Pathology – Dr. MorganHired Scribe: Peter Nguyen

Thursday March 8, 2001Scribes: G3 and Ra

Urinalysis II

The bolded items will be tested (the same items are bolded in the handout). Dr. Morgan will also throw in 1 or 2 questions that deal with interpretation of urinalysis. For example: specimen is indicated to be of “clean catch midstream” from a 45 yo female. Numerous squamous epithelia cells are seen. Is this most likely due to contamination, transitional cell CA, or blah blah blah. The answer is contamination. “I don’t expect you to memorize all the false positives and false negatives with the possible exception of ascorbic acid.”

MICROSCOPIC EXAMINATION

Cells that are quantified per high power field – The term ‘high power field’ does not designate a uniform magnification that every laboratory uses but rather each laboratory has its own magnification that they term as ‘high power field.’ Regardless of the exact magnification, urine must be examined under the same magnification every time so that the results will be consistent. Thus every laboratory has its own normals for each cell per high power field.

  • WBC; RBC; bacteria and fungi; casts; squamous, transitional (that line the bladder) and renal tubular epithelia

Significance of microscopic findings

  • Dysmorphic erythrocytes

Not something that is routinely looked for. Signifies that bleeding is of renal origin, very pale or misshapen

  • Eosinophils

Seen with hypersensitivity reactions to drugs including penicillin.

It is very difficult to tell from neutrophils in an unstained specimen. Thus, the lab must be asked to look specifically for eosinophils so that a special stain can be used.

  • Lymphocytes

Seen with chronic inflammation (but not seen in urine very often).

  • Renal tubular epithelia (RTE)

Increased with tubular necrosis where they slough off due to hypoxia

Oval fat bodies seen in tubular epithelia of patients with hyperlipidemia. These are seen as Maltese crosses under polarized light:

Contain hemosiderin pigment with either hemoglobinuria (intravascular RBC lysis) or myoglobinuria (muscle damage). Slide of a Prussian Blue stain was shown.

  • Transitional epithelia (which line the bladder or the urethra)

May be increased with catheterization (cells are rubbed off) or transitional cell carcinoma.

  • Squamous epithelia

Presence in large numbers suggests vaginal or perineal contamination.

Slide of dysplastic squamous epithelia cells was shown. The lady whose specimen was shown turned out to have severe dysplasia and the perineal contamination caused the cells to turn up in the urinalysis.

  • Casts – can be of clinical significance

Hyaline casts

◦Translucent casts seen with proteinuria due to a renal problem or transient proteinuria.

◦Causes of transient proteinuria without true renal disease are exercise, fever, congestive heart failure and diuretic therapy.

◦Slide shown of a translucent cast with protein that is building up in the tubules.

Waxy casts

◦Broad refractile, blunt "broken-off" ends (like if a broken candle – one end is sharp)

◦Tubular obstruction and stasis as seen in chronic or end stage renal disease.

◦Basically a hyaline cast that has been there a long time (made up of a lot of protein)

Granular casts

◦Same significance as hyaline casts

◦Slide shown – looks like a hyaline cast but more granular. Must make sure that these are not actually cells (erythrocytes or leukocytes) because they are of different clinical significance – see below.

Erythrocyte casts

◦Diagnostic of intrinsic renal disease

Leukocyte casts

  • Seen with pyelonephritis (may be mixed with bacteria) or with glomerulonephritis (RBC casts also present)

RTE casts

  • Diagnostic of intrinsic renal tubular disease

Fatty casts

  • Oval fat bodies appear as Maltese cross by polarized light
  • May be seen with nephrotic syndrome and fat embolism

CRYSTALS

“You’ll notice that I have ‘crystals’ highlighted here. Crystals can potentially have clinical significance. I don’t expect you to memorize all of these crystals and their clinical significance.”

Scribe note – Dr. Morgan drew little pictures of each crystal, of which I have copied here. Surprisingly, these little pictures actually do look like the real crystals

Acid urine – can have crystals with pathologic significance

  • Amorphous urates

◦No clinical significance

◦Slide – don’t really have a shape or form and are colorless

  • Uric acid

◦Seen with hyperuricemia and gout

◦Slide – “ice cubes that are leaning over” and “pretty” under polarized light

  • Sodium urate

◦The salt of uric acid and thus has the same clinical significance

◦Slide – “toothpicks,” pretty under polarized light

  • Calcium oxalate

◦Ethylene glycol poisoning, severe chronic renal disease, ingestion of foods high in oxalate or vitamin C such as tomatoes, asparagus “Have you ever gone to the bathroom about an hour after eating asparagus and said to yourself ‘wow, my urine smells just like asparagus’”, rhubarb and oranges

◦Slide – “envelopes”

  • Bilirubin

◦Hyperbilirubinemia

◦Slide – yellowish brown “spikey things”

  • Cysteine

◦Congenital cysteinosis or cystinuria (all amino acids have clinical significance

◦Slide

  • Tyrosine

◦Aminoacidemia or severe liver disease

◦Slide – “hairball,” very fine brownish crystal

  • Leucine

◦Aminoacidemia or severe liver disease

◦Slide – spherules, looks like turtle shells under polarized light

  • Cholesterol

◦Nephritic syndrome and chyluria

◦Slide – notched plates

  • Medications

◦Eliminate crystals of known pathogenic significance (i.e. these crystals don’t look like any of the ones above)

◦Slide – enormous

  • Radiographic contrast media

◦High specific gravity

Alkaline urine – none of these crystals have pathologic significance.

  • Amorphous phosphates
  • Triple phosphate
  • Calcium phosphate
  • Ammonium biurate
  • Calcium carbonate