This document summarizes key points about urine sediment examination for the diagnosis and management of kidney disease. It discusses the advantages and limitations of automated vs manual urine analysis. Manual urine microscopy allows better identification of findings indicative of conditions like acute interstitial nephritis (granular casts, WBCs), glomerulonephritis (dysmorphic RBCs, RBC casts), and nephrotic syndrome (lipiduria, lipid casts). The presence of various cells and casts provides clues to the underlying kidney injury or disease process.

1. Urine Sediment Examination in the Diagnosis and
Management of Kidney Disease: Core Curriculum 2019
COREY CAVANAUGH AND MARK A. PERAZELLA (AM J KIDNEY DIS. (2018))
PRESENTER –SCIENTHIA SANJEEVANI
MODERATOR –DR KHULLAR
JOURNAL CLUB (13/3/19)

2. INTRODUCTION
 NON INVASIVE LIQUID BIOPSY
 CAN BE USEFUL AS WELL AS MISLEADING DEPENDING ON THE EXPERTISE OF
NEPHROLOGIST PERFORMING THE TEST
 LIMITATIONS
 Bland despite the presence of various intrinsic kidney diseases such as AIN,
proliferative lupus glomerulonephritis, ATN
 Presence of uric acid, calcium oxalate, and drug related crystals in urine of
asymptomatic patients.

3. AUTOMATED URINALYSIS
 ECONOMIC ADVANTAGES
 COMMONLY USED DEVICES
 IRIS Iq200-uses laminar flow technology which the digital imaging software identifies
cells and particles in uncentrifuged urine. Hundreds of images are captured using a
digital camera and characterized based on shape, contrast, and texture of the particle
 Sysmex UF-1000i
 Cobas u701-uses cuvettes and centrifuges the sample, and in 30 seconds, then
captures 15 images and classifies them into various categories, including hyaline casts,
pathologic casts, crystals, and nonsquamous epithelial cells.
 SediMax

4. In comparison to manual analysis……
 iQ200 automated system vs manual microscopy
 insensitive to ATN (recognise 24 % granular casts as comp. to 72 %- total n=25 )
 Study consisting 26 patients significantly greater no. of RTECs, granular casts, and dysmorphic
RBCs were seen by the nephrologist’s use of manual urine microscopy.
 Even after blinding to the clinical history, the nephrologist performing urine microscopy made the
correct diagnosis >90% of the time as compared to only 19% when a second nephrologist used
the automated urinalysis and laboratory-based microscopy report
 Two Cobas 6500 and Iris IQ200 systems
 Automated systems showed good correlation for erythrocytes (r = 0.87; P = 0.001) and leukocytes
(r = 0.92; P = 0.001)
 no correlation for pathologic nonepithelial cells (r = 0.16; P = 0.049) and very poor correlation for
crystals (r = 0.46; P = 0.001).
 inadequate to identify and classify sediment particles such as casts and crystals in highly
pathologic samples

5.  Cobas 6500 system and UX-2000 analyser compared with manual microscopy in
258 urine specimens sensitivity and specificity for pathologic casts
 39.2% and 98.1%, respectively, for the Cobas 6500 system
 45.1% and 93.7%, respectively, for the UX-200 system.
CONCLUSION
 Advantages -Time saving, standardized, and cost-effective
 not reliable to diagnose various kidney diseases such as ATN,
vasculitis, or crystalline-related kidney disease.

6. Manual Urine Microscopy
 collect spontaneously voided sample when possible, whereas urine collection in
patients with indwelling bladder catheters should be from the tube
 analyse a fresh urine sample within 2 hours of collection or quickly refrigerate to
allow viewing over the next 8 hours to avoid cell and cast degradation
 Before centrifugation
 inspect for color, clarity, and turbidity before centrifugation.
 Abnormal urine colors -potential endogenous (pigmenturia, lipids, etc) or
exogenous (drugs, foods, etc) processes

7. Color

8. Method
10 ml urine
check for pH and osmolarity by dispstick
Centrifuged for 5 min for atleast1500 rpm
Remove 9.5 ml of supernatent by suction
gentle manual agitation of the test tubes or gentle suction and expulsion of the
sediment by pipette is performed
single drop of urine sediment is placed on a standardized glass slide and
cover slipped.

