First test examination of crystals Flashcards
nephrolithiasis
kidney stone disease
stones that are in the ureter
ureterolithiasis
urinary bladder stones which form or have
passed into the bladder
cystolithiasis
crystals can form before or after micturation
micturation=urination
Crystal precipitation after micturition is most commonly due
to:
- changes in urinary temperature, as can occur if the
urine is stored at room temperature or in
a refrigerator; - changes in urinary pH, as can occur in the
presence of contamination of urea-splitting
organisms.
abnormal crystals are usually seen in ___ urine
acidic
Prerequisites for identification of crystals:
– pH of urine
– morphology of crystals
– crystals solubility
– crystals polarization
abnormal acidic crystals
metabolic origin
abnormal alkaline crystals
Iatrogenic orgin
In vitro factors of urinary crystal formation
-Temperature (solubility decreases with temperature) - Evaporation (increases solute concentration) - Urine pH (changes with standing and bacterial overgrowth)
In vivo (body) factors:
Solute concentration - Kidney filtration rate - Urine pH - Diet - Excretion of diagnostic imaging and therapeutic agents
most crystals are clinically
insignificant
Generally, clinically significant crystals are present in
freshly voided urine, or in cases of ______
metabolic disorders
e.g. gout
- Metabolic disorders may produce crystals (4)
- Cystine (inherited metabolic disease)
- Leucine
- Tyrosine
- Cholesterol
- Iatrogenic disorders-high doses of some drugs and supplements may cause formation of crystals:
- Salicilates (Aspirin)
- Sulfonamides
- Ascorbic Acid (vitamin C)
_____ light is used for the identification of crystals
and other anisotropic substances.
Polarized
The first lens is referred to as the “_____ filter” and it
is nearest the light source, below the condenser
polarizing
The second filtering lens is called the “______” and is
located between the objective and the eyepiece lenses
analyzer
It is used for differential diagnosis between various
crystals
Birefringence
•Birefringence is a double refraction (or bending) of the
light into ___ rays, one is ____to the light axis
and other is at angles to it
two, parallel, right
Birefringence demonstrates crystal’s ability to split ____
into the spectrum
light
when examining with a polarizing filter and RED
compensator filter, the crystals are YELLOW
when aligned parallel to the slow axis of
the red compensator
but they turn BLUE when aligned across the
direction of polarization
Negative birefringence: (Y-B)
hen examining with a polarizing filter and red
compensator filter, the crystals are BLUE
when aligned parallel to the slow axis of
the red compensator
but they turn YELLOW when aligned across the
direction of polarization
• Positive birefringence
ACIDIC URINE CRYSTALS
Uric acid
• Calcium Oxalates
• Amorphous Urates
Are usually formed when urine pH
uric acid crystals
can look like barrels, rosettes, rhomboids, needles
or hexagonal plates. usually amber in color, irrespective of the size
or shape of the individual crystal.
uric acid crystals
Uric acid crystals are only pathogenic when in…
freshly voided urine.
______ are much more common in
patients with urate urolithiasis or acute urate
nephropathy.
Urate crystals
A high uric acid level in the urine may be due to:
gout
- high-purine diet
- Lesch-Nyhan syndrome (when the body is not able to
process purine due to lack an enzyme)
- cancer metastases
- rhabdomyolysis (due to breakdown of muscle fibers)
- myeloproliferative disorders (e.g. multiple myeloma,
leukemias)
Low uric acid levels in the urine may be due to:
- inability of kidney to get rid of uric acid well, which can lead to gout with kidney damage - chronic glomerulonephritis - lead poisoning - long-term (chronic) alcohol use
May exhibit characteristic “lemon or football” shape appearing singly or in clusters, May also form into barrels, needles, rhomboids, and other shapes
Uric acid
Dissolves in alkali • Insoluble in – alcohol – HCl – acetic acid
Uric Acid
will re-solubilize when heated at 60° C
Amorphous urates
often seen in:
- acidic urine,
- especially after refrigeration
Amorphous Urates
formed in urine pH 6.8 - 7, Colorless or yellowish, Needles or slender prisms occurring in
sheaves or clusters.
sodium urates
- are formed usually in acidic urine (pH 6)
- may also been seen in neutral urine
- they may occur as either:
• Calcium oxalate crystals:
many small ones can be confused as amorphous
Calcium oxalate crystals
patients with urolithiasis (___ of all urinary tract stones
consists of oxalates or combination with calcium
phosphate)
75%
patients with acute renal failure due to ethylene glycol
(antifreeze) intoxication (______ calcium oxalate
crystals are found)
monohydrate
Dissolves in:
– NaOH
– HCl
calcium oxalate
Insoluble in:
– acetic acid
calcium oxalate
Crystals Commonly
Found in Alkaline Urine
Triple Phosphates
Calcium Carbonates Ammonium biurate
10-15% urinary calculi
Triple Phosphate crystals ( a.k.a. magnesium ammonium
phosphate, struvites)
frequently seen in patients
with urinary tract infections, triple stones
Triple Phosphate crystals ( a.k.a. magnesium ammonium
phosphate, struvites)
Exhibit distinct prism shape often termed “coffin-lid”
triple phosphate
Polarizes light
• Demonstrates birefringence (not all)
• Dissolves in
– Acetic acid
Triple Phosphate (cont.)
Calcium carbonate crystals are _____ found in urine, in
alkalinic pH
normally
A unique feature of _____ _____ is that the
crystals bubbling with hydrochloric acid or acetic acid. This
can help to confirm the presence of calcium carbonate in
the urine.
calcium carbonate
Found in alkaline urine pH 9
• Common seen in old specimens
• Abnormal only if found in freshly voided urine
Ammonium Biurate
Dissolves in
Acetic acid
– NaOH
– And when heated (60oC)
Abnormal Crystals of Metabolic Origin
- Cystine
- Tyrosine
- Leucine
- Cholesterol
