts Formation Distal tubules and collecting ducts Matrix Tamm-Horsfall glycoprotein Different types Different clinical meanings Clinical Meaning of Casts Whatever particle is contained in a cast comes from the kidneys Leukocyte Casts: GN, Pyelonephritis .. Leukocyte Casts ● A rapid and inexpensive method ● A classical finding of renal infection ● Easily overlooked if massive pyuria ● Easily dissolved in alkaline urine ● Low sensitivity Epithelial Casts: ATN, GN .. Bacterial Casts Rare… Yeast Casts Candial cast Urinary Crystals “Common” crystals Pathological crystals Crystals due to drugs Uric Acid Crystals acidic urine Calcium Oxalate Monohydrated Calcium Oxalate Byhydrated Calcium Phosphate Crystals alkaline pH Triple Phosphate Crystals alkaline pH Clinical Importance of “Common” Crystals (I) In most instances, UA, Ca-Ox, and Ca-P crystals are due to: A transient super saturation of the urine which is caused by: Foods Dehydration Changes of urine pH Clinical Importance of “Common” Crystals However, Especially when they are persistent in the same patient they may be associated with: A METABOLIC DISORDERS such as: Hypercalcuria Hyperoxaluria Hyperuricosuria Pathological Crystals Cholesterol Cystine Leucine Tyrosine 2, 8 dihydroxy adenine Cholesterol Crystals Cysteine Crystals Cysteinuria (acidic urine) 2,8 Dihydroxy Adenine Crystals Factors Favoring Drug Crystalluria Drug overdose Dehydration Hypoalbuminemia Urine pH Amoxicillin precipitates at acidic urine Ciprofloxacine precipitates at alkaline urine The Urinary Sediment in Clinical Practice Persistent isolated microscopic hematuria: Glomerular or non-glomerular..? Glomerular diseases: Proliferative or not proliferative Flare up..? Acute tubular necrosis: With or without RBCs/RBC casts, myogloin casts, crystals..? Urinary tract infection: With or without WBC/Tubular Cells casts..? Persistent Isolated Microscopic Hematuria PIMH Persistent Isolated Microscopic Hematuria PIMH Conclusion: 1. Good agreement between U-RC morphology and renal biopsy findings 2. Acanthocytes (>5%) the best marker of glomerular hematuria 3. RBC casts a rare finding Dipstick Testing of The Urine Protein: /False positive result/ Concentrated urine Very alkaline urine Gross hematuria Pyuria Bacteriuria Antiseptics Detergents Drugs such as Phenazopyridine Excessive delay in reading Dipstick Testing of The Urine Protein: pitfalls Testing urine produced while recumbent (first morning sample) to exclude postural or orthostatic proteinuria. Vigorous exercise and fever may increase urinary protein Urine pH UpH Renal output of acid reflects acid load status UpH indicates U. free hydrogen ions (FHI) The renal capacity to excrete FHI is limited Thus, UpH is of limited value in the assessment of acidosis UpH must be done with a pH meter, rather than a dipstick which is far too inaccurate Glycosuria Improper urine container (cans, bottles)..? Check concomitant blood sugar 1- High blood sugar: IV fluids with dextrose DM 2- Normal blood sugar: Primary isolated glycosuria Fanconi’s syndrome Urine Osmolality Versus Specific Gravity The SG may be converted into Uosm by multiplying the last 2 figures of the SG by 40 Urine Osmolality Versus Specific Gravity No falsely low SG Well diluted urine Close correlation between Uosm and SG There is falsely high SG Larger molecules in urine (glucose and radiocontrast media) Altered correlation between Uosm and SG SG might falsely suggest concentrated urine Urinary Cytology Decoy Cells BK Virus Allograft Nephropathy Sensitivity 100% Why, then, such a valuable test Is so frequently neglected by us..?