9. pH
 pH can range from 4.5 -8.0
 Double indicator system- Methyl red (H + interacts at high concentration) and bromthymol blue are
used to give distinct color changes from orange to green to blue
 High Urinary pH (Alkali Urine) pH tends to be more alkaline after a meal (alkaline tide)
 Vegetarian diet, low carbohydrate diet or ingestion of citrus fruit
 Systemic alkalosis (metabolic or respiratory)
 Renal tubular acidosis (RTA I (distal)), Fanconi syndrome
 Urinary tract infections (Bacteruria with urea splitting organisms
 Drugs: Amphotercin B, carbonic anhydrase inhibitors (acetazolomide), NaHCO3, salicylate OD
 Stale ammoniacal sample (left standing)
 Low Urinary pH (Acidic urine)- First morning specimen is usually slightly acidic (5.0-6.0)
 High protein diet or fruits such as cranberries
 Systemic acidosis (metabolic or respiratory)
 Diabetes mellitus, starvation, diarrhoea, malabsorption
 Phenylketonuria, alkaptonuria, renal tuberculosis

10.  The sediment field is examined at low (original magnification ×10) and high power
(original magnification ×40) using brightfield or phase contrast microscopy with a
minimum of 10 fields (20 fields optimal) observed under each power
 cast survival time is pH dependent and they may degrade more quickly with
alkaline pH.
 The cover slip edges tend to accumulate more casts and should be included as a
part of the sediment field examination.

11. RBC
small and anucleate and may be isomorphic or
dysmorphic

12. LEUCOCYTE
 characteristic cytoplasmic granules and nucleus; about double the size of a RBC
 Glitter cells- in hypotonic urine, WBCs swell and granules exhibit Brownian
Movement
 Normal- 0-8/HPF

13.  neutrophils are the most common WBC in urine (urinary infection) but can also be
seen with inflammatory kidney lesions.
 about 10 to 15µm in diameter ( appro 6µm ,larger than RBCs and smaller than
RTECs (15-30µm] and have a multilobed nucleus
 difficult to identify in dilute / concentrated urine, alkaline or delayed viewing

14. EPITHILIAL CELLS
Squamous Epithelial Cells
Thin, flagstone-shape with distinct
edges; small, condensed, centrally
located nucleus about the size of a
RBC
Transitional Epithelial Cell
Variable size, dense oval/round
nucleus and abundant cytoplasm
Renal Tubular Epithelial Cells
Round/oval; small, dense nucleus
that is usually eccentric, and
granular cytoplasm

15. Renal Tubular Epithelial Cells
 Rarely appear in the urine of normal, healthy individuals
 More are seen in newborns than in older children and adults
 Presence of increased amounts of RTEs indicates tubular injury
 Exposure to heavy metals
 Drug-induced toxicity
 Viral infections
 Pyelonephritis
 Malignancy

16. Casts
 cylindrical and can be acellular (hyaline, proteinaceous, or granular) or contain
various cell types reflective of the type of kidney injury (RBCs, WBCs, RTECs,
crystals, lipids, or micro-organisms
 composed of a backbone of uromodulin.
 begin to form in the loop of Henle and further develop in the distal tubular
lumens.

17. RTECs and Casts
 As a result of necroptosis from ischemic and/or toxic injury to
tubules
 A size comparison can be made to a neighboring erythrocyte,
which is typically half the diameter of an RTEC (6 μm)
 Close differential- deep uroepithelial cells (RTEC if renal
parenchymal elements such as RTEC casts or granular casts are
present or the patient has proteinuria and an increasing serum
creatinine level
 PRESENCE signify more severe AKI and likelihood of progression
to a higher AKIN stage, need for dialysis therapy, or death.

