Urinary crystals and renal calculi

what 4 factors contribute to crystal formation

solute concentration

pH

urine flow

temp

what are 6 normal crystals

amorphous

ca oxalate

uric acids

triple phosphate

ca phosphate

ammonium biurate

ca carbonate

what 3 conditions have clinical significant crystals

metabolic disease

renal disease

ingested substances

small yellow brown granules found when pH is 5.5-7

"brick dust"

dissolve at alkaline pH or temp >60C

amorphous urates

which form of amorphous urate crystals form at above and below 5.57 (pKa)

above 5.57- urate

blow 5.57- uric acid

which form of amorphous phosphate form at below 7.21 and above 7.21

below 7.21- dihydrogen phosphate

above 7.21- hydrogen phosphate

soluble at acidic pH

does not dissolve at 60C

white or gray in color

amorphous phosphates

can form at any pH

dihydrate form is envelope shape

monohydrate dumbbell shape mistaken for RBCs

about 50% derived from ascorbic acid

calcium oxalate

what foods are high in ascorbic acid

tea, coffee, chocolate

spinach, tomatoes, asparagus

small yellow brown balls found in neutral to slightly acidic urine

acid urates

colorless to light yellow slender prisms singly or in small clusters

monosodium urate

yellow to brown found in many shapes (diamond most common), barrel shape, rosettes, rhomboids

uric acid

3-6 sided prism form in alkaline urine

triple phosphate

dibasic= thin wedge like prisms or long needles

monobasic= irregular granular sheets

calcium phosphate

elongated rectangles or rhomboids, form in neutral or alkaline urine

magnesium phosphate

small colorless granular crystals found in alkaline urine

calcium carbonate

yellow brown spheres with spicules

form in neutral or alkaline urine

seen most frequently in urine after prolonged storage

ammonium biurate

what are 5 abnormal crystals

cystine

tyrosine

leucine

bilirubin

cholesterol

colorless hexagonal plates

found in <8.3 pH

dissolve at <2 pH

deposit in tubules

cystine

when are cystine crystals clinically significant

congenital cystinosis

cystinuria

fine needles colorless or yellow

found in acidic urine

overflow aminoaciduria

tyrosine

yellow to brown spheres having concentric or radial striations

found in acidic urine

overflow aminoaciduria

leucine

small clusters of fine yellow brown needles

found in acidic urine after excretion

bilirubin

clear flat rectangular plate

found in acidic urine

cholesterol

what are Iatrogenic crystals

formed from medications and their metabolites

found in talcum powder from gloves

dimple in middle

matlese cross formation in polarized light

starch

solid aggregates of chemical salts

renal calculi

what factors promote renal calculi

increased solute concentration

unchanging pH

urine stasis

presence of foreign body seed (bacteria, blood, EC)

three ways to treat renal calculi

lithotripsy

cytoscopy

surgery

how to prevent renal calculi

increase fluid intake

alter diet (reduce dairy)

impose alternate pathway

control pH by IV