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الفرق بين Amorphous urates و Amorphous phosphates
Amorphous urates
The amorphous urates seen in urine specimens and are, most of the time, the result of refrigeration. A pink pellet after centrifugation is characteristic of amorphous urates. Under the microscope, amorphous urates appear as yellow-brown mass of small rounded particles.
These crystals often adhere to mucus threads and casts. This property sometimes generates structures that mimic the dirty brown cast. Polarized light examination can easily discriminate these urates pseudocasts.
Amorphous urates are of little clinical value.
Amorphous phosphates
Amorphous phosphates is the name given to a granular precipitate containing calcium and phosphate in an alkaline urine. Calcium phosphate crystals, regrouped under the term apatite, have mineralogical names that differ according to their chemical composition. The CaH2PO4*(2H2O) is called Brushite, the calcium hydroxyl phosphate is called hydroxyl-apatite, the calcium bicarbonate phosphate is called Dahlite or carbonate-apatite.
The main cause of this crystalluria is the alkaline pH that decreases the solubility of the calcium phosphate and entails a precipitation of the former. The alkaline pH can be caused by the diet (vegetarian, rich in phosphates..) but can also represent a pathological situation. Usually, the presence of these crystals is non significant. The distinction between amorphous urates and amorphous phosphates is often made on the urinary pH basis. With a simple examination of the centrifuge pellet, the precipitate of calcium phosphate is white, while that amorphous urate is pink.
The amorphous urates seen in urine specimens and are, most of the time, the result of refrigeration. A pink pellet after centrifugation is characteristic of amorphous urates. Under the microscope, amorphous urates appear as yellow-brown mass of small rounded particles.
These crystals often adhere to mucus threads and casts. This property sometimes generates structures that mimic the dirty brown cast. Polarized light examination can easily discriminate these urates pseudocasts.
Amorphous urates are of little clinical value.
Amorphous phosphates
Amorphous phosphates is the name given to a granular precipitate containing calcium and phosphate in an alkaline urine. Calcium phosphate crystals, regrouped under the term apatite, have mineralogical names that differ according to their chemical composition. The CaH2PO4*(2H2O) is called Brushite, the calcium hydroxyl phosphate is called hydroxyl-apatite, the calcium bicarbonate phosphate is called Dahlite or carbonate-apatite.
The main cause of this crystalluria is the alkaline pH that decreases the solubility of the calcium phosphate and entails a precipitation of the former. The alkaline pH can be caused by the diet (vegetarian, rich in phosphates..) but can also represent a pathological situation. Usually, the presence of these crystals is non significant. The distinction between amorphous urates and amorphous phosphates is often made on the urinary pH basis. With a simple examination of the centrifuge pellet, the precipitate of calcium phosphate is white, while that amorphous urate is pink.
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