18. Granular casts
 fine, course, or mixed (hyaline-granular cast),
 generally reflect tubular injury.
 composed of degraded cell lysosomes (seen as
granules on electron microscopy) admixed with ultra
filtered serum proteins or particles from degenerated
RTECs admixed with uromodulin.
 ATN, AIN, thrombotic microangiopathy
 muddy brown casts When granular casts are dense
and brownish/burnt umber  severe ATN

19. Hyaline casts
 composed primarily of uromodulin
produced by loop of Henle cells and
 may be seen when the decline in renal
perfusion leads to sluggish urinary
flow—dehydration, excercise
Indicate tubular obstruction with prolonged stasis seen in
cases like
renal failure, kidney transplant rejection, and some acute
renal
diseases
Waxy casts

20. Urinary findings in kidney syndromes

21. Acute Interstitial Nephritis
 Biopsy-proven AIN occurs in approximately 10% to 15% of hospital-acquired AKI ,
Drug exposure, which accounts for >70% of AIN
Mostly only clue to AIN is an increase in serum creatinine level and abnormalities in
urine. Urinalysis may show low-grade proteinuria with positive blood and leukocyte
esterase in the setting of a negative urine culture result.
FINDINGS
WBC ‘s
 retrospective study of biopsy-proven AIN – leukocyte esterase was positive in >80% of
patients
 leukocyturia (average of approx. 70% with a range of 20%-80%).

22. Hematuria is also seen in aprox 50% of AIN cases
Eosinophiluria
 Over-rated inv
 recent study in mayo clinic did urine testing and found that both >1% and >5%
thresholds for positive results failed to differentiate etween ATN, proliferative
glomerulonephritis, diabetic nephropathy, and cast nephropathy
WBC casts
 not highly specific because other inflammatory kidney lesions (proliferative
glomerulonephritis and acute papillary necrosis) may have them

23. White blood cells (with negative urine culture) are seen in the urine of a patient with acute
interstitial nephritis.

24. To conclude…
 often contains RTECs, granular casts, andWBCs (with negative urine culture
results).
 reflects tubular injury/tubulitis from the inflammatory interstitial process.
 WBC casts are rare, but when present are highly suggestive of AIN in the
of acute/chronic pyelonephritis

25. Nephritic Sediment
Nephritic sediment –erythrocytes and RBC casts.
 Hallmarks of glomerular bleeding is dysmorphic RBCs, including acanthocytes, or
G1 cells.
 Dysmorphic RBCs making up >5% of total RBCs support glomerular bleeding
 Dysmorphic RBCs and acanthocytes fairly specific for glomerular injury but lack
sensitivity
 Isomorphic RBCs are often seen with glomerulonephritis.

26.  Proliferative glomerulonephritis (lupus, vasculitis, membranoproliferative
Glomerulonephritis) -sterile pyuria and/or WBC casts in patients with dysmorphic
RBCs and/or RBC casts
 monitoring urine for hematuria, dysmorphic RBCs, and RBC casts - useful for
surveillance of patients with known glomerular disease
 Nephrotic syndrome have relatively bland (acellular) urine sediment, have
lipiduria and lipid casts.

27. Erythrocytes and RBC Casts
 Improved identification of RBC morphology with brightfield microscopy achieved
with lowering the condenser lens.
 Can be isomorphic and dysmorphic (G1 or non G1 cells )
 Isomorphic RBCs are approx. 6 μm and appear as erythrocytes observed on a
peripheral-blood smear.
 can be seen
 Glomerular injury
 Extraglomerular (AIN and renal cell carcinoma)
 extrarenal processes (nephrolithiasis, urologic cancers, urinary tract infections,
excessive anticoagulation, etc).
 RBCs and RBC casts can also appear after vigorous exercise

28.  Dysmorphic RBCs -different shapes, with a ring shape and single or multiple blebs
or protrusions.
 Due to loss of membrane, these cells are typically smaller ( approx. 3 μm)

29. Isomorphic RBCs along with crenated RBC forms are observed in a pa>ent with high urine specific gravity.

30. Urine sediment of a patient with infection-related glomerulonephritis reveals (A) dysmorphic red blood cells (RBCs),
including acanthocytes and isomorphic RBCs, and (B) RBC cast.

31.  To differentiate between) G1cells and dysmorphic non-G1 cells or pseudo-G1
cells (echinocytes, stomatocytes, schistocytes, sickled cells, poikilocytes, etc)
- membranous blebs, a doughnut shape with target configuration, and fragmented
cell contours
 Ghost cell, which is an RBC with low hemoglobin content and has a low refractile
index- no specific meaning

32. erythrocyte casts
 erythrocyte casts are specific for glomerular injury
 insensitive test.
To conclude
 the presence of hematuria, low-grade proteinuria, and WBC casts may indicate
either glomerulonephritis or AIN KIDNEY BIOPSY

33. Nephrotic sediment
Lipiduria and Lipid casts
 Free lipid droplets, oval fat bodies, lipid casts, and cholesterol crystals
 Circular fat droplets containing cholesterol esters will produce birefringent
Maltese crosses under polarized light.
 Oval fat bodies are either macrophages or RTECs that are engorged with fat
droplets that these cells have endocytosed.
 Lipid or“fatty” cast- Free lipid droplets, cholesterol crystals, and/or oval fat
bodies can be embedded in a cast matrix

34. lipid casts is seen under phase contrast microscopy in a pa9ent with nephro9c syndrome. B) Polariza9on shows
strong birefringence with Maltese cross forms within the cast

35. Crystalluria
Select Endogenous Crystals
Calcium Oxalate
 Most common , not always
pathological
 Monohydrated: colorless ovoid, dumbbells,
rods, pH- 5.4-6.7, strong Birefringence
 Dihydrated: colorless bipyramidal,
envelopes, pH- 5.4-6.7, weak
Birefringence

36. Uric acid
 Amber with variety of shapes: rhomboids,barrels,
rosettes, needles, 6-sided plates
 pH 5.4-5.8
 Strong polychromatic
 Causes
 uric acid nephrolithiasis
 rhabdomyolysis
 lymphoproliferative disorders complicated by tumor
lysis syndrome
 Amorphous urates within urine may be found in
urine
 from healthy individuals

37. Calcium phosphate
 Prisms, sticks, needles, stars, rosettes in
isolation or in aggregates
 pH 6.7-7.0, strong Birefringence
 which appear more like uric acid crystals, but
are not birefringent
 pH 6.2-7.0, strong Birefringence
 Trapezoids, prisms, feather-like, “coffin lids”
 not seen in urine from healthy individuals and
typically occur in urine infected with urease-
producing microorganisms such as Ureaplasma
urealyticum and Corynebacterium urealyticum.
Triple phosphate

38. Cystine
 cystinuria.
 pH 5.5, Weak Birefringence

39. Tyrosine, Leucine and Cholesterol

40. Select Drug Crystals
Sulfonamides
 shocks or sheaves of wheat or shells with an
amber color and radial striations, strongly
birefringent
 Sulfadiazine most common sulfonamide
associated with crystalluria and crystalline
nephropathy
 Large intravenous doses (4-6 g/d of
sulfadiazine or 50-100 mg/kg/d of
sulfamethoxazole), volume depletion, acidic
urine, and underlying acute or chronic
kidney disease increase the risk for
crystalline nephropathy.

41. Atazanavir
 crystalluria, nephrolithiasis, crystalline nephropathy,
and acute and chronic interstitial nephritis.
 is maximally soluble at pH of 1.9, and risk for crystal
precipitation and calculi formation increases as pH
becomes more alkaline.
 Other risk factors- prolonged duration of therapy (2-3
years), ritonavir boosting, previous nephrolithiasis with
indinavir, and elevated bilirubin levels.
 are needle shaped and mildly birefringent
 calculi are radiolucent and typically beige to yellow
Ciprofloxacin
 typically colorless or brownish and are strongly
birefringent
 Large intravenous doses, older age, underlying
kidney disease, and alkaline urine increase risk for
crystal precipitation
 crystalline-induced AKI can occur with standard
doses and physiologic urine pH

42. Acyclovir
 prodrug valacyclovir a rare cause of crystalline
nephropathy
 rapidly excreted into urine by both tubular secretion
and glomerular filtration
 Risk factors for AKI - high doses (>1,500 mg/m2/d),
bolus intravenous administration, preexisting kidney
disease, and volume depletion.
 needle shaped,birefringent, and accompanied by
leukocytes, which may engulf the crystals.
 Prevention -reducing drug concentration in the
tubular lumen by establishing urinary output of 100
to 150 mL/h, avoiding rapid infusions, and large
doses.

43. Methotrexate
 Methotrexate and its metabolite 7-hydroxy-
methotrexate excreted predominantly in urine.
 limited solubility of drug and metabolites in acidic
urine, intratubular precipitation can lead to AKI from
crystalline nephropathy
 To prevent/reduce crystal precipitation and AKI-
Intravenous fluids and urinary alkalization
 compact or needle-shaped golden-brown crystals
arranged in annular structures, free or within casts
 The crystals are strongly birefringent.